# data[].attributes.attachment_link.readable_text
Abstract

The purpose of this study was to determine the effects of body mass-based squat training on body composition, muscular strength and motor fitness in adolescent boys. Ninety-four boys (13.7 ± 0.6 yrs, 1.60 ± 0.09 m, 50.2 ± 9.6 kg) participated in this study and were randomly assigned to training (n = 36) or control (n = 58) groups. The training group completed body mass-based squat exercise training (100 reps/day, 45 sessions) for 8 weeks. Body composition and muscle thickness at the thigh anterior were determined by a bioelectrical impedance analyzer and ultrasound apparatus, respectively. Maximal voluntary knee extension strength and sprint velocity were measured using static myometer and non-motorized treadmill, respectively. Jump height was calculated using flight time during jumping, which was measured by a matswitch system. The 8-wk body mass-based squat training significantly decreased percent body fat (4.2%) and significantly increased the lean body mass (2.7%), muscle thickness (3.2%) and strength of the knee extensors (16.0%), compared to control group. The vertical jump height was also significantly improved by 3.4% through the intervention. The current results indicate that body mass-based squat training for 8 weeks is a feasible and effective method for improving body composition and muscular strength of the knee extensors, and jump performance in adolescent boys.

An 8-wk body mass-based squat exercise training decreased percent body fat in adolescent boys.

The body mass-based squat exercise training increased muscle size and strength capability of the knee extensors in adolescent boys.

The squat exercise training improves vertical jump height in adolescent boys.

Key words: School-based training, force-generating capacity, motor fitness, adolescents.

Introduction

Resistance training with moderate- and high-loads is an effective method for improving body composition and muscular strength from childhood to adolescence (Behringer et al., 2010; Malina, 2006) and does not appear to adversely affect growth or cause any injuries when it is executed with proper technique (Malina, 2006). Prior studies (Faigenbaum et al., 2002; Lillegard et al., 1997; Lubans et al., 2010; Ozmun et al., 1994; Sailors and Berg, 1987; Velez et al., 2010; Weltman et al., 1986) have adopted supervised programs using training equipment which enables moderate to heavy resistance load. On the other hand, a body mass-based exercise such as a jump and squat can be performed without space or equipment concerns, and may not be too time demanding with large populations. Mackay and colleagues (Macdonald et al., 2008; MacKelvie et al., 2003; McKay et al., 2005; Naylor et al., 2006) have demonstrated that a 10- to 12-min body mass-based jump training improved bone mineral content, body composition and jump performances, and suggested that the body mass-based jump training increases physical activity opportunities throughout the school day (Naylor et al., 2006).

Recently, we demonstrated that a body mass-based squat training program improved knee extension strength in elderly individuals (Nakamoto et al., 2012; Yoshitake et al., 2011). The body mass-based exercise adopted in the prior studies has some advantages in that it can be performed anywhere and for a short duration (approximately 15 min) with large populations. However, there is less information concerning the influence of body mass-based training on not only muscle strength but also body composition and motor fitness in adolescents. If body mass-based training can be a modality for improving body composition, muscle strength and motor fitness for adolescents, it could be a safe and convenient training method for inclusion in school physical education programs. Therefore, the present study aimed to determine the effects of body mass-based training on body composition, muscular strength and motor fitness in adolescent boys.

Methods

Participants

Ninety-four boys (13.7 ± 0.6 yrs at baseline) participated in this study. All participants were recruited from our pilot school. The physical characteristics of the participants were similar to the normative data of Japanese boys reported by the Ministry of Education, Culture, Sports, Science and Technology. The participants were divided into training (n = 36) and control (n = 58) groups. The events of the extracurricular activities in training group, in which participation in the current program was accepted prior to intervention, consisted of table tennis (n = 12) and volleyball (n = 11), track and field (n = 5), and Japanese archery (n = 8). Those in control group were baseball (n = 24), soccer (n = 22), swimming (n = 5) and kendo (n = 3). The number of times participating in a week and duration involved in their athletic activities in a day were 5.0 ± 2.0 days/week and 2.4 ± 0.9 h/day respectively. All participants involved in the activities had experienced competitions at a regional level.

This study was approved by the ethical committee of National Institute of Fitness and Sports in Kanoya (No. 10-3) and was consistent with their requirements for human experimentation. Prior to the experiment, all participants and their parents were informed of the purpose and procedures of this study and possible risks of the measurements beforehand. Written informed consent was obtained from each subject and their parents/legal guardians.

Experimental design

A parallel control- intervention research design was used in this study. The training period was 8 weeks. The exercise used was a body mass-based squat movement at a pace of once every 2 s. We instructed the participants to squat until their thighs were parallel to floor. In a preliminary study using 16 young adults (9 males and 7 females), a training program with exercise style adopted here for 8 weeks (5-6 times/week) produced a significant gain in isometric maximal voluntary knee extension strength. In the training program, the participants were required to repeat the squat movement for 3 minutes at a pace of once every 2 s (<90 repetitions/session). By taking this result into account, we set the target number of repetitions per day for the squat movement of 100 repetitions/day and the participants were required to perform it after their school curriculum excluding holidays (4-6 days/week). The number of the performed training sessions was recorded in a notebook by the participants. The control group was asked to refrain from any resistance training and maintain their normal physical activities and nutrition behaviors throughout the intervention period.

Outcome measurements

The anthropometry, body composition, muscular strength, and motor fitness were determined before and after the intervention. The examiners performed outcome measurements as below, and were blinded to which groups (training group or control group) the participants belonged to.

Measurements of anthropometry and body composition: Body height was measured using a manual stadiometer to the nearest 0.1 cm. After cleaning their feet with a cloth soaked by alcohol, a bioelectrical impedance analyzer with leg-to- leg system (DC-320, Tanita, Japan) was used to determine body mass to the nearest 0.1 kg, and estimate percent body fat by using the input variables of body height and sex. The leg-to-leg system has a reliability for estimating body composition with 2.1% of coefficient of variation for inter-day measurement. (Nunez et al., 1997). Furthermore, this method has been adopted for determining the body composition for children (Sampei et al., 2008). Body mass index was calculated as mass (kg) divided by height squared (m ²). Lean body mass was calculated from percent body fat and body mass.

Measurements of muscle thickness at thigh anterior: Muscle thickness at the thigh anterior was measured by a B-mode ultrasound (Prosound 2, Aloka, Japan) with a linear scanner. During the measurement, the participants remained in a standing position with their arms and legs relaxed extended position. In accordance with a procedure described in an earlier study (Abe et al., 1994), the measurement site was precisely located and marked at the anterior surface in the middle of the femur length (the distance from the great trochanter of the femur to articular cleft between the femur and tibia condyles). A transducer with a 7.5 MHz scanning head was placed perpendicular to the underlying muscle and bone tissues. The scanning head was coated with water-soluble transmission gel, which provided acoustic contact without depressing the dermal surface. The obtained ultrasonographic images were printed out by an echo copier. The muscle thickness of thigh anterior was measured as the distance between the fat-muscle tissue and muscle-bone interfaces. According to dimensional analysis (Asmussen and Heeb0Oll-Nielsen, 1955), muscle thickness was divided by the one- third power of lean body mass. The precision and linearity of the image reconstruction have been confirmed elsewhere (Kawakami et al., 1993). The one examiner performed the muscle thickness measurements throughout this study. In preliminary experiments, the examiner performed the repeatability test of the muscle thickness measurements on 3 separate day (> 7 days) with 3 participants. The intraclass correlation coefficient for the muscle thickness measurement was > 0.97, satisfied the standard value of repeatability, > 0.75 (Vincent, 1995). Measurement error was less than 1.0 mm. The coefficient of variation for the test-retest of the muscle thickness values was less than 5%.

Measurements of maximal knee extension strength (KES): Maximal voluntary strength in knee extension was measured using a specially designed myometer (TAKEI, Niigata, Japan) in accordance with a procedure described in previous studies (Nakamoto et al., 2012; Yoshitake et al., 2011). The right leg was measured for all participants. The participants sat on the machine at 90 degree of hip and knee joint. The subject's hip was fixed by a non-elastic belt to prevent their hip from moving. The participants gradually exerted muscle force from rest to maximum in 3 to 4 seconds and then sustained at maximum for approximately 2 s. Participants performed at least two trials with a 2-min rest between trials. If the difference in the measured score of the two trials was >10%, an additional trial was performed. The highest value for the trials was used for analysis. The KES was divided by body mass2/3 (KES/BM).

Measurement of sprint velocity: As described in the previous studies (Funato et al., 2001; Yanagiya et al., 2003), the sprint velocity was measured by a non-motorized treadmill to avoid the influence of the difference in measurement environment on sprint performance. The treadmill was specially designed (D-08011d, Takeikiki, Niigata, Japan) and consisted of a low friction belt, a small flywheel, a handlebar and a rotary encoder. The participants gripped a handlebar in front of them keeping both arms straight and in a horizontal position during running. The height of the handlebar was adjusted to the position of the horizontally straightened arms when each subject ran on the belt. The participants were required to start with standing position at rest and then to accelerate the belt as quickly as possible up to the highest velocity of the belt which was maintained for a few seconds. Participants performed at least 2 trials with 2-min rest between trials.

Electrical signals from the encoder were amplified and fed into a personal computer via an A/D converter (ADA16-8/2(CB)L, CONTEC, Japan) at a rate of 100 Hz. The pulses produced by the pulse generator were converted to the displacement of the belt by multiplying by a predetermined conversion factor. The instantaneous velocity of the belt was determined by differentiating the horizontal displacement of the belt. The sprint velocity was defined as the mean value of the six steps included maximal sprint velocity. The highest value between trials was used for analysis.

In a preliminary experiment, we confirmed whether the sprint velocity measured by the non-motorized treadmill is feasible as index of that on the ground. As the result, the internal consistency between the methods for sprint velocity was 0.87, indicating that the reliability of the two assessments is acceptable (> 0.70) (Bland and Altman, 1997).

Measurement of jump height: The participants were in a standing position, and performed a counter movement jump as high as possible. The position of the jumper on the mat was the same for takeoff and in landing. When jumping, the participants kept their hands on their hips and jumped vertically on a matswitch platform. The height of vertical jump was calculated from the following equation. (Bosco et al., 1983).

where g is acceleration due to gravity (9.81 m/s ²) and t is the time of the flight of the jump (s). The t taken from takeoff to ground contact was measured by a matswitch system (Multi Jump Tester, DKH, Japan).

The participants completed 3 trials with a rest interval of 1 min between the trials. The highest value for the three trials was used for analysis.

Assessment of sexual maturation

Prior to the intervention, the self-assessment of stage of pubic hair based on the criteria of Tanner (Tanner, 1962) was assessed for all participants. The stage consists of 5 classes. This method has been shown to have good validity for the assessment of secondary sex characteristics for Asian children (Duke et al., 1980). To reduce embarrassment, each participant went into a room by himself to complete the self-assessment anonymously (Gurd and Klentrou, 2003). Once completed, the self assessment was placed in a closed box. Eighty six of 94 boys (92%) completed the self-assessment.

Statistical analysis

Descriptive data are presented as means ± SDs. The normality of the independent variables was tested by Kolmogorov-Smirnov test, indicating that all variables were confirmed normal distributions by the test. Group differences at baseline were tested using an unpaired t-test. A paired t-test was used to test the significance of changes in all independent variables for both groups. We used an unpaired t-test to test the significance of the difference between the two groups in the relative changes in all variables. Statistical significance was set at p < 0.05. All data analyses were conducted using a statistical software package (SPSS 19.0 for windows, IBM, Japan).

Results

At baseline, no significant difference was found in each of the independent variables between the training and control groups. There was no significant difference in maturity status between the training and control groups (3.5 ± 1.4 vs. 3.6 ± 1.2). In the training group, training frequency and volume per day were 4.4 ± 0.8 days/week and 99.6 ± 1.3 repetitions/day.

Descriptive data on anthropometry and body composition in both groups are summarized in . After the intervention period, body height and mass significantly increased in both groups without significant group differences in the relative changes. Lean body mass significantly increased in both groups (p < 0.01), and the relative change was higher in the training group than in the control group (2.7% vs. 2.0%, p = 0.026). Percent body fat for the training group significantly decreased (p < 0.01) by 4.2%, whereas that for the control group did not. Body mass index did not significantly change in both groups. Thigh circumference significantly increased in both groups (p < 0.01), and the relative change was higher in the training group than in the control group (1.6% vs. 0.7%, p = 0.008). Muscle thickness at thigh anterior and its relative to lean body mass 1/3 were significantly increased by 3.2% and 2.3% in the training group (p < 0.05), whereas not in the control group.

Table 1.

presents descriptive data on KES, sprint velocity and jump height in both groups. KES and KES/BM significantly increased in both groups (p < 0.01), but the relative changes were higher in the training group than in the control group (KES, 16% vs. 8%, p = 0.014; KES/BM, 15% vs. 7%, p < 0.01). Sprint velocity did not change in the training group, but it significantly increased in the control group. On the other hand, jump height significantly increased in the training group (p = 0.042), but not in the control group.

Table 2.

Discussion

The main findings of this study were that the 8-wk body mass-based squat exercise training in adolescent boys : 1) decreased percent body fat, 2) increased lean body mass, muscle thickness and strength of the knee extensors, and 3) improved vertical jump height. These results indicate that a body mass-based squat training for 8 weeks is a feasible and effective method for improving body composition, the strength capability of the knee extensors and jump performance in adolescent boys. As a practical application, the body mass-based squat exercise training (100 repetitions/day, <10 min/day) can be conducted easily with large populations in terms of no special equipment and facilities. The number of inactive and obese youth has increased markedly over last two decades (Ogden et al., 2010), and it has links with the occurrence of diabetes, heart disease and hypertension (James, 2004). Individuals who develop a routine of participating in physical activities that can be easily carried into adulthood may be more likely to become active adults (Corbin, 2002). Taken together, these findings suggest that the body mass-based squat training is feasible training method for adolescents, which could be easily added in to school-based physical education programs for adolescent boys.

The changes in body height and mass in the training group were similar to those in the control group. This is consistent with the finding of Malina, 2006 in which similar changes in body size were found, regardless of participation in training. In addition, the observed gains in body height and mass are comparable to those in the earlier studies which have examined the effect of resistance training in adolescents (body height, 0.7-2.2 cm; body mass, 0.6-1.1 kg) (Lubans et al., 2010; Vrijens, 1978). The training group showed a significant decrease in percent body fat, indicating that the body mass-based squat exercise training can improve body composition. The observed changes in percent body fat are similar to those reported in supervised resistance training with free weight, machine and elastic tube (Lubans et al., 2010; Velez et al., 2010).

At baseline, the thigh girth and muscle thickness at the thigh anterior were comparable to the findings of Kanehisa et al., 2003. These variables were increased by the current training and the training-induced gains were greater in the training group than in the control group. These results are consistent with the findings of Vrijens, 1978 in that the girth and muscle cross-sectional area of thigh were increased by high intensive resistance training.

The training group showed a significant improvment in muscle strength. The gains in knee extension strength (16%) and its relative to body mass (15%) were relatively lower than those observed in prior studies with supervised modality using free weight and machine (19-35%) (Faigenbaum et al., 1999; 2002; 2007a; Lubans et al., 2010; Sailors and Berg, 1987), whereas comparable for those with body mass-based exercise training for elderly individuals (9-22%) (Aniansson and Gustafsson, 1981; Kubo et al., 2003; Nakamoto et al., 2012; Yoshitake et al., 2011). For the knee extensors in young and elderly individuals, muscular activity level during body mass-based squat exercise is associated with muscle strength per body mass (Fujita et al., 2011). Knee extension strength per body mass in adolescents increases across age (De Ste Croix et al., 2002). Taken together, it is reasonable to assume that muscular activity levels during the squat exercise are relatively higher in adolescent boys, and so it would appear to be a sufficient overload for improving knee extension strength. However, Behringer et al., 2010 pointed out that training-induced effects in adolescents are attributed to more training duration as well as frequency than training intensity. As the content of the training program used in this study, the duration was short (8 weeks), the frequency was higher (4.4 ± 0.8 days/week) compared to that used in the earlier studies (2-3 days/week) (Faigenbaum et al., 1999: 2002: 2007a; Lubans et al., 2010; Sailors and Berg, 1987). Hence, it seems that relatively high training frequency would be needed to improve muscular strength through body mass-based squat training.

