# data[].attributes.body
Athletes being able to record their training and then compared analyse and breakdown the specific components of the lift
This type of video modelling increased accuracy of the skill acquisition of the steps of performing an Olympic lift

# data[].attributes.attachment_link.title
The Effects of Expert Video Modeling, Video Self- Monitoring, and Video Feedback on Improving Olympic Weightlifting Form - ProQuest

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This is a short preview of the document. Your library or institution may give you access to the complete full text for this document in ProQuest.

# data[].attributes.body
Using video footage to transfer skill acquisition to improve Olympic lifting technique
Effective for athletes to pick up technique
But how can this transfer to successful use of the acquired skill acquisition in competition

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Degree Granting Department

Child and Family Studies

Major Professor

Kimberly Crosland

Co-Major Professor

Raymond Miltenberger

Keywords

Behavioral Coaching, Skill Acquisition, Sport

Abstract

Behavioral coaching procedures have been evaluated and enhanced over the years to find the most effective interventions for athletic performance in a variety of sports settings. Different types of feedback have been evaluated for effectiveness in teaching and improving skills. The purpose of this study was to examine the effects of video modeling and video feedback to improve technique for three novice individuals in a fitness program incorporating Olympic weightlifting. Two weightlifting events, the clean and jerk and snatch, were targeted for intervention. Each lift was broken down into a task analysis, and trainers used the task analysis to score each lift. Video modeling and video feedback was effective in improving all three participant's lifts from baseline. Annie's lifts improved from 37% in baseline to 79% in intervention for the clean and jerk, and 24% to 75% for the snatch. Rich's lifts improved from 79% in baseline to 95% following intervention for clean and jerk, and 58% to 89% for the snatch. Fran improved from 60% to 87% on the clean and jerk, and from 51% to 84% on the snatch.

Scholar Commons Citation

Mulqueen, Danah, "Using Video Modeling and Video Feedback to Improve Olympic Weightlifting Technique" (2014). Graduate Theses and Dissertations.
https://scholarcommons.usf.edu/etd/5280

# data[].attributes.attachment_link.title
Using Video Modeling and Video Feedback to Improve Olympic Weightlifting Technique

# data[].attributes.attachment_link.description
Behavioral coaching procedures have been evaluated and enhanced over the years to find the most effective interventions for athletic performance in a variety of sports settings. Different types of feedback have been evaluated for effectiveness in teaching and improving skills.

# data[].attributes.body
Athletes using Visual aids to Learn technique
Video aids resulted in Athletes having better Power Clean results
Why does the use of video aid in a person learning skill acquisition faster
Focused on action observation (AO) facilitated learning on olympic lifting
AO was effective on improved technique (kinematics) which then led to an increase in strength (kinetics)
AO along with verbal cues before each set resulted in improve skill acquisition thus better improvement in results

# data[].attributes.attachment_link.readable_text
Sakadjian, Alex 1,2; Panchuk, Derek 1,3; Pearce, Alan J. ⁴

doi: 10.1519/JSC.0000000000000290

Sakadjian, A, Panchuk, D, and Pearce, AJ. Kinematic and kinetic improvements associated with action observation facilitated learning of the power clean in Australian footballers. J Strength Cond Res 28(6): 1613-1625, 2014-This study investigated the effectiveness of action observation (AO) on facilitating learning of the power clean technique (kinematics) compared with traditional strength coaching methods and whether improvements in performance (kinetics) were associated with an improvement in lifting technique. Fifteen subjects (age, 20.9 ± 2.3 years) with no experience in performing the power clean exercise attended 12 training and testing sessions over a 4-week period. Subjects were assigned to 2 matched groups, based on preintervention power clean performance and performed 3 sets of 5 repetitions of the power clean exercise at each training session. Subjects in the traditional coaching group (TC; n = 7) received the standard coaching feedback (verbal cues and physical practice), whereas subjects in the AO group ( n = 8) received similar verbal coaching cues and physical practice but also observed a video of a skilled model before performing each set. Kinematic data were collected from video recordings of subjects who were fitted with joint center markings during testing, whereas kinetic data were collected from a weightlifting analyzer attached to the barbell. Subjects were tested before intervention, at the end of weeks 2 and 3, and at after intervention at the end of week 4. Faster improvements (3%) were observed in power clean technique with AO-facilitated learning in the first week and performance improvements (mean peak power of the subject's 15 repetitions) over time were significant ( p < 0.001). In addition, performance improvement was significantly associated ( R ² = 0.215) with technique improvements. In conclusion, AO combined with verbal coaching and physical practice of the power clean exercise resulted in significantly faster technique improvements and improvement in performance compared with traditional coaching methods.