The vertical jump height significantly improved through the intervention. Earlier findings regarding the effect of resistance training on motor fitness are very unclear (Faigenbaum et al., 2002; 2007a; 2007b; Lillegard et al., 1997; Weeks and Beck, 2012; Weltman et al., 1986). Weltman et al., 1986 demonstrated that resistance training including squat jump exercise increased vertical jump, but not standing long jump. Faigenbaum et al., 2007b showed that, in adolescent boys, a greater gain in sprint velocity was obtained in the combined training of plyometric and resistance exercises, as compared to only resistance training. Considering these findings, it seems that the improvement in jump performance may be affected by the specificity of the squat exercise which is performed due to force-production to vertical direction.

We should comment on some limitations of the present study. Firstly, the current data was analyzed, regardless of the events of the after-school activities in which the subjects participated. Hence, there is a possibility that the current findings might have been influenced by event-related differences in the after-school sports activities. However, the initial values in the measured variables for the training group did not significantly differ from the control group. Furthermore, regular participation in sport training during puberty and the adolescent spurt do not appear to influence on body size attained in boys (Malina and Bielicki, 1996; Malina et al., 1997). Considering these findings, it is likely that the effect of event-related difference in the training-induced change might be less for the current results. Secondly, the current findings were obtained from only adolescent boys. Weeks and Beck, 2012 have demonstrated that, for adolescents, the execution of body mass-based jump training in school produced sex- and maturity-related differences in the training-induced changes for lean body mass and jump performances. Unfortunately, we did not have the relevant data, and further investigations are needed to clarify this point.

Conclusion

In summary, the current results indicate that body mass-based squat training for 8 weeks is a feasible and effective method for improving body composition and muscular strength of the knee extensors, and jump performance in adolescent boys.

Acknowledgements

This work is supported by the Grant-in-Aid for Scientific Research (B) (22300218). The authors have no conflicts of interest to disclose.

Biographies

References

Abe T., Kondo M., Kawakami Y., Fukunaga T. (1994) Prediction equations for body composition of Japanese adults by B-mode ultrasound. American Journal of Human Biology 6(2), 161-170

Aniansson A., Gustafsson E. (1981) Physical training in elderly men with special reference to quadriceps muscle strength and morphology. Clinical Physiology 1(1), 87-98

Bland J.M., Altman D.G. (1997) Statistics notes: Cronbach's alpha. British Medical Journal 314, 572. [PMC free article]

Corbin C.B. (2002) Physical Activity for Everyone: What every physical educator should know about promoting lifelong physical activity. Journal of Teaching in Physical Education 21(2), 128-144

Faigenbaum A.D., McFarland J.E., Keiper F.B., Tevlin W., Ratamess N.A., Kang J., Hoffman J.R. (2007b) Effects of a short-term plyometric and resistance training program on fitness performance in boys age 12 to 15 years. Journal of Sports Science and Medicine 6, 519-525 [PMC free article]

McKay H.A., MacLean L., Petit M., MacKelvie-O'Brien K., Janssen P., Beck T., Khan K.M. (2005) "Bounce at the Bell": a novel program of short bouts of exercise improves proximal femur bone mass in early pubertal children. British Journal of Sports Medicine 39(8), 521-526 [PMC free article]

Tanner J.M. (1962) Growth at adolescence. 2nd edition Oxford: Blackwell Scientific Publications

Vincent W.J. (1995) Statistics in Kinesiology. Champaign IL: Human Kinetics

Vrijens J. (1978) Muscle strength development in the pre-and post-pubescent age. Medicine Sport 11, 152-158

# data[].attributes.attachment_link.title
Effects of Body Mass-Based Squat Training in Adolescent Boys

# data[].attributes.attachment_link.description
The purpose of this study was to determine the effects of body mass-based squat training on body composition, muscular strength and motor fitness in adolescent boys. Ninety-four boys (13.7 ± 0.6 yrs, 1.60 ± 0.09 m, 50.2 ± 9.6 kg) ...

# data[].attributes.headline
9) technical factors that limit performance in the back squat

# data[].attributes.subject
9) technical factors that limit performance in the back squat

# data[].attributes.attachment_link.readable_text
INTRODUCTION

Fundamental movement skills are essential for participation in physical activity and mitigating the risk of injury, which are both key elements of health throughout life.( 25) Young people, for example, without adequate motor skill proficiency in the early developmental years may experience a heightened risk of sports-related injuries during adolescence and into adulthood.( 11, 32, 34) Thus, development of competence in fundamental movements must be viewed as an essential component of preparatory training prior to vigorous physical activity and organized, competitive sport. Some fundamental movement patterns include running, throwing, lunging, and squatting,( 25) and these fundamental movements have direct biomechanical and neuromuscular implications to successful performance with dynamic tasks inherent to many popular sports and physical activities enjoyed by youth and young adults.( 24, 35) Movement competency as a principle extends through into the later adult years, for whom the joy of independent living rests on their ability to maintain strength and mobility to avoid injuries such as falling.( 44)

The squat movement pattern is required for essential activities of daily living such as sitting, lifting and most sporting activities. It is also a staple exercise in training regimens designed to enhance performance and to build injury resilience.( 30- 32) Despite variations on how squat technique is instructed and executed to address specific performance goals, nearly all squat variations comprise a standard, basic, and fundamental blueprint that underlies the biomechanical technique that will support progressive physical attribute improvements and decrease the risk of training induced injuries.( 3) In addition, the unloaded back squat (herein referred to as "back squat") has been proposed for use as a screening tool to identify biomechanical deficits that may hinder optimal movement patterns compromising performance and injury resilience.( 20) In particular, the back squat can be used to assess an individual for neuromuscular control, strength, stability, and mobility within the kinetic chain.( 1, 4, 10, 31, 39, 42)

The purpose of this commentary is to deconstruct the technical performance of the back squat and the related evidence, as both a foundation training exercise and dynamic screening tool. Specifically, we aim to describe common functional deficits during back squat performance known to increase injury risk during training and dynamic sport. Identified deficits and injury mechanisms will be formalized together with anatomical variations that influence squat kinematics and kinetics. In the follow-up manuscript, we aim to present detailed targeted training exercises and techniques to correct biomechanical deficits, (Part II) which is vital to improve the technical skill and competence of the back squat.( 22) Achieving this competency is the foundation for younger individuals to partake in training progressions that enhance performance and injury resilience, and for older adults to live independently and safely.( 25)

The Back Squat

The back squat is widely regarded as one of the most effective exercises used to enhance athletic performance as it necessitates the coordinated interaction of numerous muscle groups and strengthens the prime movers needed to support explosive athletic movements such as jumping, running, and lifting.( 7) Furthermore, back squat proficiency supports derivative squat movements that translate to many everyday tasks such as lifting and carrying heavy objects, which relates this exercise to improve quality of life.( 43) The squat has also become more commonly used in clinical settings to strengthen lower-body musculature (especially posterior chain strength and recruitment patterns) with little to no harm on connective tissue after joint-related injury.( 7, 43) Specifically, closed kinetic chain exercise is commonly used throughout the rehabilitation process to avoid excessive strain being placed on the anterior cruciate ligament (ACL), making the squat a favorable exercise for rehabilitation.( 7, 17, 37, 43). It is highly recommended that an individual is first able to demonstrate proficiency during body weight back squat performance before advancing to more intense variations and derivatives of squatting such as externally loaded squats and plyometric training.

The back squat exercise is most often prescribed with an individual starting in a standing position with the feet flat on the floor, the knees and hips in a neutral, extended anatomical position, and the spine in an upright position with preservation of its natural curves.( 7, 43, 45) The squat movement begins with the descent phase as the hips, knees, and ankles flex. A common instruction is to descend until the top of the thigh is at least parallel with ground and the hip joint is at least level with or slightly below the knee joint ().( 3, 43) Ascent is achieved primarily through triple extension of the hips, knees, and ankles, continuing until the subject has returned to the original extended, starting position.( 3) The posterior torso muscles, particularly the erector spinae, are recruited via isometric muscle action to support an upright posture throughout the entire squat movement. Furthermore, the posterior torso muscles are assisted by the anterior and lateral abdominal muscles to further stiffen the torso by creating tension for the abdominal wall.

Prior to the initiation of the descent phase, it is recommended for the athlete to inhale approximately 80 percent of maximal inhalation and hold their breath to increase intra-abdominal pressure to enhance stability of the vertebral column (i.e., Valsalva maneuver) (Note: This amount of air may change with the load magnitude). This technique prepares the spine, which is a flexible rod, to bear compressive load. The Valsalva maneuver also establishes "proximal stiffness" that enables more power development in the shoulders and hips, enhancing limb force output and velocity.

Identification of Biomechanical Deficits during the Back Squat

The basic squat movement is considered by many professionals to be a valuable primary physical training exercise since it is a single compound maneuver that is highly sensitive to highlight biomechanical deficits.( 12, 13, 33, 42) Deficits identified during the back squat that can impair performance can be categorized as either inefficient motor unit coordination or recruitment (neuromuscular), muscle weakness, strength asymmetry or joint instability (strength), and/or joint immobility or muscle tightness (mobility).( 43) It is important to identify the biomechanical and anatomical limitation(s) that most egregiously underlies aberrant movements in order to ameliorate identified deficit(s) through an appropriate and effective targeted corrective strategy (Part 2).( 12, 13, 33, 42) With the use of the proposed Back Squat Assessment (BSA) screening tool (), a practitioner may be able to more efficiently and objectively identify underlying deficit(s) responsible for functional limitations during back squat performance and to guide corrective targeted exercise progressions.

Table 1

The Back Squat Assessment

The authors of this commentary developed the proposed Back Squat Assessment (BSA) () screening tool to assist practitioners in systematically identifying specific functional deficits to guide targeted corrective intervention. The authors propose that observed movement impairments or deficits via guidance of the BSA suggests that an individual may have an elevated injury risk and sub-optimal physical performance.( 4) Moreover, the BSA is a versatile tool that provides an alternative means to expensive and sophisticated laboratory evaluation to identify biomechanical deficits.

Ten criteria to be scored are provided in the BSA, which are subcategorized into three comprehensive domains: Upper Body, Lower Body, and Movement Mechanics (). The three domains are integrated into the BSA to improve the systematic assessment of the back squat. It may be challenging to score all 10 criteria of the BSA at once during real-time observation. The categorization of similar criteria into three domains offers a practitioner a strategic guide to focus attention on scoring one domain at a time. The Upper Body domain emphasizes the stability and posture of the head, neck, and torso. The Lower Body domain assesses the joint positions of the hips, knees, and ankles during the squat. Lastly, the criteria in the Movement Mechanics domain assess the timing, coordination and recruitment patterns of the back squat. All 10 criteria from the three domains can be individually assessed for neuromuscular, strength, and mobility deficits as prompted on the BSA score sheet ().

To initiate the assessment, the athlete should be asked to perform 10 continuous back squat repetitions. The BSA will necessitate analysis from the anterior, posterior, and lateral perspectives and therefore it may be advantageous for practitioners to record video of the athlete performing the BSA from all three perspectives to facilitate a more accurate and thorough deficit screening.

The criteria are written in the affirmative and each should be critiqued and scored independently of each other. If a single criterion is not met to standard, an observed deficit should be marked. Next, the practitioner should indicate if they believe the deficiency is related to a neuromuscular, strength, or mobility limitation by circling the respective category to guide targeted exercise corrections (Part 2). If unsure, mark all categories that are suspect to improper technique. A perfect score of 0 indicates 10 flawless squat repetitions. A deficit should be marked if the individual fails to demonstrate the desired technique of a criterion to perfection during 2 or more repetitions. Additional space for comments is provided on the score sheet and may be useful for a practitioner make supplementary notes to guide their targeted corrective intervention. An athlete should be referred to a licensed healthcare professional if they indicate pain or discomfort during any phase of the squat assessment.

Standardized Assessment

Arm Position Instructions

A light weight cylindrical dowel (wooden, metal, or plastic; approximately 1 ¼″ × 36″ long) is recommended to be used to set-up the athlete in a desired upper torso position while controlling for arm position. Furthermore, the use of a dowel in the back squat position can serve to prepare an athlete for future back squat progressions that incorporates external resistance. In addition, the dowel aided position likely facilitates engagement of the scapular stabilizers essential to upper body performance in the back squat.

Athletes are to be instructed to grip the dowel with a pronated grip slightly greater than shoulder width apart and assume a back squat set-up with the dowel resting comfortably on their contracted upper back musculature. Specifically, the dowel should be positioned across the posterior deltoids just below C7 of the cervical spine. Forearms should be held parallel to the torso and wrists should be kept straight and not flexed throughout the movement (). The person should be taught to "bend the bar" (pull the bar into trapezius) as this facilitates the back extensors, shoulder retractors and latissimus - all of which stiffen the torso, adding to injury resilience and performance capabilities. If a dowel is not available, the athlete can be instructed to mimic holding a dowel with their hands open palmed under their ears while retracting their scapulae.

Stance Instructions

The athlete should be instructed to assume an initial stance position with heels approximately shoulder-width apart and toes pointing forward or slightly outward by no more than 10-degrees. Extreme stance widths and foot positions (tibial rotation) are not recommended when initially instructing the squat and may limit the utility of the BSA. Escamilla and colleagues assessed the kinematics and kinetics of the squat at three varying widths (a wide stance, shoulder width, and narrow stance).( 8) A wide stance may increase patellofemoral and tibiofemoral compressive forces in the knee joint by up to 15% during descent.( 7, 9, 43) On the other hand, an excessively narrow stance may increase forward knee translation and therefore heighten anterior shear forces.( 7, 43) Therefore, a moderate stance width is encouraged for this standardized assessment.

In regard to foot position, it is important for the knee to function in its intended role as a hinge joint. During goal-specific squat exercise, moderate variations of foot placement may be warranted; however, it is recommended that athletes do not exceed 30 degrees of internal ankle rotation or 80 degrees of external rotation to maximize stability and promote normal patella tracking.( 21, 43) Still, extreme tibial rotation in a closed chain movement may potentially lead to increased stress on the static knee structures and should be avoided for most squat variations.

Script for Instructing the Assessment

Once the athlete is properly set-up with the dowel and stance in the appropriate position, verbal instructions for the BSA can be delivered. The authors recommend utilizing the following standardized verbal script to promote inter-rater reliability for the BSA:

"Please stand upright with feet shoulder width apart. Squat down until the top of your thighs are at least parallel to the ground, and then return to the initial starting position. Perform 10 continuous repetitions at a consistent, moderate pace or until you are instructed to stop."

Domain 1: Upper Body

Domain 1 is focuses on the musculoskeletal components of the upper body that are responsible for maintaining postural control during the squat.

1. Head Position

As a precursor to sports performance training for youth, the neck should demonstrate adequate physiological ranges of motion of flexion, extension, rotation, and side bending in absence of pain or discomfort. Simple neck rolls and head tilts can be used as an assessment for neck mobility. If an athlete indicates pain or discomfort when attempting to achieve physiological ranges of neck motion, it is advised to abstain from training and refer the individual to a licensed healthcare professional.

Maintaining the head and neck in neutral alignment (to slight extension) with the torso is an important facet to provide the athlete with a strong, balanced set-up and point of reference throughout the squat.( 6) Incorrect positioning of the head and neck may negatively cascade into improper spinal positioning and tracking throughout the range of the movement.( 6) In theory, the spine, although comprised of many vertebral links, acts as a single entity. A change in alignment in one section of the spine may influence compensation in another section. Furthermore, poor body alignment as a result of incorrect head position may predispose an athlete to injury during more intense squat exercises.( 6, 15)

Practitioners should be aware that head position and gaze direction (focal point) are related but independent. Gaze can be directed by keeping fixed eyes and moving the head, or by moving the eyes independently of a fixed head.( 6) Both head position and gaze have been shown to influence spinal kinetics and kinematics.( 43)

Desired Technique

Head Position

The athlete's head should be maintained in a neutral position (to slight extension) in relation to the spine (). The neck should be held in line to the plane of the torso.

Gaze

Point of focus for gaze is instructed to be either straight ahead or slightly upward ().( 6) It is hypothesized that athletes may have a tendency to move in the direction of their gaze and therefore a downward gaze is not recommended during ascent. A slightly upward gaze during ascent may help guide an athlete to lead with their head and chest rather than raising their hips first when beginning the concentric portion of the squat. In addition, a slight upward gaze throughout the movement may help prevent excessive forward trunk flexion.

Common Deficits

Head Position

Most athletes will be able to achieve proper head position during the initial set-up phase for the squat. Muscle strain or injury to the cervical vertebrae during exercise may result from improper neck position. Therefore, movement of head too far forward or backward as well as movement of head laterally to either side should be explicitly avoided. Excessive tilting of the head backward into a position of extreme cervical hyperextension can be dangerous during the squat, particularly when heavy resistance is integrated.( 2) Excessive cervical hyperextension may be a compensatory movement for a lack of thoracic extension. Excessive cervical flexion may also result in a greater tendency to extend the lumbar spine, which can increase lumbar compression forces (). Conversely, if head position is directed too far downward into cervical hyperflexion, a significant increase in hip and trunk flexion may result as a compensation mechanism, which is not considered an optimal movement strategy for the back squat and other sport activities such as tackling in football.( 6) From the posterior perspective, ensure that the athlete's neck position is perpendicular to the line of the shoulder and there is minimal lateral head tilt in either direction. If an athlete is unable to maintain his or her head and neck in a neutral position throughout the entire squat, the deficit may either be due to neck muscle weakness (i.e., trapezius muscles) or inadequate postural awareness.

Gaze

Gaze can either be directed too high or too low. A downward gaze has been shown to increase hip flexion and potentially trunk flexion in comparison to an upward gaze (). This position may place increased torque on the vertebral column.( 2, 6, 43) However, it is important to disassociate gaze from head position. Although gaze can be slightly upward, the head position should not deviate from neutral. Most errors concerning gaze direction can be corrected via verbal and visual cueing.

2. Thoracic Position

The athlete must be able to demonstrate adequate postural stability and control of the upper torso as optimal squat technique favors a rigid spine that does not concede to any planar motion. Stable, upright posture should be sustained throughout the movement as a more vertically positioned upper spine, contracted upper back musculature, and chest up position reduces shear forces on the intervertebral disks.

Desired Technique

It is preferred that the thoracic spine is slightly extended and held rigid.( 3) The chest is directed outward and upwards to bring the torso angle to a more vertical position,( 3) and this position should be maintained throughout the entire squat movement. The chest can be positioned upward independently of trunk angle (criterion 3). The scapulae should be held retracted and depressed while the glenohumeral joint maintains a position of relative external rotation, which pushes out the chest and keeps the upper torso erect (). As a result, the shoulders will assume a slightly rolled back position. The athlete's forearms should be held parallel to their spine and the shoulders should be retracted and not rolled forward. This position allows for major supporting back muscles (i.e., latissimus dorsi, erector spinae, trapezius, rhomboids) to contribute maximally to spinal stability.( 28) In addition, a tight upper back with retracted scapulae can help provide the athlete with a favorable position to rest the dowel in the most secure and comfortable manner during back squats.( 28)

3. Trunk Position

Trunk stability and control are derived from the lower back musculature, obliques, lumbar paraspinals, quadratus lumborum, and abdominals. The body's core is a critical modulator of lower extremity alignments and loads during dynamic tasks such as squatting.( 33) The stabilizers of the trunk and hip can preactivate to counterbalance unwanted trunk motion and regulate lower extremity postures during the squat.( 33) Decreased core stability and muscular synergism of the trunk and hip stabilizers negatively affect performance in power activities and may increase the incidence of injury due to lack of control of the center of mass.( 14, 33) The squat exercise can help instill mechanics that improve trunk stability during dynamic tasks.

Stability during the squat is enhanced with muscular stiffness of all muscles around the lumbar spine. Failure to stiffen the lower back musculature, combined with poor lifting mechanics, increases the potential to overload spine and back tissues to the point of injury, especially when repeated over time.( 27, 29) A more upright lumbar posture increases load onto lower extremity levers, which may reduce low back stress. Some may dismiss the need to preserve the neutral curvature of the lumbar spine when squatting. However, this is problematic as the spine loses its ability to bear load when the neutral curve is lost, which prevents eventual progression of the squat with load while maintaining a reduced injury risk. In summary, the individual must demonstrate the ability to maintain a stiffened torso with a neutral, lordotic lumbar position as a safe and optimal squat strategy.

Desired Technique

The lumbar vertebrae are maintained in a neutral alignment throughout the entire squat movement.( 28) This entails maintaining a slight lordotic curve in the lumbar region while holding the abdomen upward and rigid to promote stability (). The trunk should remain as upright as possible during the squat to minimize lumbar shear forces associated with forward lean.( 28) Furthermore, the trunk should remain stable throughout the squat without any observation of wavering or displacement. A general guideline to ensure adequate trunk posture is to necessitate that the line of the trunk is maintained parallel to the line of the tibias from the lateral perspective. However, this guideline also necessitates proper foot and knee position.

Common Deficits

The squat requires sufficient spinal mobility to assume and maintain slight lordotic posture. Otherwise, an individual may tend to take forward posture and place excessive pressure to the lower back, especially if their head is tilted forward as well. Insufficient hip mobility may also negatively affect the ability to preserve a lordotic spine, which may be due to genetics, prior injury, or tight connective tissues. If the athlete flexes at the spine before 120° of hip flexion when squatting, they may have restriction in the posterior fibers of the illiotibial band or lack of lumbar control.

Observation of a rounded spine, or kyphosis, due to relaxed back musculature and spinal flexion indicates a deficit for the BSA (). If an athlete does not stiffen the back musculature to support the spine positioned in a neutral, slightly lordotic position, increased and potentially harmful compressive and shear forces of the lumbar spine may result during more intense squat variations.( 28) The risk of disc herniation is increased during heavy resistance squatting with the spine in a flexed position as a result of excessive stress placed on intervertebral discs.( 26, 43)

The most critical component to correcting a deficit with the lumbar spine and abdomen is identification of the mechanism driving the failure to desired technique. Due to the complex nature of this area, one, or a combination of problems could exist. Having the athlete execute a squat to at least parallel with only a dowel as the external resistance will allow the coach to gauge when and if the athlete presents a movement pattern including excessive anterior or posterior pelvic tilt. If the athlete is unable to maintain a slight lordotic curve in the lumbar spine and keep the trunk angle parallel with the tibial angles, then specific corrective actions should be taken (Part 2).

Domain 2: Lower Body

Domain 2 encompasses the musculoskeletal components and positions of the three major joints of the lower extremities during the back squat.

4. Hip Position

The hip joint is a ball-and-socket joint capable of motion in all three planes. It is responsible for providing a pathway of the transmission of forces between the lower extremities and the pelvis during squatting.( 43) Evidence suggests that maintaining a neutral pelvic tilt during the squat increases activity of the erector spinae and oblique muscles, helping to ensure optimal muscular support for the spine while handling loads, thereby reducing the risk for low back injury.( 5)

The gluteus maximus is the largest muscle of the hip. During the squat movement, the gluteus maximus extends the femur and stabilizes the pelvis.( 43) The squat can be an effective training exercise to promote the development of gluteal strength, which is important for athletes as these muscles are prime movers in dynamic sports related movements such as running and jumping.( 33) Furthermore, without proper recruitment of the gluteal muscles, other muscle groups such as the quadriceps, must bear the load of the squat, which is suboptimal and may increase the risk of muscle imbalance and injury. The hamstrings are an assemblage of three muscles, including the biceps femoris, semitendinosus and semimembranosus, which originate on the pelvis and insert at the tops of the bones of the lower leg.( 43) Since the hamstrings cross both the hips and knees, they moderate movements at both joints.( 33) During descent, the hamstrings can assist the gluteal muscles by controlling flexion at the hips.( 43) In the ascent phase of the squat, the hamstrings contract to extend the hips. The hip adductors, muscles on the inner thigh, stabilize the femurs during the squat. They prevent the knees and hips from rotating inward during descent.

Desired Technique

The athlete maintains square, stable hips with minimal mediolateral movement during the squat (). Squat depth should be determined based on the position of the hips.( 2) The position of the femurs should remain symmetrical throughout the entire exercise.( 2) It is optimal if the line of the hips from the frontal perspective is parallel to the ground. The athlete is also encouraged to maintain the pelvis in normal/neutral tilt, particularly during the descent phase of the movement. This is particularly important in the final part of the descent.

5. Frontal Plane Knee Alignment

Internal knee force response to external loads are primarily generated by the quadriceps, hamstrings, and gastrocnemius.( 43) Tibiofemoral compressive forces help resist anteroposterior shear forces and translation.( 43) Tibiofemoral and patellofemoal compression has been shown to increase with increasing knee angle as a protective function at the knee by initiating a co-contraction between the quadriceps and hamstrings.( 43) Therefore, closed kinetic chain exercises such as the back squat exercise may support appropriate rehabilitation exercise post ligament reconstruction surgery.( 16) Although shear forces tend to increase with increasing knee angles, forces on the cruciate ligaments of the knee decrease at high flexion angles.( 43) Thus, there is no known evidence to support the contention that squat depth below parallel increases the potential for injury to the cruciate and collateral ligaments and menisci in the knee during deep flexion.( 43) Training with the squat exercise may enhance passive and dynamic knee stability in deep knee flexion positions via active muscular protection of the passive structures during sport movements.( 7, 8, 19, 39)

Desired Technique

The knees should track over the toes throughout the squat motion visually evident as a neutral frontal plane knee position throughout the movement (i.e., the foot is positioned to create a perfect in-line hinge with knee motion). There should be an absence of knee displacement both medially and laterally. The lateral aspect of the knee should not cross the vertical plane of the medial malleolus when assessing for medial displacement (). While the goal position is to have the tibia in vertical alignment perpindicular to the floor with error towards lateral knee positions, the medial aspect of the knee should also not cross the vertical plane of the lateral malleolus.

Common Deficits

Excessive mediolateral movement of the knees signals a functional deficit. Valgus or varus frontal plane movement can be attributed to poor neuromuscular control and lack of function or strength of the lower extremity musculature, especially the posterior chain complex. Knee valgus (medial or knock-kneed movement) during the squat may be influenced by decreased hip abductor and hip external rotation strength, increased hip adductor activity and restricted ankle dorsiflexion. ( 4) Observed valgus during the squat may due to a suboptimal active neuromuscular pattern of the athlete. Active valgus, which is a position of hip adduction and knee abduction as a result of muscular contraction, is often the underlying cause for observed dynamic valgus during the back squat. From an observational standpoint, medial knee motion is a much more common deficit relative to knee varus (outward movement of the knee). However, knee varus can occur and is sometimes a compensatory strategy employed by athletes with flat feet. A neutral knee alignment is desired and feedback should be given to correct varus or valgus positioning during the movement. Knee valgus can be identified by observation of the medial aspect of either knee passing the medial malleolus from the anterior perspective during any phase of the squat ().

6. Tibial Translation Angle

As a general rule, increased anterior tibial translation increases torque about the knee joint. ( 16) Although this observation has led some practitioners to caution against allowing the knees to travel past the toes, there is no known evidence that a defined point exists whereby injury risk exceeds the potential benefits during the squat exercise. Moreover, a conscious effort to restrict forward translation has been shown to increase forward trunk lean, resulting in significantly greater forces at the hip and spine that place these joints at greater risk of injury. ( 16, 23) Thus, on the proviso that feet remain firmly fixed on the floor, anterior tibial translation angle should be unrestricted with the focus on initiating the squat descent by breaking the hips back. ( 16) Adequate tibial translation angle is able to be achieved via normal foot and ankle capsular mobility, soft-tissue flexibility and proper joint mechanics.

Desired Technique

Although the general goal should be to maintain a positive shin angle, this objective should be accomplished by proper hip joint kinematics. ( 16, 45) The knees therefore should move freely in accordance with hip range-of-motion. The extent of anterior tibial translation will vary between individuals depending on anthropometrics, in particular the torso and leg length ratio. As a general guideline, the athlete should attempt to match tibia angle in parallel with an upright trunk, while keeping their heels on the ground ().

Common Deficits

Athletes may either demonstrate excessive translation or excessive restriction of the tibial progression angle (). Excessive anterior translation of the knees over the toes is purported to increase shearing forces on the knee and as well as greater knee extensor torque. ( 30) Overly restricted tibial translation during the squat increases anterior lean of the torso, which accompanies increases in hip torque and lumbar shear forces. ( 16) The optimal position of tibial progression angle may support active muscular recruitment of the lower extremity while avoiding unwanted stresses on the passive structures. Often weak gluteal muscles influence the body to use a strategy to alternatively place load on the knees increasing tibia progression rather than on the rear. ( 33) Excessive tibial progression angle can also be exacerbated by weakness in calf and soleus, weak hamstrings, or quadriceps dominance. Restricted motion of the gastrocnemius and soleus muscle complex via the Achilles tendon, talocrural joint restrictions at the posterior ankle, restrictions in hip mobility, and deficits in foot mobility may also hinder proper tibial progression angle. An evaluation by a licensed healthcare provider may be necessary if a good stretching and mobility routine for the posterior calf musculature does not improve proper performance.

7. Foot Position

Adequate ankle mobility supports a balanced and controlled squat movement. However, foot and ankle position can be influenced by proximal forces as well, which may need to be ruled out to determine the cause of the movement deficit. The ability of the athlete to maintain a flat and stable foot position during the back squat necessitates adequate ankle dorsiflexion. ( 3)

Common Deficits

Ankle inversion or eversion during the squat is also indicative of a biomechanical deficit. Although pressure should be emphasized toward the lateral side of the foot, the medial side should not come off of the ground to promote balance and stability. The calcaneus should not appear everted relative to the lower leg. ( 20) Stiffness in the ankle joint from poor dorsiflexion may cause the foot and the knee joints to compensate. ( 3) These compensations may have a negative impact to foot and knee stability that is needed for correct squat mechanics.

Furthermore, weakness in the ankle musculature has been implicated in faulty movement patterns during the squat. A lack of strength in the medial gastrocnemius, tibialis anterior and/or tibialis posterior decreases the athlete's ability to control knee valgus and foot pronation motions, and may contribute to excessive medial knee displacement and dynamic valgus. ( 1) While increasing ankle mobility, and in many cases hip mobility, is the desired endpoint for this deficit, some athletes may benefit initially from the use of a heel block to aid in creating a stable platform and assist in pushing through the heels.

Domain 3: Movement Mechanics

Domain 3 analyzes the kinematics of the squat and discusses the limitations of functional deficits on proper movement mechanics. Triple extension (extension of ankle, knee and hip) and flexion movement patterns are inherent to sports associated movements such as jumping and landing mechanics.

8. Descent

After achieving a proper set-up, the athlete is instructed to initiate the squat movement with the descent phase. Throughout the descent, the athlete should maintain full control of their velocity and descending position. The athlete should descend by flexing the hip, knees and ankles in a fluid, coordinated movement as the body is lowered in a controlled manner.

Desired Technique

The descent is initiated with the breaking of the hips ('hip hinging') while maintaining a rigid, upright trunk. Breaking the hips at the initiation of the squat movement migrates the load to the and posterior chain, which is a more safe strategy for the knees and lumbar vertebrae. ( 33) The athlete should reach back as if sitting in a chair that is slightly too far away as they descend to the desired depth. The goal should be for the athlete to keep their rear as far away from their ankles while maintaining an upright torso throughout the squat. The vertical distance between the athlete's shoulders and hips should remain constant throughout the entire descent. Body weight should be transferred to and supported by the athlete's posterior chain musculature, particularly the hamstrings and gluteals, and not placed anteriorly on their knees (). The descent of the squat should move back in a vector that remains at a constant downward angle The athlete should move at a controlled tempo with no less than 2:1 (descent: ascent) up to a 4:1 ratio in regard to velocity of the eccentric movement compared to the concentric ascent phase.

Common Deficits

Observation of excessively rapid or unsteady movement of the body during descent should be considered a deficit. In addition, incorrect descent mechanics may also be noted if the athlete does not maintain constant speed and control during the entire eccentric phase, which is particularly common in novice lifters. ( 31) Furthermore, a common mechanical deficit is for athletes to place load down on the anterior aspect of the knees rather than back on the hips during decent (). Typically this incorrect strategy can be observed with, but not limited to, excessive tibial progression angle (Criteria 6) and/or heels coming off of the ground (Criteria 7). This incorrect descent strategy may place excessive shear forces on the anterior knee and decreases recruitment of the posterior chain musculature. Athletes with insufficient posterior chain (i.e. hamstrings, gluteals) strength may be more likely to lose descent control toward the later phases of the movement and may favor a knee loading strategy. In addition, more intense squat variations, such as high velocity eccentric movements, can be dangerous if the muscles are forced to stretch too greatly in a short amount of time. Practicing and mastering controlled descent strategies support the development of strategies that can mitigate risk of training induced injuries.