¹ College of Sport and Exercise Science, Victoria University, Melbourne, Australia;

² Melbourne Football Club, Melbourne, Australia;

³ Institute of Sport, Exercise, and Active Living, Victoria University, Melbourne, Australia; and

⁴ Cognitive and Exercise Neuroscience Unit, Center for Mental Health and Wellbeing, School of Psychology, Deakin University, Melbourne, Australia

Address correspondence to Alex Sakadjian, alex.sakadjian@live.vu.edu.au.

Introduction

Commonly referred to as demonstration, observational learning, or modeling (16), action observation (AO) can be defined as the interaction between a model and an observer. The actions of a model are viewed, causing adaptations of the observer's behaviors to match the outcomes and processes of the events demonstrated by the model (16,17,21,37). Horn and Williams (17) propose that for effective skill acquisition to be achieved, the transfer of information from instructor to learner is critical. In skill acquisition, the most common mode of information transfer is demonstration, from which the general movement patterns of the skill are observed by the learner (21,38). Action observation has been used as an effective method of communicating this information from instructor to learner, especially to novice learners (21).

Most AO-related studies have focused on fine, simple, or sport-specific skills and investigations have provided support to using AO for improving motor skills in both elite (5) and novice (2) level athletes. Buccino et al. (7) who investigated musically naive subjects observing an expert model playing guitar chords, demonstrated that through the use of AO, novel motor patterns can be developed. Similarly, Porro et al. (27) demonstrated that force production was increased after an AO intervention despite no physical training of the muscle tested. The investigation by Porro et al. (27) was one of the few studies found in the literature that investigated and reported changes to kinetic variables as a result of an AO intervention. The study was well controlled, and the improved muscle force results can be strongly attributed to the AO intervention; however, the muscle and motor skill that was investigated lacked specificity to athletic- or sport-related motor skills and muscles. The benefits of AO have also been used to investigate sport-specific skill acquisition. Weeks and Anderson (36) reported that improvements in the acquisition and retention of an overhead volleyball serve after exposure to video footage of a model performing the same skill with ideal form. The subjects in the study had either never performed the skill before or had not practiced the skill in the previous 3 years, which provides evidence of the benefits of AO in learning a skill and then retaining the learned skill for novice or detrained individuals. Baudry et al. (5) also investigated AO-facilitated learning of a sports skill, reporting greater improvements in gymnastic pommel horse technique for the group that received video modeling and feedback than the control group who did not.

The evidence discussed above demonstrates the beneficial impact that AO can have on learning a new motor skill and the subsequent improvements in performance of that motor skill. However, it is apparent that the benefits of using the AO concept have received limited research in a resistance training (RT) environment that is specific to sport performance, despite the obvious requirements for athletes to learn proper lifting techniques to improve strength and power qualities. Strength and conditioning (S&C) is a vital aspect of athletic preparation, especially at the elite levels of competition. The professional standards and guidelines of the National Strength and Conditioning Association (26) has made recommendations on athlete:S&C coach ratios and presented data across various sports athlete:S&C coach ratios; which vary between 3 and 14.8 athletes to 1 coach. The recommendations and guidelines do, however, suggest increased supervision for novice athletes, or athletes who have no experience in technical lifts, such as the power clean. Anecdotal evidence has suggested that in club-based sports systems, where the opportunities to fund S&C coaches is limited, working with large athlete:S&C coach ratios (i.e., 1:25) is not uncommon, making teaching and appropriate supervision of the technical aspects of RT exercises challenging. Taking the time to provide athletes proper technique coaching has, at times, been considered inefficient use of time for S&C staff (who need to supervise a number of athletes concurrently) and has provided a rationale for S&C coaches to question the prescription of exercises such as the power clean from the athletic conditioning program altogether, replacing them with simpler (e.g., squat jump) exercises. With the positive effects of AO-facilitated learning reported in skill acquisition literature, the application of AO theory to S&C practices of athletes could potentially assist S&C coaches in facilitating the learning of athletes in novel and technical exercises.