9. Depth

Squatting to appropriate depth is a critical component in deriving the full benefit of the activity. Without squatting to the proper depth, the hamstrings and gluteus muscular complex may not be adequately challenged. Specifically, training at shallower knee flexion can influence quadriceps dominant sport skill performance that can limit performance and increase injury risk. ( 19, 39) Likewise, training at deeper depths will help benefit motor control positions that are common to sport. The skill and strength gains achieved during deep knee and hip flexion positions may help reduce quadriceps dominance strategies that are purported to increase injury risk. ( 18, 37, 38) As noted previously, evidence that indicates squatting below parallel increased the potential for injury to the cruciate and collateral ligaments or menisci in the knee during extreme flexion does not exist. ( 43) The squat exercise may enhance active knee stability if performed correctly and may reduce sport injury risk to the passive structures of the knee. ( 7, 8, 39)

Common Deficits

The most common deficit of depth during the back squat is from the athlete squatting too shallow (). While squatting excessively past parallel can occur it is not often detrimental to the athlete. If contraindicated based on existing pathology, excessive squat depth can be easily corrected with cueing and feedback. The athlete may lack isometric strength of the posterior chain to maintain bodyweight support at the apex of depth. Furthermore, tightness in the posterior chain musculature and hip adductors may further limit the ability for an athlete to achieve appropriate depth.

10. Ascent

The ascent of the squat should follow the same path as the descent in the reverse direction. The primary diver of ascent should be the hips and weight should be kept of the heels and lateral sides of the feet. The torso of the athlete should remain fairly static throughout the ascent as the ankles, knees, and hips extend into the original position.

Desired Technique

The torso should remain upright during the entire ascent phase. The shoulders and hips should rise at the same pace and the difference in vertical height of the shoulders and hips should remain constant (). The back is to be kept in a rigid, tight position with stiffened muscles and with the lumbar spine in a neutral to slightly extended position. The athlete should utilize a hip drive strategy as the primary driver for the ascent. The athlete should only exhale once the ascent has been completed.

Common Deficits

Common faults in early stages of learning the back squat (i.e., early training age) are for the hips to rise faster than the shoulders, which would increase trunk flexion (). If the hips rise too quickly, the vertical distance between the hips and shoulders will decrease during the early ascent phase (). Irrespective of the load, the movement pattern represents an incorrect back squat that can be a dangerous strategy to the lower back during squatting with progressive external resistance. In addition, relative to the downward descent, a large deviation in the movement pattern employed during upward ascent is also considered a deficient technique.

Knee position during ascent may also greatly influence mechanics. If the knees are too far back in relation to the trunk, the athlete is forced to lean forward with their torso to stay in balance. If the knees are too far forward, an acute shift of postural balance occurs, requiring the athlete to shift their body weight onto their toes instead of their heels. This strategy influences an inefficient hip drive out of the transition phase of the movement. Typically, mechanical deficits of ascent are due to sub-optimal motor recruitment patterns that can be improved through neuromuscular training and corrective cueing feedback.

Addional Considerations for the Squat

Anatomical Variation

The proposed form and technique in the 10 BSA criteria are meant to be set as an ideal standard for all athetes. However, it is understood that anatomical variation may predispose some athletes to have disadvantages in achieving these desired positions and mechanics. The factors of anatomical variation most influencing the squat are the anatomy of the hip, together with the ratio of torso length to leg length. The shape of the hip joint determines the type and incidence of specific hip pathology, and squat depth. While a deeper hip joint increases standing stability to the joint, it prevents the femur from flexing into a deep squat without pinching the hip joint labrum and joint capsule. This bony restriction nullifies any attempt to stretch or mobilize the joint to perform the deep squat. Assessment of this feature begins with the individual kneeling on their hands and knees. The knees are initially placed together. Then the pelvis is rocked back towards the heels. The test stops when the neutral spine curvature begins to flex. Then the knees are spread apart a few inches and the "pelvic rock" test is repeated and the depth of the kneeling squat is noted. In this way, the ability to deep squat without compromising the back curvature is quantified, together with identifying the optimal width for the feet and knees when squatting.

Other suggestions for squat safety involve knee loading and whether the knee may be allowed to travel ahead of the toe. This also is a function of the leg length and torso length ratio. A 7 foot tall basketball center usually has longer legs than torso, such that the knees travel way ahead of the toes. The length of the femur creates a long lever and a high patellar tendon load. Generally, these athletes squat with their hips back to balance the knee and hip loads. In contrast, an individual with a longer torso to leg length ratio squats with more emphasis on knee motion, and the shin remains parallel to the torso, equally sharing hip and knee loads.

Integrating the Squat into Athletic Preparation Training

Participation in organized sports does not safeguard youth from developing poor or inefficient movement patterns. Athletes who do not demonstrate proper mechanics may utilize compensatory movement strategies that can hinder their athletic performance and heighten their risk of sports-related injury. ( 4, 24) In the absence of pressures or cueing during activity to modify these inefficient movements, athletes will continue to master and imprint these suboptimal strategies that will likely propagate into movements utilized in sport competition. Non-athletes with poor squat mechanics will more likely suffer the same fate of eventual pain and sub-optimal performance. The back squat offers an opportunity to teach and instill a correct functional movement pattern providing the foundation upon which to build strength and mobility abilities. For example, it is suggested that the squat reflects lower extremity movement patterns often required for success in explosive sport techniques that are likely to expose the lower extremity to high joint loads. ( 4) Improved strategies to help young athletes absorb, redirect and create explosive squat related movements can help enhance performance outcomes and reduce injury risk factors. ( 36, 39) On a more broad level, preservation of the competency to squat can prolong independent living in older adults.

Proficiency with the back squat is a prudent prerequisite to heavy resistance squat training, especially for young athletes with a low training age. ( 35) An individual should be able to display perfect back squat technique consistently before moving on to more advanced squatting variations including depth jump plyometric training. In addition, by developing proper squat mechanics before utilizing external resistance, an athlete can minimize the potential to instill improper compensatory strategies and decrease the risk of training related injuries. ( 34) It is outside the scope of this review to discuss the many useful technical variations of the squat movement (i.e., sumo squat, front squat). However, it is advised that athletes do not increase the intensity of the squat (i.e., increase resistance) unless the athlete can demonstrate consistent, proper form of the back squat. Specifically, the back squat is utilized first in the battery of squat variations to teach the parent movement pattern and identify functional deficits. If taught and progressed correctly, technique should remain the same as exercise intensity is increased. Part 2 of the discussion will detail corrective strategies to target specific functional deficits identified during the squat.

It should be noted that the back squat is only one recommended component of a comprehensive neuromuscular training program for youth. Integrative neuromuscular training targeted for the physical development of youth should consider a variety of cognitive- and training-age appropriate exercises to adequately prepare a child for the rigors of moderate to intense physical activity. ( 34, 40) Integrative neuromuscular training programs for youth should be appropriately designed to meet the needs and goals of aspiring young athletes while considering their current ability level. ( 24) It is highly recommended that qualified integrative neuromuscular training professionals who understand the psychosocial uniqueness of youth design contribute to the design, supervision and implementation of training programs for young athletes to minimize the risk of training-related injuries and to promote acquisition of sound exercise technique. ( 24, 34) Integrative neuromuscular training programs for youth are most effective when designed and progressed to be safe and training-age appropriate. ( 11, 34, 35, 41)

Biographies

# data[].attributes.attachment_link.title
The back squat: A proposed assessment of functional deficits and technical factors that limit performance

# data[].attributes.attachment_link.description
Fundamental movement competency is essential for participation in physical activity and for mitigating the risk of injury, which are both key elements of health throughout life. The squat movement pattern is arguably one of the most primal and critical ...

# data[].attributes.headline
8) Band tension and chains for upper body

# data[].attributes.subject
8) Band tension and chains for upper body

# data[].attributes.attachment_link.readable_text
Abstract

Purpose

To determine the impact of inclusion of a band or chain compensatory acceleration training (CAT), in a 5-week training phase, on maximal upper body strength during a 14-week off-season strength and conditioning program for collegiate male athletes.

Patients and methods

Twenty-four National Collegiate Athletic Association (NCAA) collegiate baseball players, who were familiar with the current strength and conditioning program and had a minimum of 1 year of formal collegiate strength and conditioning experience, participated in this off-season training study. None of the men had participated in CAT before. Subjects were matched following a maximal effort (1-repetition maximum [1-RM]) bench press test in week 1, then were randomly assigned into a band-based CAT group or a chain-based CAT group and participated in a 5-week training phase that included bench pressing twice per week. Upper body strength was measured by 1-RM bench press again at week 6. A 2 × 2 mixed factorial (method × time) analysis of variance was calculated to compare differences across groups. The alpha level was set at P<0.05.

Results

No difference ( F 1,22=0.04, P=0.84) existed between the band-based CAT and chain-based CAT groups. A significant difference was observed between pre- and posttests of 1-RM bench ( F 1,22=88.46, P=0.001).

Conclusion

A 5-week band CAT or chain CAT training program used in conjunction with an off-season strength and conditioning program can increase maximal upper body strength in collegiate baseball athletes. Using band CAT and/or chain CAT as a training modality in the off-season will vary the training stimulus from the traditional and likely help to maintain the athlete's interest.

Keywords: variable resistance, band, baseball, chain, resistance training

Introduction

Successful skill execution in baseball often requires the development of force over a short period of time. Strength is critical to developing force rapidly and is integral to the baseball skills of batting, throwing, and running. Consistent strength training has been shown to lead to an increased throwing velocity 1, 2 and bat swing speed 3, 4 in baseball athletes. The importance of strength, power, and agility, in relation to batting and fielding performance, has been demonstrated, 5, 6 and it has been recommended that their development be the focus of off-season strength and conditioning training programs. 7

Upper body strength is believed to be important in baseball, and as such, the bench press is commonly included in resistance training programs for baseball athletes. 1, 3, 8, 9 The Olympic/"free bar" bench press is considered to be an optimal exercise for developing upper body musculature, and a variety of bench press methods have been included in off-season training programs, with the goal of improving maximal upper body strength. 8, 10- 12

Compensatory acceleration training (CAT), which is the process of attempting to achieve maximal acceleration with a moderate to high load, 13, 14 has been shown to be effective for increasing maximal upper body strength. 15 This training technique, also referred to as intended maximal concentric acceleration (IMCA), has been used by powerlifters, 14, 16- 18 football players, 15 and baseball athletes 19 for lower- and upper-body muscular strength and power development. The ability to complete the same amount of work in a shorter time frame leads to an increased rate of force development, 12 which is essential to a power sport like baseball. When using CAT or IMCA training, it is recommended that the athlete receives verbal instruction to move the weight quickly as the exercise is performed. 15- 19

Accommodating resistance (AR) or variable resistance training methods permit the weightlifter to maintain movement velocity throughout the complete range of motion, by providing decreased total resistance at the point of weakest leverage for the muscle joint or "sticking point" within the exercise. 10, 20 Training with AR methods, such as elastic bands and weighted chains, will minimize the amount of deceleration at the end of the concentric portion of the lifting exercise, thereby permitting an extended period of acceleration and an improved rate of force development. 12, 16- 18, 21 Additionally, performing the bench press with AR is thought to minimize stress, due to the variable resistance throughout the range of motion, 8, 16- 18 which could be advantageous when training athletes from sports (eg, baseball, tennis) that place increased stress and strain on the shoulder joint.

Although previous research has demonstrated increased velocities when performing the bench press with weighted chains, 20 results from intervention studies in which AR methods were used have been inconclusive. No group differences were found in posttesting of maximal strength following a 7-week training program in which collegiate football players bench-pressed with either elastic bands or weighted chains. 11 McCurdy et al 8 reported similar findings to the aforementioned study, 11 following a 9-week training program using chain bench press, in baseball athletes. Conversely, significant gains in maximal upper body strength were observed in collegiate basketball, hockey, and wrestling athletes after a 7-week training program of elastic band bench press compared with one of plate-loaded barbell bench. 10

At present, training with CAT methods appears to increase maximal strength, 15, 19 while the effects of including AR techniques in the training programs of athletes are indeterminate. 8, 10, 11 Additionally, there is a paucity of research in which CAT and AR training methods have been combined in a resistance training program, yet this type of resistance exercise programming is commonly accepted and employed by practitioners. Previous research has clearly demonstrated that regular resistance exercise will increase muscular strength, 1, 2, 8- 12 but the optimal training period and method for such increases has not been elucidated. Therefore, the purpose of the current study was to examine the effect of a 5-week resistance training program in which CAT was used in conjunction with the AR techniques of elastic bands and weighted chains, to determine the effect on maximal upper body strength in collegiate baseball athletes.

Material and methods

Experimental approach to the problem

This study was designed to determine the impact of the inclusion of an AR elastic band ("band") or AR weighted-chain ("chain") CAT phase, on maximal upper body strength, during an off-season strength and conditioning program for collegiate baseball. Subjects were matched following a maximal effort (1-repetition maximum [1-RM]) bench press test, then were randomly assigned into a band CAT group or a chain CAT group. The athletes were under the direct supervision of a Certified Strength and Conditioning Specialist (CSCS) while they participated in a 5-week training phase that including bench-pressing twice per week. The 5-week band CAT or chain CAT phase was part of the larger 14-week off-season training program and occurred during weeks 6-10. The athletes were experienced lifters who were familiar with the resistance training exercises included in the program and the maximal strength tests that were administered during the testing sessions. Upper body strength was measured by 1-RM bench press testing "pre" (week 5 of 14) and "post" (week 11 of 14) intervention. Adequate recovery time was provided between warm-up sets and maximal attempts.

Subjects

A total of 24 National Collegiate Athletic Association (NCAA) collegiate baseball players who were familiar with the current strength and conditioning program and had a minimum of 1 year of formal collegiate strength and conditioning experience volunteered to participate in this study. None of the men had participated in band CAT or chain CAT training before this study. All were medically cleared for Intercollegiate Athletic participation and completed a medical history form; all had the risks and benefits explained to them beforehand and signed an institutionally approved consent form to participate. The George Mason University Institutional Review Board for Human Subjects approved all study procedures. Sustaining a musculoskeletal injury of the upper body or spine that prevented sports participation within 6 months prior to the study was grounds for exclusion from the study. Prior to strength testing, body height (Seca Stadiometer; Seca GmBH, Hamburg, Germany), and body mass and body composition (Tanita BC-418; Tanita Corporation of America Inc., Arlington Heights, IL, USA) were determined. Subjects were instructed to refrain from upper body exercise for 48 hours prior to each training or testing session. In an effort to maintain consistency across testing conditions, each subject was asked to consume his own identical diet for 24 hours prior to the pre- and posttesting sessions and to consume nothing but water (as needed) for 2 hours prior to the two testing sessions. Training and testing sessions for all subjects were conducted under the supervision of a CSCS, during the off-season training period.

Procedures

1-RM maximum strength

For evaluation, 1-RM bench press testing was conducted twice, to determine upper body strength. Pretesting occurred 1 week before the start of the 5-week band CAT or chain CAT program, in what was week 5 of the 14-week off-season training program. Posttesting took place following completion of the 5-week training phase, in what was week 11 of the 14-week off-season training program. Before beginning testing, the athletes completed a specific dynamic flexibility warm-up, which they were familiar with from off-season strength and conditioning training. Next, athletes completed a supervised (by the CSCS) warm-up before testing, to ensure that the intervention exercises were performed correctly. Standard weight lifting power racks (Power Lift ®; Conner Athletic Products, Inc., Jefferson, IA, USA) were used for the 1-RM tests. The athletes took a timed rest of 3 minutes between maximal attempts. Weight was increased based upon the performance of the previous attempt, and the athlete continued to perform maximal effort attempts until failure or until it was determined the lifting form was compromised. After two failures, testing was stopped, and the best lift was recorded.

Off-season strength and conditioning training program

The athletes followed a 5-week band CAT or chain CAT bench press training phase that was included as part of the larger 14-week off-season strength and conditioning program designed and implemented by the CSCS who was assigned to baseball. Each group (ie, the band CAT and chain CAT groups) followed the same "periodized", strength training program. All the athlete participants trained together as a team, in the varsity weight room during the baseball off-season (September-December). Specifically, the athletes performed two whole-body lifting sessions, separated by 48 hours, per week for a total of 10 sessions over the 5-week training phase. Training sessions occurred at the same time and on the same days each week. To remain in the off-season program, the athletes were required to make up any missed workouts under the direction of their CSCS within 1 week of being absent. No workouts were missed during the 5-week band CAT or chain CAT training phase. Athletes were asked to notify their CSCS immediately of any concerns, discomfort, pain, or injury related to the training methods. No such issues were raised.

Weight selection for the weekly workouts was based upon percentages from pretesting. Bench pressing occurred during both weekly lifting sessions. Day 1 (CAT maximal effort day) incorporated the periodized protocol for the bench press based on the previously determined 1-RM bench press, and the training intensities ranged from 43%-97% 1-RM. The training intensity for day 2 (band CAT or chain CAT) remained at 50% 1-RM for the 5-week phase. All subjects completed a total of five CAT maximal-effort and five band CAT or chain CAT bench press workouts during the training period. On both days, verbal instructions were given following the eccentric phase of each bench press repetition "to move the weight as fast as possible". Following the warm-up, the workout exercise order progressed from larger muscle groups to smaller muscle groups. The exercise selection and program design characteristics are listed in .

The accommodating resistance and compensatory acceleration training methods

Following the 1-RM bench pretest, athletes were matched according to their strength scores, then randomly assigned to either the band CAT or chain CAT group. During the second bench day of each week, bands (Jump Stretch, Inc., Youngstown, OH, USA) and chains (EliteFTS, Inc., London, OH, USA) were attached to the bench press apparatus in a similar manner to what has been described previously. 8, 10, 11 The appropriate number of training chains (10 lb) and support chains (2 lb) were equally distributed across both ends of the barbell to represent a total load of 50% 1-RM for chain CAT training. A similar procedure was followed for the band CAT training, with bands attached whose maximal resistance when extended, plus the barbell, represented a total load of each individual subject's 50% 1-RM. The amount of band resistance was determined according to the equipment company's specifications. Both band CAT and chain CAT groups performed nine sets of three repetitions at 50% 1-RM, with instructions to move the weight as quickly as possible. The bar grips consisted of close grip (hands 14 inches apart) for sets 1-3, midgrip (hands 19 inches apart) for sets 4-6, and wide grip (hands 24 inches apart) for sets 7-9. The rest period between each bench set of the band CAT or chain CAT workout was 45 seconds.

Statistical analyses

Descriptive statistics were computed for each of the variables. Independent group t-tests were conducted on the characteristics of the subjects. To evaluate changes from pretest to posttest in the dependent variable, a 2×2 mixed factorial analysis of variance was calculated to compare the dependent variable (Bench Press) across groups (band CAT and chain CAT) and testing periods ("pre" and "post"). The alpha level was set at 0.05. All the statistical procedures were conducted using the Statistical Package for the Social Sciences (SPSS Statistics for Windows, Version 20.0; IBM Corp, Armonk, NY, USA).

Results

The primary purpose of this research was to determine whether differences existed between maximal upper body strength following inclusion of 5 weeks of band CAT or chain CAT into an off-season strength and conditioning programming, for a group of collegiate baseball players. The goal was to determine which method (band CAT or chain CAT) would produce greater increases in upper body strength over the 5-week training period.

All data are presented as means ± standard error of the mean. Twenty-four subjects completed the study. Their physical characteristics are recorded in . Subjects were matched according to their pretest bench press scores, then randomly assigned into the band CAT or chain CAT group. Independent group t-tests were completed to determine whether there were differences in physical characteristics between the band CAT and chain CAT groups. A significant difference existed ( P=0.02) in body fat percentage between the band CAT (13.0%±1.9%) and chain CAT (10.7%±1.6%) groups.

Table 2

Strength testing

The descriptive statistics for pre- and posttests of 1-RM bench press are presented in . There was no interaction effect between group and time ( F 1,22=0.00, P=1.00). No significant difference ( F 1,22=0.04, P=0.84) existed between the band CAT and chain CAT groups. A significant difference ( F 1,22=88.46, P=0.001) was observed between pretest (100.7±4.7 kg) and posttest (112.4±5.4 kg) of 1-RM bench as a result of the 5-week training phase. The band CAT and chain CAT groups increased their maximal bench press by 11.74 kg and 11.75 kg, respectively.

Discussion

This is the first study designed to examine differences in training using the AR methods of weighted chains and elastic bands while employing CAT lifting techniques in resistance-trained baseball athletes. The overall findings supported no difference between the two AR methods of upper body exercise. Results from previous research using these AR methods without CAT have been inconclusive. 8, 10

We observed that maximal upper body strength gains were similar between 5 weeks of band CAT and chain CAT training. Baseball athletes in both groups experienced a statistically significant increase in their maximal bench press from pre- to posttesting, with the band CAT group increasing 11.6% (ie, 11.74 kg) and the chain-CAT group increasing 11.8% (ie, 11.75 kg). These findings are consistent with previous research in which 7 weeks of AR training in football players produced an increase in upper body strength, with no group difference between elastic bands (+7.8%) and weighted chains (+7%). 11 Similarly, a 9-week AR intervention study, without the use of CAT, in baseball athletes resulted in increased upper body strength, with no group difference between weighted chains (+14.7%) or plate-loaded barbells (+6.3%). 8 On the other hand, 7 weeks of AR training with elastic bands, without the use of CAT, produced a significant group difference in upper body strength (+8%) compared with plate-loaded barbell training (+4%). 10

Although long considered to be a popular training method in the powerlifting community, 16- 18 there remains a dearth of published intervention studies on upper body strength and CAT. One intervention study used CAT techniques, without AR, for a 14-week off-season strength-training program with football athletes. 15 Significant group differences were observed, as the athletes training with CAT experienced a 9.4% increase in maximal bench press compared with a 3.8% increase in the control group. 15

It is unclear whether or not the increases in upper body strength in the present study were a result of the band CAT and chain CAT training methods or merely adaptations occurring as a result of consistent resistance training during the off-season. However, it is of interest to note that the upper body strength gains in the 5-week study are of a larger magnitude than those previously reported for longer training periods with football athletes. 22, 23 A linear periodized, 15-week off-season program for football athletes increased maximal bench press values by 7.8%, 22 while a 10-week planned nonlinear periodization program increased maximal bench press values by 4% in a similar subject population. 23 This finding from the current study is noteworthy because it indicates that combining AR methods with CAT techniques may result in a more rapid gain in maximal upper body strength (∼12%) than has been previously reported. A consistent goal of strength and conditioning professionals is to maximize results in minimum time; 24 therefore, they may find it beneficial to have athletes train using CAT in conjunction with AR for designated phases of the off-season strength and conditioning program. However, caution should be exercised in setting specific expectations for strength gains. Improvement may vary across sport, level of athlete, and length of the training phase. Further research is necessary to compare these training methods in more detail.

Resistance training is an accepted part of off-season training for baseball, with the primary goals being muscle strengthening 2, 3, 6 and injury prevention. 25 Shoulder injuries are common in baseball, due to the high volume of throwing, and while the bench press is generally considered to be an optimal exercise for developing upper body musculature, it has been reported to increase stress on the shoulder, particularly at the end of the eccentric phase. 26, 27 Performing the bench press with weighted chains is thought to minimize stress, due to the variable resistance throughout the range of motion. 8, 16- 18 Published research 8, 10, 11 as well as publications from the popular press 16- 18 caution against the risk of increased soreness when training with elastic bands. While soreness was not measured in the current study, athletes were instructed to report pain, injury, or increased soreness to the investigator. Neither the band CAT nor the chain CAT groups reported any incidence of the aforementioned symptoms.

We acknowledge some study limitations. First, the 24 collegiate baseball athletes had ≥1 year of formal collegiate strength training experience. Published research has shown that strength gains are affected by the type of training program and previous training experience. 12, 23, 28 Future study that addresses the relationship between training experience and upper body strength in connection with AR and CAT training methods is warranted. Second, the absence of a control group poses a limitation. Findings from previous AR training studies established significant upper body strength gains with elastic bands compared with plate-loaded barbells, 10, 28 yet in other studies, weighted chains failed to produce a greater strength gain than either elastic band 11 or plate-loaded barbell training. 8 Due to the limited number of trained baseball athletes available (ie, 24), a conscious decision was made to include only the two intervention groups - band CAT and chain CAT. Having a larger sample size would have been more conducive to the inclusion of a control group. Finally, the AR-CAT training was included as a 5-week training phase within the off-season strength and conditioning program as a whole, and the subjects were trained baseball athletes who were following sport-specific training regimens and involved in regular activities with definite neuromuscular demands. Thus, results may vary in untrained individuals or in athletes from other sports. Future research is needed to examine what role the training volume and intensities of other program exercises used in conjunction with CAT and AR methods may play in the upper body strength adaptations. Additionally, future examination of muscle activity patterns across these training methods may help to ascertain potential mechanisms of adaptation.

Conclusion

The results of this study suggest the following in trained collegiate baseball athletes:

1. The use of band CAT or chain CAT methods will increase maximal upper body strength.

2. AR and CAT can be implemented together as an effective training alternative for a 5-week phase during off-season programming.

3. The use of band CAT or chain CAT appears to be a viable, short-term training alternative since no concerns were expressed or injuries sustained.

Acknowledgments

The author would like to thank the athletic trainers, coaches, and student-athletes from the intercollegiate baseball program, for their contribution to the study.

Footnotes
Disclosure
The author reports no conflicts of interest in this work.

References

1. Lachowetz T, Evon J, Pastiglione J. The effect of an upper body strength program on intercollegiate baseball throwing velocity. J Strength Cond Res. 1998;12(2):116-119.

4. Spaniol FJ. Baseball Athletic Test: a baseball-specific test battery. Strength Cond J. 2009;31(2):26-29.

15. Jones K, Hunter G, Fleisig G, Escamilla R, Lemak L. The effects of compensatory acceleration on upper-body strength and power in collegiate football players. J Strength Cond Res. 1999;13(2):99-105.

21. Siff MC. Supertraining. 6th ed. Denver, CO: Supertraining Institute; 2003.

25. Lachowetz T, Drury D, Elliot R, Evon J, Pastiglione J. The effect of an intercollegiate baseball strength program on the reduction of shoulder and elbow pain. J Strength Cond Res. 1998;12(1):46-51.

26. Durall CJ, Manske RC, Davies GJ. Avoiding shoulder injury from resistance training. Strength Cond J. 2001;23(5):10-18.

# data[].attributes.attachment_link.title
Effect of compensatory acceleration training in combination with accommodating resistance on upper body strength in collegiate athletes

# data[].attributes.attachment_link.description
To determine the impact of inclusion of a band or chain compensatory acceleration training (CAT), in a 5-week training phase, on maximal upper body strength during a 14-week off-season strength and conditioning program for collegiate male athletes.

# data[].attributes.headline
7)  Matt Perryman's book on Squatting Everyday

# data[].attributes.subject
7)  Matt Perryman's book on Squatting Everyday

# data[].attributes.attachment_link.provider_name
ЖЕЛЕЗНЫЙ ФАКТОР

# data[].attributes.attachment_link.keywords[]
железный фактор

# data[].attributes.attachment_link.keywords[]
фитнес-бикини

# data[].attributes.attachment_link.keywords[]
пауэрлифтинг

# data[].attributes.attachment_link.keywords[]
спортивное питание

# data[].attributes.attachment_link.keywords[]
боевые искусства

# data[].attributes.attachment_link.description
железный фактор - форум по бодибилдингу, фитнесу, фитнес-бикини, фит-модель, пауэрлифтингу, тренировкам и спортивному питанию

# data[].attributes.body
How adding band tension affects velocity and power.

# data[].attributes.attachment_link.readable_text
Stevenson, Mark W ¹; Warpeha, Joseph M ²; Dietz, Cal C ³; Giveans, Russell M ²; Erdman, Arthur G ¹

doi: 10.1519/JSC.0b013e3181db25de

Stevenson, MW, Warpeha, JM, Dietz, CC, Giveans, RM, and Erdman, AG. Acute effects of elastic bands during the free-weight barbell back squat exercise on velocity, power, and force production. J Strength Cond Res 24(11): 2944-2954, 2010-The use of elastic bands in resistance training has been reported to be effective in increasing performance-related parameters such as power, rate of force development (RFD), and velocity. The purpose of this study was to assess the following measures during the free-weight back squat exercise with and without elastic bands: peak and mean velocity in the eccentric and concentric phases (PV-E, PV-C, MV-E, MV-C), peak force (PF), peak power in the concentric phase, and RFD immediately before and after the zero-velocity point and in the concentric phase (RFD C). Twenty trained male volunteers (age = 26.0 ± 4.4 years) performed 3 sets of 3 repetitions of squats (at 55% one repetition maximum [1RM]) on 2 separate days: 1 day without bands and the other with bands in a randomized order. The added band force equaled 20% of the subjects' 55% 1RM. Two independent force platforms collected ground reaction force data, and a 9-camera motion capture system was used for displacement measurements. The results showed that PV-E and RFD C were significantly ( p < 0.05) greater with the use of bands, whereas PV-C and MV-C were greater without bands. There were no differences in any other variables. These results indicate that there may be benefits to performing squats with elastic bands in terms of RFD. Practitioners concerned with improving RFD may want to consider incorporating this easily implemented training variation.

¹Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota; ²Laboratory of Physiological Hygiene and Exercise Science, School of Kinesiology, University of Minnesota, Minneapolis, Minnesota; and ³ Department of Athletics, University of Minnesota, Minneapolis, Minnesota

Address correspondence to Mark W. Stevenson, stev0258@umn.edu. and Joe M. Warpeha, warp0009@umn.edu.

Introduction

Force development is critical to the performance of virtually all sports and plays an integral role in key parameters such as velocity and power development (24). In particular, the generation of maximal muscular force (maximal strength) has been given considerable attention over the years in both the training and testing of athletes. Although this key component is clearly linked to athletic performance, the rate of force development (RFD; an index of explosive strength), power output, and speed development have been suggested by some to be equally, or more, important in predicting success in athletic performance (12,19,29,32). As a result, much effort has been spent by sports scientists and coaches in search of the optimal methods by which to train and improve power production and force development, particularly in the back squat exercise (2,9,10,16,25,34-36,42,43,45).

Elastic bands offer variable resistance throughout a range of motion (17), and their incorporation with exercise movements has long been used for rehabilitation purposes. More recently, however, elastic bands have found a niche in many strength programs because of the purported performance benefits (34,42). Elastic bands for rehabilitation are characterized by portability, light resistance, and versatility. In contrast, the elastic bands used in a strength training environment are thicker and have been used as a form of variable resistance training (VRT), which accommodates the strength curve of extension-type exercises. Additionally, elastic bands have been used in strength training as a means to create an overspeed eccentric phase, which has been shown to enhance the effects of the stretch-shortening cycle (SSC) (36). The SSC is a component of virtually all dynamic movements that involve a lengthening (eccentric) and shortening (concentric) of the muscle-tendon unit (i.e., series elastic component) during the reversal phase of the movement. Although the SSC and the associated mechanisms of greater force production have been described at length elsewhere (14,18,26,27,31,33,43,44), it can briefly be said that the increased concentric force produced by the SSC phenomenon is the result of a combination of neural reflexes and the ability to use stored elastic energy in the muscle-tendon unit. A major training benefit incurred by enhancing the SSC phenomenon is increased power production (28), which is linked to RFD and velocity of movement. The RFD on both sides of, and in close proximity to, the zero-velocity point (which occurs within the reversal [coupling] phase of the exercise) is of particular interest because of the implications of the SSC.

Many practitioners advocate the use of elastic bands in their strength programs. Although there is anecdotal evidence that supports the use of elastic bands over traditional resistance training (38-40), there is a paucity of research on the topic. The few studies that have sought to quantify the benefits of band training during the back squat, as they relate to force and power production, have yielded conflicting results and have each used different designs and methodologies (2,11,16,34,42). Limitations of these studies have been the metrics assessed, the instrumentation used to collect data, small sample sizes, and inconsistent protocols as they relate to type of exercise, load and apparatus used, and technique. For example, squatting-type movements performed on Smith machines and leg press machines constrain the movement to a single plane and do not represent the multidimensional movement of most sport activities (10). In addition, squat depth is rarely quantified, and differences in squat depth can create varying results. From the current literature, variations in range of motion, apparatus, and measurement techniques make it difficult to form an overall conclusion about elastic band training. Lastly, studies that involve multiple testing days rarely implement strategies to determine the subjects' general state on each day in terms of fatigue level, muscle soreness, neuromuscular status, etc.