In terms of AO effects related to RT, Ram et al. (28) found that technique was improved for novice learners in groups that were exposed to observing a model with ideal form for both a barbell squat exercise and a balancing skill while also reporting an improvement in movement outcome for the barbell squat task. McCullagh and Meyer (25) also used a barbell squat exercise with a cohort that had never performed free weight squats previously; they reported that the observation of either skilled or novice models resulted in improved learning of the squat exercise with marginally greater improvement in form for the group that observed skilled models. Rucci and Tomporowski (30) investigated the effect of 3 different types of augmented feedback (video-only, verbal-only, and video-verbal) on hang power clean technique. The video-only and video-verbal feedback groups watched a video of themselves after performing each set of the exercise, therefore a self-model design AO intervention. Results demonstrated an improvement in hang power clean technique for both verbal-only feedback and video-verbal feedback groups, whereas the video-only group failed to show improvement in technique. Perhaps the RT study most similar to this study was performed by Winchester et al. (39) who investigated changes in bar-path kinematics specific to power clean technique while also investigating whether changes were also seen in kinetic variables after 4 weeks of power clean training. Winchester et al. (39) reported that both kinematics of the bar and kinetic variables specific to the power clean improve with training and feedback.

This study investigated the application of AO on facilitating the learning (kinematics) and performance (kinetics) of athletes in a novel and technical exercise (power clean) by using portable and readily available video playback technology to facilitate the AO process. The aim of this research was to determine (a) whether the use of AO would better/faster facilitate the learning of a complex novel RT exercise and (b) whether improvements in performance were associated with an improvement in lifting technique. It was hypothesized that the group who received AO to facilitate learning would improve power clean technique (kinematics) faster than the traditional coaching (TC) group. It was also hypothesized that improvement in power clean technique will be associated with improvements in power clean performance (kinetics).

With limited literature reporting the use of AO in the RT environment, this is the first study to investigate the influence of AO on learning the correct lifting technique of the power clean exercise. The aim for this study was to provide evidence for S&C coaches to apply more efficient practices (e.g., AO) when teaching the power clean exercise to their athletes. To the best of our knowledge, this is also the first study to investigate whether performance of the power clean is enhanced as a result of improved lifting technique in the power clean exercise. This will allow S&C coaches to appreciate the performance benefits, not only the safety benefits of lifting with good technique.

Methods

Experimental Approach to the Problem

A randomized between groups with repeated measures study design was used to test the hypothesis that the group who received AO to facilitate learning would improve power clean technique (kinematics) faster than the TC group. Kinematic (process measures) and kinetic (mean peak power output [PPO]) data were collected before intervention, at the end of weeks 2 and 3, and after intervention at the completion of week 4. Subjects were randomly assigned to 2 groups (TC and AO) and underwent the training intervention during the general preparation phase of the annual periodized program to limit the effects of "other training" being performed by subjects.

Subjects

Subjects ( n = 15, mean ± SD; age: 20.9 ± 2.3 years, height: 183.4 ± 8.4 cm, body mass: 83.1 ± 6.4 kg) and 1 skilled model (age: 24 years, height: 179 cm, body mass: 82 kg) were recruited from 1 elite, state-level Australian football club. The football club provided written support to use their athletes in the study. All subjects were briefed on the potential risks associated with their involvement in the study and provided written informed consent before participation. All methods were approved by the Victoria University Human Research Ethics Committee and were conducted according to the standards established by the Declaration of Helsinki. Selection criteria for subjects to be included in this study were trained men aged between 18-30 years, but with no experience (novice) performing or receiving formal coaching of the power clean exercise. Subjects were excluded from the study if they were untrained (to reduce the potential of muscle damage) and had a musculoskeletal injury within the previous 6 months before participating in this study. After pretesting, subjects were allocated, through alternate assignment, into 2 groups: the AO group ( n = 8) and the TC group ( n = 7).

Equipment

Barbell and Resistance

Subjects performed the power clean exercise with a standard Olympic barbell weighing 20 kg. Pilot testing indicated that an additional 10 kg added to the barbell would provide a moderately challenging resistance while also being safe for novice subjects during learning. The additional 10-kg load was made up from a 2.5-kg weight plate added to each side of the barbell. Also added to each side of the barbell were two 2.5-kg custom-made translucent training discs (made of clear Perspex), which were designed to the same dimensions as a standard 20-kg Olympic-sized weight plate. This allowed for an unobstructed view of body segment positions during performance and later analysis of the power clean, and a starting height of the barbell at the same level as if there were 20-kg Olympic-sized weight plates on each side of the barbell. The 30-kg total load of the barbell was unchanged throughout the training and testing phase.

Video Cameras

All test trials performed by the subjects and the skilled model were video recorded at 25 frames per second. Two video cameras were set up on tripods; one 90° lateral to the right side of the subject/model (Panasonic, Osaka, Japan) and the other one directly in front to the subject/model (JVC, Yokohama, Japan). The skilled model was video recorded on 1 occasion, during the preparatory phase of the study. Subjects were recorded performing the power clean exercise during a pretest, at the end of weeks 2 and 3, and a post-test taken at the end of week 4.