The current study incorporated the free-weight barbell version of the squat exercise because it is frequently used as a fundamental training exercise across many sports. The equipment and instrumentation used for data collection ensured that extrapolation, estimation, and assumption of such critical components as force and velocity were kept to a minimum. The inclusion of the free-weight exercise and the instrumentation and methodology used for data collection are significant enhancements to this study. The use of 2 force plates and a 9-camera motion capture system allowed for independent force and displacement data as recommended by Hori et al. (21), and the free-weight back squat is an exercise that allows for free movement in space, which is reflective of most sport activities. The purpose of this study was to assess the following variables during the free-weight back squat exercise with and without the application of elastic bands: peak velocity in the eccentric and concentric phases (PV-E, PV-C), mean velocity in the eccentric and concentric phase (MV-E, MV-C), peak force (PF), peak power in the concentric phase (PP-C), and RFD values immediately before the zero-velocity point at the bottom of the movement (RFD A), immediately after the zero-velocity point (RFD B), and in the concentric phase (RFD C).

Methods

Experimental Approach to the Problem

This study was designed to determine whether a greater eccentric force that is applied with elastic bands translates into a faster and more powerful concentric phase in the barbell back squat exercise when compared to a condition in which no bands are used. It was hypothesized that bar velocity in the eccentric phase with bands would be greater than the nonband condition because of the increased acceleration (via increased force) provided by the elastic bands. It was further hypothesized that this increased velocity would translate into a faster and more forceful concentric phase because of the SSC phenomenon and yield increased values for all variables observed in this study: velocity (PV-E, PV-C, MV-E, MV-C), power (PP-C), force (PF), and RFD (RFD A, RFD B, RFD C).

Subjects came to the laboratory on 3 separate days. The first day (day 1) involved the screening and consent process, the collection of biometric data, and the estimation of each subject's 1 repetition maximum (1RM). Day 1 was performed at least 3 days before the first experimental condition (day 2). The following week, on days 2 and 3 (separated by 72 hours in a Monday-Thursday or Tuesday-Friday testing format), each subject performed 3 sets of 3 repetitions of the back squat with 5 minutes of rest between sets. The resistance on the bar was chosen to be 55% of the predicted 1RM. This percentage was chosen because it falls near the average percentage that has been reported in the literature to be most effective in eliciting maximum power production (5,9,24,36,45). For each condition, the subject performed the squat with the same constant weight on the bar (55% 1RM) but with additional force (20% of the 55% 1RM at standing position) provided by bands on 1 day. The 20% additional force from the bands was chosen because it fell within the range of values used in previous studies and represented a practical load for the bands to exert (11,16,42). The 2 conditions, no bands (NB) and with bands (WB), were randomized so that half of the subjects performed squats with bands on the first experimental day and without bands on the second experimental day, and vice versa for the other half of the subjects.

Subjects

Twenty-two healthy men (26.0 ± 4.4 years) who were experienced in weight training (mean experience = 10.4 ± 4.7 years), including the back squat exercise, were recruited for the study. Inclusion criteria were (a) at least 1 year of resistance training experience, (b) self-reported familiarity with performing the free-weight barbell back squat exercise, (c) male, and (d) 18-35 years of age. Exclusion criteria included (a) high blood pressure (resting systolic > 139 mm Hg or resting diastolic > 89 mm Hg) and (b) prior or current musculoskeletal injury that could be made worse by performing the back squat exercise (e.g., knee, ankle, hip, shoulder, low back). Two subjects did not complete the study because of injury; 1 subject sustained a rib injury during the preliminary testing phase, and the other injured his ankle in an unrelated activity. The biometric data and characteristics of the 20 subjects who completed the study are presented in Table 1. All subjects were informed of the experimental risks and signed an informed consent document before the investigation. The investigation was approved by the Institutional Review Board for the use of human subjects at the University of Minnesota.

Procedures

Preliminary Testing

After completing the screening and informed consent process, subjects were measured for biometric data. Height was measured to the nearest 0.1 cm with a wall-mounted stadiometer (Seca, Hamburg, Germany), and weight was recorded to the nearest 0.1 kg with a certified digital scale (Tanita BW-800A, Arlington Heights, IL, USA). Body composition was assessed via densitometry using the hydrostatic method. After the collection of biometric data, each subject's 1RM was determined. The subject warmed up for 5 minutes on a stationary, upright bicycle at a workload of approximately 80 W. After the general bike warm-up, the subject performed a specific warm-up that consisted of several sets that followed a trend of increasing load and decreasing repetitions. All squats performed in this study had trained spotters present and used a calibrated and certified competition power lifting set (bar, plates, and collars) in kilograms (Ivanko, Los Angeles, CA, USA). Squats were performed without the use of any type of supportive equipment (e.g., squat suits, knee wraps). Maximal back squat strength was estimated via a 4-6RM protocol in which the subjects gradually worked up to a weight that induced failure after 4, 5, or 6 complete unassisted repetitions. During all squats, subjects were instructed to descend to at least the point at which the tops of their thighs were parallel to the floor. Once the maximum weight for a 4, 5, or 6RM was established, maximum squat strength (1RM) was estimated using the %1RM-repetition relationship (4).

Testing Procedure

The experimental conditions occurred on 2 days: 1 in which squats were performed with bands (WB) and the other with no bands (NB). These experimental conditions were randomized and performed the week after the preliminary testing. All subjects chose either a Monday-Thursday or Tuesday-Friday testing format to ensure consistent and adequate recovery times. Subjects were instructed to refrain from heavy exercise the day before a testing trial. Subjects arrived at the laboratory each testing day and were weighed and performed the general warm-up on the bike as previously described in the preliminary testing section. After the general warm-up, subjects performed vertical jump (VJ) and hand dynamometry (HD) tests to ensure that their overall neuromuscular status was consistent (statistically similar, p ≥ 0.05) between the 2 testing days. Three maximal jumps were performed and recorded to the nearest 0.5 in. (1.27 cm) using a Vertec™ VJ testing device (Sports Imports Inc., Columbus, OH, USA), and the highest score was recorded. For the HD test, maximal isometric grip strength was measured with a handheld dynamometer (Baseline, Irvington, NY, USA) 3 times in each hand in an alternating format and recorded to the nearest 1.0 kg. The highest score for each hand was recorded and summed to yield the final recorded value. Subjects were also weighed at the beginning of each experimental day to ensure that body weight was not significantly different between the 2 conditions.

After the general warm-up and neuromuscular testing, subjects were fitted with 4 hemispherical reflective markers that would be used to quantify squat depth using a 3D motion capture system. Two markers were taped on each side of the body in a symmetrical fashion at the knee (the marker was placed laterally at the level of the joint space between the femur and tibia) and hip (greater trochanter). For the purpose of measuring bar velocity, a marker was also placed on the center of the barbell. All subjects performed the squats wearing spandex shorts to minimize excessive marker movement at the hip, and thigh angle was defined as the angle created between the vertical plane and the knee-hip vector, as shown in Figure 1. Markers were always placed by the same individual to ensure consistency of placement. Once the markers were securely placed in the correct positions the subject began their squat-specific warm-up. This warm-up followed a similar procedure as the one used for preliminary strength testing except the final weight was 55% 1RM as opposed to 85-90% 1RM. The warm-up protocol was matched exactly between the first and second experimental days. Next, the bar was loaded to the corresponding 55% 1RM resistance (rounded to the nearest 2.5 kg to accommodate the smallest weight plate denomination). During the NB condition, the bar was simply loaded to the 55% 1RM weight. During the WB condition, the appropriate band tension was determined and applied. The "mini" bands (Jump Stretch Inc., Youngstown, OH, USA) were attached on each side of the bar (in a symmetrical and equidistant fashion) and anchored with loading pins threaded through 50-kg plates that were laid flat. The loading pins were situated so that the bands were vertical during the squats. The upper end of each band was looped around the bar ( Figure 2). The number of times the band was looped around the bar was determined by how much tension was required for the individual. In the WB condition, the bands exerted maximal tension (20% of the 55% 1RM) in the fully erect starting (and finishing) position and zero tension (bands slack) in the bottom position to equalize the loads at the zero-velocity point of the reversal phase for each experimental condition. This method was used to equalize the weight in both conditions to accurately analyze the SSC and its effects. Looping the bands around the bar was the most effective method by which to achieve the 20% target. All subjects were within 1% of the 20% target (overall mean ± SD; 20.10 ± 0.46%). Determining the number of loops was a trial-and-error process that involved having the subject initially stand on the force plate with just the empty bar and then repeating the process 2 or 3 more times with varying numbers of loops. The band tension was simply calculated by taking the differences in recorded weights. The goals were to ensure that (a) the bands added the prescribed force in the upright position (starting and finishing points), and (b) the bands were slack at the bottom of the squat (transition from the eccentric to concentric phase) so as to equalize the loads at this position between experimental conditions. It should be noted that in 4 subjects, the band tension was slightly greater than zero at the bottom; this was because of either a greater tension requirement for strong subjects or very tall subjects with a greater range of motion.

Once the warm-up was completed (and band tension calculated for the WB condition), subjects were instructed to perform 3 sets of 3 repetitions of the squat with 5 minutes of rest between sets to allow for recovery of the phosphagen adenosine triphosphate (ATP) energy system (4). Sets of 3 repetitions were chosen because of the observation that power output decreases significantly after 3 repetitions in power exercises (6). Once given the signal, the subject placed the bar on his back and took 1 step backward and assumed a symmetrical stance (self-selected stance width) on the force plates. Each subject then began the set of 3 repetitions at his or herr own discretion. The 2 major instructions given to the subjects regarding the performance of the squat were to (a) descend to a depth at least equal to the tops of thighs being parallel to the floor and (b) descend and ascend as fast as possible (i.e., complete each repetition as quickly as possible).

Data Collection and Analysis

Biomechanical data were collected using a 9-camera motion capture system (SMART-e, BTS Bioengineering SPA, Milan, Italy) and 2 portable force platforms (Kistler, 9286AA, Winterthur, Switzerland), which provided a separate yet time-synchronized measurement of both displacement and force data. The cameras and force plates were controlled using the SMART software package (includes SMARTcapture, SMARTtracker, SMARTanalyzer, and SMARTviewer, version 1.10.346.0, BTS Bioengineering SPA). The 2 force platforms measured vertical ground reaction forces (GRFs) for each foot, which were later added to yield a net force in the vertical direction. Both force plates were zeroed before each set, and the sampling frequency was set at 960 Hz. Vertical displacement data were acquired via the infrared camera system and a reflective hemispherical marker taped to the center of the barbell. The sampling frequency of the cameras was 60 Hz. The camera and force plate system were calibrated before each of the testing days.

SMARTcapture was used for recording the data; the signals were collected via analog hubs and an Analog-to-Digital Converter (ADC) Peripheral Component Interconnect (PCI) card, both part of the SMART system. The displacement and force data were filtered in SMARTanalyzer using a moving average rectangular smoothing window with widths of 5 frames and 7 frames, respectively. Data were then analyzed to determine the dependent variables using SMARTanalyzer and MATLAB (Ver. R2006b, The Mathworks, Inc., 2006). All dependent variable values were calculated exclusively with SMARTanalyzer with the exception of RFD data, which required further processing in MATLAB.

Bar velocity was calculated using the vertical displacement and time data. The concentric and eccentric phases were defined as the time at which the velocity was positive (bar being raised) and negative (bar being lowered), respectively. This definition was held constant throughout all calculations. Force data used in the analysis were found by summing the 2 force platform vertical measurements, yielding a net force in the vertical direction. Peak force occurred at the transition between the eccentric and concentric phases (i.e., at the bottom of the exercise cycle where the bar transitions to the upward movement). Power was calculated from the product of the synchronized bar velocity and net (summed) force data. The peak power values were taken in the concentric phase and occurred in the latter half of the concentric movement.

Values for RFD were observed during 3 different time intervals along the force-time curve, which are displayed in Figure 3; RFD was found by differentiating the force-time curve. The mean RFD was calculated over each of the 3 time intervals to give an accurate representation of the slope within that time. Time intervals A and B represent the mean RFD 0.15 seconds on either side of the PF. Because the PF was always associated with the transition from eccentric to concentric, the mean RFD values represent the last 0.15 seconds of the eccentric phase, and the first 0.15 seconds of the concentric phase. The reason for looking at these values was to assess the effect of the SSC at the bottom of the exercise for each condition, NB and WB. If a steeper spike was present-representing rapid force development from the eccentric to concentric phase-the mean RFD values would be greater and vice versa. Note that in the concentric phase, the RFD in the first 0.15 seconds is negative; thus, a more negative value would represent a steeper (greater) slope ( Figure 3). The time duration of 0.15 seconds was chosen by carefully analyzing each subject's force-time curve about the zero-velocity point. The time interval of 0.15 seconds allowed, for all subjects, the greatest number of data points to be analyzed while staying within the unambiguous bell-shaped portion of the force-time curve. Time interval C represents the positive RFD values (from the local minimum to the local maximum) in the concentric phase leading up to the second peak in the force-time curve. This time interval is associated with the force production as subjects began to reach a more favorable biomechanical position.

For all dependent variables, the value for each set was found by taking the greatest value from the 3 repetitions. The 3 set values were then averaged to yield an overall value for each subject in each condition. The averages for each subject in each condition were then averaged to give a final value for both conditions. These final mean values for each condition were used for comparison of the NB and WB conditions. This method was chosen to best represent each of the conditions and exclude possible outlying values because of poor repetitions. An exception to this method was the calculation of the thigh angle. For this value, all 3 repetitions were taken into consideration to yield an overall average for each subject in each condition.

Statistical Analyses

Means and SD s were calculated for each dependent variable and each condition. Independent variables were defined as the percentage load (55% 1RM) being lifted and the percentage added (20% of the 55% 1RM) because of the elastic bands. The predetermined criterion for statistical significance was set at an alpha level of 0.05.

A paired sample t-test was conducted for each of the dependent variables to determine whether significant ( p ≤ 0.05) differences occurred between the NB and WB conditions. Means and SDs were also computed for biometric and neuromuscular status data. These data were compared using a paired sample t-test to ensure the subjects were not statistically different ( p ≥ 0.05) for each of the testing conditions. All of the hypotheses testing calculations were performed with SPSS statistical software for Windows (Version 14.0, SPSS Inc., Chicago, IL, USA).

A multiple variable Pearson correlation was performed to determine the test-retest reliability for the 3 sets performed in each condition for each dependent variable. Correlation coefficients were calculated and are summarized in Table 3. Correlation calculations were performed using Minitab (Version 15.1.1.0, Minitab Inc., State College, PA, USA).

Results

A summary of the means, SDs, and p values, can be seen in Table 2. Figures 4-12 graphically display the results for each dependent variable. The statistical analysis showed significant differences between the NB and WB conditions for 4 of the nine dependent variables observed: PV-C; PV-E; MV-C; and RFD C. In support of our hypothesis, PV-E and RFD C were significantly greater in the WB condition than in the NB condition ( p = 0.011, p = 0.028, respectively). In contrast to our hypothesis, however, PV-C and MV-C were significantly greater in the NB condition than in the WB condition ( p < 0.001, p = 0.002, respectively). The remaining dependent variables (MV-E, PF, PP, RFD A, RFD B) did not show significant differences ( p ≥ 0.05) ( Table 2). Correlation coefficients for the test-retest reliability of the 3 sets performed can be seen in Table 3. The average overall coefficients for the NB and WB conditions were 0.859 and 0.854, respectively.

No significant differences ( p ≥ 0.05) were found between each testing day for either the subject neuromuscular status (VJ, HD) or body weight data. The average differences between the testing conditions for each subject were: VJ: 1.97 ± 1.27 cm; HD: 2.95 ± 2.19 kg; weight: 0.73 ± 0.47 kg. In addition, there was no significant difference ( p ≥ 0.05) between the depths of the squat (indicated by the thigh angle measurement) for each testing condition: NB: 79.59° ± 8.42°; WB: 78.19° ± 9.57°.

Discussion

Anecdotal claims from strength coaches and other practitioners indicate that training with elastic bands in certain exercises is more effective at eliciting strength and power gains than traditional methods alone (38-40). However, the relatively small amount of previous research on the topic has yielded conflicting results. Ebben and Jensen (16) found no differences in GRFs between regular back squats and squats performed with bands, whereas Wallace et al. (42) showed that peak power and PF were greater when bands were incorporated compared to the constant load condition. The findings of the current study also yield conflicting results. In the present study, it was hypothesized that the use of bands creates an overspeed eccentric phase that elicits a greater response from the SSC and translates to improved power development, RFD, and velocity in the concentric phase. In general, the results of this study do not support our hypothesis and refute anecdotal claims. Only the peak velocity in the eccentric phase and RFD in the concentric phase were significantly greater in the squats performed with bands as compared to without bands. Additionally, the fact that mean and peak velocities in the concentric phase were greater without bands suggests that bands actually hinder concentric velocities in the squat.

In support of the hypothesis, peak velocity in the eccentric phase (PV-E) was significantly greater in the WB condition than the NB condition. This can be explained by the fact that the bands imparted a greater force to the bar and therefore caused a greater acceleration of the bar in the eccentric phase. This would be particularly evident in the beginning portion of the eccentric phase when the bands exerted the greatest tension. However, mean velocity in the eccentric phase (MV-E) was not significantly affected, which is in contrast to the hypothesis, and suggests that no overspeed eccentric phase occurred. One possible explanation for this seemingly contradictory finding is that there may be a more pronounced deceleration phase toward the end of the eccentric portion of the lift to counteract the greater peak velocity. It is possible that there is some protective mechanism that subconsciously controls the eccentric velocity and does not allow individuals to exceed a particular threshold regardless of the magnitude or type of load. Over many years some highly trained individuals develop an ability to alter this threshold and therefore have the ability to descend faster with greater or varying loads.

Both peak and mean velocities in the concentric phase (PV-C and MV-C, respectively) were significantly greater in the NB condition than in the WB condition; this finding, although significant, is in opposition to the hypothesis. A possible reason for this may be that peak velocities were found to occur at an approximate thigh angle of 50°, which represents a stage that the elastic bands were exerting additional force. This additional force (compared to the same point in the NB condition) likely had a deceleration effect that would have reduced both peak and mean velocities in the WB condition. These results do not support the idea that using elastic bands in the squat produces increased velocity in the concentric phase because of an exploitation of the SSC. Interestingly, if velocity is an important performance variable as some have suggested (23), these findings actually support the traditional mode of constant resistance.

Peak force was not significantly different between the 2 conditions and was always attained at the bottom position of the squat during the transition between the eccentric and concentric phases (i.e., coupling phase). This was also in contrast to the hypothesis and further suggests that there was no overspeed eccentric phase elicited by the incorporation of bands. Had an overspeed eccentric phase occurred, it would have likely been reflected by the PF at the reversal point. For example, if the overall eccentrics phase had been faster (i.e. greater MV-E), a greater deceleration would have been required to slow the bar to a stop and reverse the movement into the concentric phase. To generate a deceleration of a greater magnitude, a greater force would have been required, simply based on Newton's second law ( F = ma). Because no difference in PF was seen in the present study, it is possible to conclude that no overspeed eccentrics were observed in the WB condition.

No significant differences were observed in peak power between the 2 experimental conditions, which does not support the hypothesis. Peak power, as opposed to mean power, was measured because of its stronger correlation to performance (15). At the time of peak power in the concentric phase, which occurred near the time of peak velocity, it is important to note that the bands were engaged. Because power equals force times velocity, and the values of both experimental conditions were very close, it was inferred that at the time of peak power, there was relatively less force and greater velocity in the NB condition and greater force and relatively smaller velocity (because of the engaged bands) in the WB condition. These inferences, with respect to velocity, are in agreement with the results observed for PV-C and MV-C. A great deal of research has focused on the loads and training strategies necessary to optimize power output (5,9,12,13,15,21,22,24,33,36,41,42,45). The fact that no difference was detected in peak power between the 2 conditions does not support the premise that training with bands is more effective than using traditional modes for optimizing power output.

Rate of force development was examined at 3 separate time intervals, which is a unique aspect of this study. The first 2 intervals represent the time periods corresponding to 0.15 seconds immediately before (RFD A) and after (RFD B) the zero-velocity point (reversal point). These time intervals, A and B, best represent the SSC surrounding the reversal point for all subjects and allow for the maximum number of data points to be analyzed without going outside of the clearly defined bell-shaped portion of the force-time curve ( Figure 3). There was no difference in either RFD A or RFD B between the 2 conditions that is in opposition to the hypothesis. Because this is the point at which the loads were equal between the NB and WB conditions, significantly greater RFD values during the A and B time intervals would have been strong evidence in support of an overspeed eccentric phase and augmented SSC effect. RFD C was defined as the positive RFD in the concentric phase and corresponded to the time interval at which subjects were in a more biomechanically favorable position for force production. RFD C was found to be significantly greater when bands were incorporated; however, based on the current results, this finding cannot be attributed to an enhanced SSC and overspeed eccentrics. Rather, although the exact mechanism remains unclear, the current findings lend support to the notion that VRT in the form of elastic bands may be effective in increasing RFD in the concentric phase, and numerous authors have stated that RFD is particularly important because it relates to performance (1,3,20).

A differentiating and important aspect of the current study was the methodology by which data were collected and analyzed, which was largely because of the instrumentation used in this study. In particular, the advantages of the 9-camera motion capture system include independent and synchronized displacement and force data, purely vertical displacement data from a multidimensional movement (free weights), and quantitative depth measurement of the squat. In addition to the instrumentation used for the collection, the VJ and HD muscular/neuromuscular tests were unique to this study and ensured that subjects were at similar capability levels for each of the testing conditions.

Other studies have reported using only a single measurement source-either a force platform or a displacement measuring device-for calculating variables that require both displacement and force data, such as power ( P = F × V) (5,42). This method of collection has been criticized for the data manipulation required to reach such values (15,21). The use of either force or displacement data requires double integration or differentiation, respectively, to determine the power values, which can lead to less accurate results (15). The current study used the 9-camera motion capture system for displacement data, and 2 independent force plates (1 for each foot) for the collection of force data, thus following the recommended methodology (15,21).

Another advantage of the 9-camera motion capture system is that it can extract sole vertical displacement data from the 3-dimensional motion of a free-weight back squat. Commonly, studies use a single linear position transducer for collecting free-weight squat displacement data (5,44). This methodology has been subject to criticism, however, because it conjugates x-direction (anterior-posterior) and z-direction (lateral-medial) motion with the vertical direction motion (9). This can lead to less accurate displacement and velocity measures. Other studies have used Smith machines, which constrain the movement of the bar to the single vertical plane (10,30,36). This method has an obvious disadvantage in that it does not accurately represent the common free-weight squat used in training and does not mimic the multidimensional movement of sport.

In addition, the majority of studies that involve a squat exercise do not specify nor quantify the depth to which the subjects descend during the movement (5,9,42,45). The advantage of the 9-camera motion capture system was that it could quantify the depths of each subject using reflective markers on the hip and the knee. The results showed an average depth that was consistent between both conditions (NB: 79.59° ± 8.42°; WB: 78.19° ± 9.57°) and a very low average difference between the NB and WB conditions for each subject (3.33° ± 2.92°). These results suggest that the bands had a minimal effect on the range of motion of the exercise and that the depth between each condition was not a contributing factor for the observed differences in dependent variable values. Although every subject was instructed to go down to a depth such that the top of the thigh's were parallel to the floor-and thus the vector from the knee marker to the hip marker would be parallel to the floor-interestingly, our results show that on average the subjects did not reach 90°. This finding suggests that either (a) beginning to intermediate level individuals do not (or cannot), in general, descend to depths approximate to the thigh being parallel to the ground, or (b) people generally perceive they are descending to greater depths than they really are.

One unique aspect of this study was the use of neuromuscular testing to assess each subject's status. It was thought that any major differences in subjects' muscular fatigue levels or neuromuscular status from 1 testing day to the next would be manifested by differences in maximal vertical jumping or isometric HD. It was also assumed that the performance of the 2 tests before doing the squats would not significantly fatigue the subjects. A difference in performance on either of the 2 tests would have indicated reduced potential for an absolute maximal effort because of fatigue or other factor(s). The fact that there were no differences between the 2 testing days for either test indicates that the potential for a maximal effort was similar. The relationship between neuromuscular testing and performance is a potentially beneficial tool for researchers and practitioners alike; however, more study in this area is needed. If a strong correlation is indeed shown to exist between the performances of a VJ or HD test and potential for maximum performance, it would be invaluable to conduct these tests not only in research settings but also in the field. Training variables could then be manipulated daily and individually based on fatigue levels that may not be otherwise apparent or visible.

However, there were limitations to this study: The first was that the bands were never fully slacked at the bottom of the squat in 4 subjects. In addition, the bands did not slacken or tense up at the exact same relative point during the range of motion for any 2 subjects. The overall results of the study were likely not significantly altered because only 4 subjects did not experience a complete unloading of the bands and only minimal tension was present in these cases. This limitation was caused by using the same pair of bands for each subject and effectively shortening the band to increase tension. For example, the particularly strong subjects required a greater number of band loops around the bar (see Figure 2) to achieve the prescribed band tension in the upright position. Because the bands were shortened to such a degree for the stronger subjects, a complete relaxation of the bands was not achieved in the bottom position. Using varying thicknesses of elastic bands (based on strength levels) would have solved the problem of the "slackness" at the bottom of the squats but would have produced a new quandary in that the rate of tension development would have been different between differing thicknesses of bands. Custom-made bands with lengths and thicknesses based on individuals' strength levels and dimensions is 1 suggested way to improve upon this limitation.

Another limitation of the study was the heterogeneity of the subjects. The majority of subjects were classified as intermediate in terms of ability and experience. However, a few subjects were advanced as evidenced by their experience in competitive power lifting and Olympic weightlifting. It is possible that the results may have been different if all subjects fell within a particular experience and ability level. This classification can be difficult to quantify but is a consideration nonetheless, especially in light of the fact that much of the anecdotal evidence that supports the use of elastic bands has come from elite-level strength athletes (38-40). Finally, although it is clear that most subjects did not achieve the desired squat depth, this is not considered a limitation because each subject went down to the same depth in both conditions. The 1 caveat to this is the relationship of the SSC to squat depth. Although it is a viable conclusion that a deeper squat may have different implications related to the SSC phenomenon, this remains to be fully elucidated.

In conclusion, performing free-weight back squats with a load of 55% 1RM plus an additional force equal to 20% of the 55% 1RM load (provided by elastic bands) does not appear to elicit the favorable acute performance changes that have been reported anecdotally. The loads and elastic band tensions used in this study do not appear to induce an overspeed eccentric phase, and the SSC phenomenon does not appear to be significantly altered. The salient findings indicate that although there was an increase in RFD in the concentric phase and an increase in peak eccentric velocity using elastic bands, the mean and peak concentric velocities were greater when squats were performed without bands. The conflicting results of this study highlight the need for more research on the topic of VRT in general and elastic bands specifically. In particular, greater band resistance is an area that should be explored across all experience and ability levels.

Practical Applications

This study calls into question the claims made about the elastic band method of VRT. The results suggest that training with moderate loads combined with moderate band tension does not confer any additional overall benefits to those of traditional techniques. However, this study does provide evidence that RFD may be positively affected by training with bands; for individuals interested in this specific parameter, it may be advantageous to consider incorporating this easily implemented training variation. Additionally, using elastic bands with compound movements like the barbell back squat and bench press may allow for more ballistic-type training typically relegated to plyometrics (8,37). This could then allow for the intention to produce a maximal velocity through the entire concentric range of motion that some believe to be more important than the actual movement velocity (7). Conversely, because the findings of this study indicate that concentric velocity is negatively influenced by elastic band training, practitioners interested in enhancing velocity-related components should be cautious of band training.

Acknowledgments

This study was conducted by the University of Minnesota Sports Biomechanics Special Interest Group and made possible through funding from the Institute for Engineering in Medicine at the University of Minnesota, Twin Cities.

References

1. Aaraard, P, Simonsen, EB, Anderson, JL, Magnusson, P, and Dyhre-Poulsen, P. Increased rate of force development and neural drive of human skeletal muscle following resistance training. J Appl Physiol 93: 1318-1326, 2002.

3. Anderson, LL and Aagaard, P. Influence of maximal muscle strength and intrinsic muscle contractile properties on contractile rate of force development. Eur J Appl Physiol 96: 46-52, 2006.

20. Holterman, A, Roeleveld, K, Vereijken, B, and Ettema, G. The effect of rate of force development on maximal force production: Acute and training-related aspects. Eur J Appl Physiol 99: 605-613, 2007.

27. Komi, PV. The stretch-shortening cycle and human power output. In: Human Muscle Power. Jones, NL, McCartney, N, and McComas, AJ, eds. Champaign, IL: Human Kinetics, 1986. pp. 27-39.

34. Newton, RU, Robertson, M, Duncan, E, Hasson, C, Cecil, J, Gerber, A, Hill, J, and Schwier, L. Heavy elastic bands alter force, velocity and power output during back squat lift. NSCA Conference, Las Vegas, July, 2002.

Keywords:
rate of force development; variable resistance training; stretch-shortening cycle

© 2010 National Strength and Conditioning Association

Article Keywords

Keyword Highlighting
Highlight selected keywords in the article text.

# data[].attributes.attachment_link.title
Acute Effects of Elastic Bands During the Free-weight... : The Journal of Strength & Conditioning Research

# data[].attributes.attachment_link.description
een reported to be effective in increasing performance-related parameters such as power, rate of force development (RFD), and velocity. The purpose of this study was to assess the following measures during the free-weight back squat exercise with and without elastic bands: peak and mean velocity in the eccentric and concentric phases (PV-E, PV-C, MV-E, MV-C), peak force (PF), peak power in the concentric phase, and RFD immediately before and after the zero-velocity point and in the concentric phase (RFDC).

# data[].attributes.body
Program details.
Mix of Broz and Westside.

# data[].attributes.attachment_link.title
Cory Gregory's Squat Every Day | Bodybuilding.com

# data[].attributes.attachment_link.description
Squat Every Day will challenge you, test your resolve, and reveal your character. But if you have what it takes to squat daily, you'll gain strength, build muscle, and become a better lifter. This is for the hardcore.

# data[].attributes.body
Cory Gregory discusses the benefits of adding lunges to workouts to supplement leg development.

# data[].attributes.attachment_link.description
Member Access Only Sign-up Now Username Password Remember Me Forgot Password

# data[].attributes.body
"I plan to study the impact of squatting everyday because I want to find out its overall effect to show growth in performance so that I may better understand how to maximize student performance."

Reasoning:
I am considering student performance in weight training and conditioning as my action research project.  The focus of our weight training class is often on activity rather than achievement.  I am looking into researching a new way to structure the class in order to increase student performance and growth for all students in the class.

# data[].attributes.body
1.  What impact will squatting everyday have on the body?
2.  What impact will squatting everyday have on overall performance?
3.  What impact will beginning the workout with squats have on the mindset and body for the remainder of the workout?
4.  What impact will adding multiple squat variations have on overall performance?

# data[].attributes.body
Origins.
Increases flexibility.
Promotes core strength.
Reduced chance of injury.
Releases more growth hormone and testosterone.
Common myths.

# data[].attributes.attachment_link.readable_text
Click Here To Calculate Your Current Squat Max

If you are going to participate in resistance training...why would you choose the path of least resistance?

There's an old saying that goes, "If it's important, do it every day." That's the premise behind Squat Every Day by Cory Gregory. This program will have you step into the squat rack daily, load-up the bar and push some iron. You will not only challenge yourself physically, you will challenge yourself mentally. Test your limits. Your resolve. Cory Gregory believes that if you can stick with the program for 30 daysâ€"or even 365â€"you won't just build bigger legs. You'll become a better lifter, increase your overall strength, and grow like crazy.

Cory Gregory from MusclePharm is at it again. This time he is bringing us a program that challenges us to get under the bar every day and SQUAT! The Cory Gregory Squat Everyday program is totally legit.The Squat Everyday trainer is a 30-day program released on bodybuilding.com in April of 2015. I have been squatting every day since March 26, 2015 and also been participating in the #lungeuniversity (1/4 mile of walking lunges per day) and I have to say the legs are feeling stout. Welcome to the squat everyday musclepharm program.

Right now the biggest challenge when doing the squat everyday cory gregory program is mainly mental. It takes quite a bit of mental toughness to not only workout everyday, but to get under the bar and actually SQUAT some heavy weight. My legs were really sore for the first week, but began to taper off and now they don't really get sore at all. #squateveryday #lungeuniversity

If you commit to Squat Every Day with MusclePharm's president, you'll master 11 different squat variations. You'll increase weight daily to ensure consistent growth. You'll train other body parts after squatting so you can build size everywhere you want it, and you'll do it all in 60-75 minutes per day.

You don't need to do all 11 variations as John Broz (the guy who inspired Cory to come up with this program) says he only has his athletes do traditional front and back squats. Personally I am using four variations which include front squats, back squats, and pause squats for those two variations. As of now it is working well.

One of the main benefits of squatting everyday is the release of all of that natural growth hormone. It is widely accepted that the big lifts (squats and deadlifts) make your body release growth hormone, so by squatting everyday, this release is amplified and your entire body should benefit from it (not just your legs), which means all of your other lifts should go up simply because your entire body is becoming stronger.

One of the infamous quotes floating around the internet about squatting everyday is from the man himself, Mr. John Broz (of Average Broz Gym). Cory Gregory actually learned about this method from John, but here is what John says about squatting every day:

If your family was captured and you were told you needed to put 100 pounds onto your max squat within two months or your family would be executed, would you squat once per week? Something tells me that you'd start squatting every day. Other countries have this mindset. America does not.

John Broz

This actually makes perfect sense to me. If I needed to run a sub 5:00 mile I would run every day. So why not squat? Why do we only do what we think we should or what other people say we should do. Why do we worry about overtraining or CNS fatigue when we're probably not even close to ever touching those two thresholds? Get under the bar and squat everyday!
What if I'm too sore to squat everyday?
How you feel is a lie; that phrase is the Broz mantra. Your body will lie to you. Mr Broz can cite countless examples of athletes setting PR's on days they didn't even want to train, as well as days where the athlete felt like a million bucks but didn't fare so well in the gym. I personally have felt like shit and then went ahead and put up a new PR and when I'm done I remember thinking "dang, and I didn't want to even lift today".

According to an interview with Broz, he explained that the previous week his wrist was so sore that he could barely warm up with the bar during split jerks, but he pushed through it, eventually felt warmed up, and ended up jerking 405 lbs. The following day his wrist pain had vanished.

He describes this phenomenon as "floating pain" your body has to hurt somewhere. It will simply migrate from one place to the next while you sleep, and when you awaken you'll discover where it landed. Personally I can relate to this. As a 34 year old man, I'll wake up and something different always hurts even if I don't recall hurting it the day before. Warm-up and work through it.
There's no Such Thing as Overtraining
According to Broz, there is no such thing as overtraining - let's take a look at an excerpt of his beliefs:

If you got a job as a garbage man and had to pick up heavy cans all day long, the first day would probably be very difficult, possibly almost impossible for some to complete. So what do you do, take three days off and possibly lose your job?

No, you'd take your sore, beaten self to work the next day. You'd mope around and be fatigued, much less energetic than the previous day, but you'd make yourself get through it. Then you'd get home, soak in the tub, take aspirin, etc. The next day would be even worse.

But eventually you'd be running down the street tossing cans around and joking with your coworkers. How did this happen? You forced your body to adapt to the job at hand! If you can't' squat and lift heavy every day you're not overtrained, you're undertrained! Could a random person off the street come to the gym with you and do your exact workout? Probably not, because they're undertrained. Same goes with most lifters when compared to elite athletes.

John Broz 2002

The Squat Everyday Program from MusclePharm
In order to help us squat everyday effectively, Cory Gregory has come up with a 30-day squat everyday trainer that is available on bodybuilding.com. The program is essentially a bodybuilding split with the leg day removed since you will be squatting everyday anyways. Each workout will begin with 20-30 minutes of squats followed by an upper body routine. Most people *try* to squat once per week with an emphasis on "try". According to the MusclePharmPres:

And by "try," I mean I see guys squatting a quarter of the way down, skipping sets, and doing more talking than actual work. I built this trainer on the premise that, every single day, you're going to shut up and you're going to squat.

That's it, shut-up and squat. Move some iron and get huge. The Squat Everyday 30-day trainer from MusclePharm split looks like this:

As you can see, we don't have "leg day". It's LEG WEEK - No days off, no complaining.
Nutrition Guidelines for Cory Gregory's Squat Everyday Trainer
The Squat Everyday trainer comes with two different nutrition plans that you can follow: The Fat Loss Plan and the Weight-Gain Plan. Both of these nutrition plans are very similar, but the weight gain plan just contains a few more calories and contains two servings of carbs (as brown rice and sweet potato). The two plans really only vary by a few hundred calories.

You can read the full nutrition plan for the squat everyday trainer by MusclePharm here:
http://www.bodybuilding.com/fun/squat-every-day-nutrition-and-supplementation-overview.html
Supplementation Guidelines for MusclePharm Squat Everyday Trainer
If you are going to follow the Squat Everyday trainer soup to nuts, you will be taking several different MusclePharm supplements including their new Hardcore line. The supplements you'll find on the Squat Everyday trainer are:

MusclePharm Wreckage

MusclePharm Gainz

MusclePharm Whey Diesel

MusclePharm Combat Crunch Bars

MusclePharm Coco Protein Drink

That is quite a bit of supplementation, but as we all know, MusclePharm products are legit. If you don't have the bankroll to purchase the entire stack plus the bars and Coco protein drink, you should as always, start with the protein, then pre-workout and move-on from there.
THE BENEFITS OF SQUATTING EVERYDAY
1. Release of Growth Hormones and Testosterone
Total body exercises have been proven to stimulate the production of muscle-building hormones like Testosterone and growth hormone. Squatting involves almost every muscle in the body and thus gives you the most bang for your buck as far as benefits to your body as a whole. Not only will you be building tree trunks, the rest of your body will become stronger and primed for muscle growth.
2. Enhanced Core Strength
Squatting takes tremendous core strength - your core has to be stout in order to maintain that heavy load and keep an upright posture. Squats can also help you maintain those sixpack abs - espcially if you are doing front squats.
3. Increased Flexibility
Doing heavy, deep squats can drastically improve your flflexibilityhroughout your entire hip complex. This means less lower back pain and an easier time performing daily activities.
4. Reduce your chance of injury
As with all body parts, if they are strong and surrounded by muscle, you reduce the chance of injury due to strong stabilizer muscles. Strong, stout legs will help prevent knee injuries and keep the rest of your lower body less injury prone.
5. Improve Your Upper Body Lifts
If you want to bench press more, squat. If you want to curl more, squat. Having a solid base will carry-over to your other exercises and make you stronger and move more weight just by having a strong set of tree trunks to stand on (not to mention all the natural growth hormones you'll be secreting).
Roots of Squatting Everyday - Bulgarian Weightlifting & Ivan Abadjiev
Squatting everyday and even maxing out on squats every day is not a new idea. Sure it may just be spreading to the masses, however it roots can be traced back to Bulgarian weightlifting - namely head coach Ivan Abadjiev. However, most of the bulgarian weightlifting methodology that we currently know about came from Mr. John Broz who, for three years, lived with Antonio Krastev, a Bulgarian superheavyweight. While living with Krastev, he revealed to Broz the legendary Bulgarian weightlifting system.
What Is The Bulgarian Squat Methodology?
To put it simply, the Bulgarian method of training is a high intensity, high frequency methodology that was used by the Bulgarians when they were dominant in the sport under coach Ivan Abadjiev. This methodology, like we stated, has been recently popularized in the US by John Broz.
Common Myths about Squatting Everyday and The Bulgarian Method 1. Squatting everyday will ultimately lead to injury
It is a common fear that you will destory your tendons and knees by squatting heavy every day, however, this could not be further from the truth. Research has shown that the size and strength of the tendons will increase with repeated loading.

As long as your form and mechanics are proper, your risk of injury are low. We're also talking about technical maxes and NOT true maxes. You should have a heavy weight that you can squat with perfect form and without mental arousal.
2. Squatting everyday will lead to overtraining.
It is also a common belief that squatting everyday will lead to overtraining. Most of us average gym-goers have never even experienced anything remotely close to overtraining. Sure you may be sore for the first few days or weeks, but your body will adapt. Don't confuse soreness and aches and pains with over training - they are not the same.
3. You won't be able to gain muscle
Squatting every day goes completely against traditional bodybuilding wisdom of working a body part and giving it a minimum of 72 hours rest. However, with the Bulgarian system, we are not pushing our self to complete exhaustion with speeds up recovery time and allows us to stress our muscles more frequently which elicits more growth cycles.

http://www.bodybuilding.com/fun/squat-every-day-the-history-of-the-squat.html
http://www.bodybuilding.com/store/mp-hardcore-ambassador-search.html
This Post Is Tagged For:
squat everyday results
squat everyday program
heavy squats every day
is it ok to squat everyday
john broz squat
broz powerlifting method
can you squat everyday
squats every night
squat everyday cory gregory
squat everyday musclepharm program

# data[].attributes.attachment_link.title
Squat Everyday with Cory Gregory from MusclePharm

# data[].attributes.attachment_link.description
(Please visit the site to view this video) Click Here To Calculate Your Current Squat Max If you are going to participate in resistance training...why would you choose the path of least resistance? There's an old saying that goes, "If it&#3...

# data[].attributes.body
You show me a good study, and I will show you a guy who can squat more than you.

# data[].attributes.attachment_link.readable_text
Have you ever tried to squat every day?
Not air squats every day...

I'm talking heavy, barbell-on-your-back, squats every day.

This type of training is REALLY hot right now...again.

Yes, I said again.

Is a squat every day program new?

Not exactly.

I've noticed this method of training gains popularity in waves.

So let's talk squatting every day!

Close to five years ago (late 2010), I squatted every day for months, and enjoyed it.

Then, I brought a mini-version of "squat every day" to End of Three Fit about 2-3 years ago (and we will do it again).

It's a good push.

I've recently gotten a good amount of emails asking me about squat every day programs and I'm always happy to give my two cents on things I've tried, or know about.

For the most part, everyone's main concern...
SHOULD you squat every day??
Today, we are going to learn how to break down squat every day programs and get to the ultimate answer of:

Should YOU, like as in YOU reading this, squat every day?

But first, let's look at where squatting every day came from.

Squat Every Day History

Some say squatting every day, or rather, training every day goes back to the 1940's...

If you do the research, you'll find links to the Bulgarian Method and successful Olympic athletes who have adopted similar training ideas.

But I won't bore you with too much history or theory...

As far as I am concerned, John Broz is the man behind squatting every day and believes everyone can and should train every day.

He starts lifters off with daily heavy squatting, and produces phenomenal results.
Most know John Broz when they hear this quote:
"If your family was captured and you were told you needed to put 100 pounds onto your max squat within two months or your family would be executed, would you squat once per week? Something tells me that you'd start squatting every day. Other countries have this mindset. America does not."

While John has been a proponent of this method for a long time it didn't start to become popular until 2010-2011.

In 2010, Dave Lipson (for those who don't know, Camille LeBlanc 's Husband) started a year's challenge dedicated to Amanda Miller for skin cancer awareness.

He completed 365 days of squatting from 2010-2011 and his goal was to have AT LEAST 450 lbs on the bar every day.

Yes. 450 lb on the bar EVERY DAY!

I took on Dave's challenge in late 2010, and experienced my first bout of squatting every day.

I did it for several months, but I didn't put 450lb on the bar every day 🙂

But I did see results.

In 2011, Bret Contreras wrote a good article called " Max Out on Squats Every Day" which went semi-viral and Jim Wendler (renowned powerlifter) chimed in on the conversation.

In 2013, Matt Perryman released the book Squat Every day, chronicling his experience squatting every day which he picked up from watching and reading the training of John Broz.

Fast forward to now, and Cory Gregory broke the internet with his "Squat Every Day" program.

Cory says he created the program due to bombing out in a powerlifting meet in early 2014 and started researching and stumbled on...

None other than, John Broz.

Hey, full circle!

But how'd he break the internet?

Cory is the Founder of Muscle Pharm (a massive supplement company), he has a HUGE social following, a great relationship with one of the most trafficked websites in the WORLD (bodybuilding.com) and he did a great episode with the guys at Barbell Shrugged talking about this method.

That combination took squat every day from a "crazy training method" to a common everyday program.

In fact, you may be reading this because of his influence.

So, that's the history of Squat Every Day programs in the last decade or so.

Now, should you squat every day??

Should you squat every day (math time)?

I'm going to preface everything I'm about to say with...

Nothing pisses me off more than a coach or athlete with an opinion and no experience.

We can talk energy systems and textbooks until you are blue in the face, but without application it's useless.

You show me a study and I'll show you a guy who squats more than you.

Anyway...

I'm about to geek out here with some math to help you analyze a program, but I ALSO have squatted every day for months and know what it's like.

And don't worry, I'll keep the math light.
I'm combining my experience and knowledge to give you an opinion, or a starting point.
Analyzing a squat every day program is pretty easy, if you do it using Hristo Hristov: How to Design Strength Training Programs using Prilepin's Table, 2005.

Prilepin's Table, in short, depicts the optimum number and range of reps given a certain percentage to increase strength.

Prilepin's Table has its faults, and that is where Mr. Hristov comes in with his INOL (Intensity and Number Of Lifts) calculation.
Anyway, let's get straight to the math...

All we are doing is finding out how many total reps you are doing at a given intensity.

Whether that is 5 sets of 3 reps at 80% or...

3 sets: 5 reps @ 75%, 3 reps @85% and 1 rep @ 95%...

Or ANY combination you can think of.

Take your workout and find total reps at each given intensity and run it through this formula:

Here are two "Demos"

Now, you have a number designated to your workout, and remember this is for a SINGLE exercise; i.e. squat, deadlift, etc.
You take that number and compare it to these two charts:
This chart, we don't care about as much, but I'll explain that in a minute (still good to know)...

This is the chart we care more about...

Do the math for YOUR workout and find out where you are.

From the example above, you see they are .75 INOL and .6 INOL which fits in the "Doable and Optimal".

So what does your workout look like? Where does it fit?

If you are somewhere CLOSE (not exact) to these guidelines you are on the right track to a good squat every day program.

Furthermore, it really helps you set structure to a program which does not give you percentages.

Three Caveats to Doing the Math...

1.) Single Workout vs. Weekly Total. If you want to do a squat everyday program worry more about your "Single Workout INOL of a Single Exercise" from the picture above. If you are squatting every day you are already challenging conventional wisdom, so you will most likely blow the "Weekly INOL" out of the water.

2.) This is a guideline, not science. Don't get TOO hung up on the numbers here. This is a guideline to help you gauge what is "typical" and what will keep you training optimally. I've done programs which have had too much and too little INOL, but they were effective. The key here is longevity - What is sustainable, for YOU? What's YOUR starting point? What can YOU handle?

3.) DO SOMETHING. Don't hide behind math, but let it guide you. The real way to learn is through application and doing. Putting a little brain power behind a barbell can keep you safe - but still DO!!

So should you squat every day?

In my experience, it will yield results.

Lower volume at higher intensities is sustainable, but BORING.
But why not give it a try?
You may just perfect your squat and learn something new. Hey, no one said you have to do it for the rest of time. Give it a four week cycle.
Some freakishly strong people squat everyday, and some of the strongest men in the world don't...
It has to fit with their goals and their training.

So now, over to you...

Tinker. Play. Experiment. Learn. Have fun.

I'll leave you with a recent quote from my friend Nate Miyaki:

1. Knowledge acquisition without application is meaningless.

2. Education without an equal amount of execution, and subsequent experience, is useless.

3. Statistical significance in studies give you a good starting point, but only really matters if it makes a real world difference for you.

So will you squat every day?

-Jerred
photo credit: Enrico Fermi (1901-1954) via photopin (license)

# data[].attributes.attachment_link.description
Have you ever tried to squat every day? Not air squats every day... I'm talking heavy, barbell-on-your-back, squats every day. This type of training is REALLY hot right now...again. Yes, I said again. Is a squat every day program new? Not exactly. I've noticed this method of training gains popularity in waves.

# data[].attributes.headline
1) John Broz's "Max Out on Squats Everyday"

# data[].attributes.subject
1) John Broz's "Max Out on Squats Everyday"

# data[].attributes.body
Floating pain.
Your body lies to you.

# data[].attributes.attachment_link.description
A closer look at the Broz Olympic Method. Check it out.