Tendo Unit

A weightlifting analyzer (Tendo Sports Machines, Trenčín, Slovak Republic) was used to provide power clean performance data. The Tendo unit attaches to the barbell and provides instantaneous data on PPO (Watts) that were taken during pretest, at the end of weeks 2 and 3, and during the post-test at the end of week 4. The Tendo unit's microcomputer settings were set up to the manufacturer's recommendations for Olympic lifting exercises.

Procedures

Subjects attended 12 training sessions over a 4-week period (3 sessions per week, including a pretesting, post-testing, and familiarization session). All the power clean training sessions were conducted in the early evening, before the subjects commencing their formal football training sessions. All subjects performed the power clean exercise for 3 sets of 5 repetitions with 2 minutes rest between sets. Baechle and Earle's (3) power clean technique coaching cues were used as the reference to formulate the coaching cues provided to the subjects.

Subjects were introduced to the power clean exercise during the familiarization session that was the first of the 12 sessions and included a demonstration and the basic coaching cues of the exercise. The selected number of repetitions (5) was at the higher end of the 3 to 5 repetitions recommended by Baechle and Earle (3) for power training, and also relates to Carrol and Bandura's (9) findings that higher repetitions result in more accurate reproductions of the movement and better facilitates the learning process. The AO group watched the skilled model (AO intervention) 5 times before performing each set, which was the same number of repetitions subjects were required to physically perform.

Video, from the sagittal and frontal planes, of a skilled performer (model), performing 3 sets of 5 repetitions of power clean trials was collected and used as the vision shown to the subjects from the AO group during the study. Video editing software, Final Cut Pro (Apple, Inc., Cupertino, CA, USA) was used to synchronize the sagittal plane footage with the frontal plane footage, and the 2 video angles were put side by side in a split screen video. The video footage of the skilled model performing 5 repetitions of the power clean was shown to the experimental group on a tablet computer (iPad 2; Apple, Inc., USA).

Before training and testing sessions, subjects undertook a general and standardized warm-up of 1 set of 10 deadlifts with the same barbell and load that was used to perform the power clean, followed by 1 set of 10 body weight squats and 1 set of 5 body weight jump squats, all with 1 minute rest between each exercise. The TC group received verbal coaching cues that would be considered standard practice when coaching in the field, whereas the AO group also received verbal coaching cues, but observed video of the skilled model presented on a tablet computer. The AO group was exposed to 5 repetitions on each occasion of watching the skilled model vision (AO intervention), which was the same number of repetitions subjects were required to physically perform (total of 15 in 3 sets of 5 repetitions). The AO intervention was administered before commencing the first, second, and third set.

Only the testing sessions of the subjects were recorded for analyses. During these sessions, subjects wore plain black compression tights and a plain black long sleeved compression top (Slazenger, Shirebrook, England) on which key joint center landmarks were placed for kinematic analysis. The compression garments provided freedom of movement but minimized joint center marker movement while performing the power clean exercise.

Statistical Analyses

Kinematic (process measures, which are the steps involved in completing a task or skill such as a power clean, e.g., hip angle) and kinetic (mean peak power output) data were analyzed off-line. Power clean technique data were measured using the criteria listed in Table 1. Differences in process measures and performance for each repetition were averaged for the 15 repetitions for each time point (before intervention, at the end of weeks 2 and 3, and after intervention). Video recordings of testing sessions were analyzed using a biomechanical video analysis software (Kinovea version 0.8.15, technique process measures of the power clean exercise such as joint angles and distances. www.kinovea.org). This software enabled the analysis of

To determine whether technique changed over time, each dependent variable was analyzed separately using linear mixed modeling with group (TC and AO) as a fixed factor and week, set, and repetition as repeated measures (12). The fit of the model was adjusted by inclusion of random intercepts and slopes, changing the variance structure, and removing nonsignificant effects and goodness-of-fit between models was compared using Akaike information criterion. This analysis allowed us to determine the relative change within each group over time and differences between instruction methods. Effect sizes were calculated using Cohen's d. Post hoc tests for significant effects were followed up using a Bonferroni correction with significance set at p ≤ 0.05.

Results

All subjects involved in the study completed the training intervention of the 12 sessions, including testing, with no reports of injuries being sustained.

Kinetic Changes

Table 2 shows group-by-time interaction results for mean peak power output (Watts), which was used as a measure of power clean performance. Mean peak power output significantly changed over time, F (3,141.51) = 22.80, p < 0.001. Changes across time showed that mean peak power increased significantly from pretest to the end of week 2 (M Δ = 34.501, SE = 8.43, p < 0.001), the end of week 3 (M Δ = 66.09, SE = 10.49, p < 0.001), and the post-test (M Δ = 86.10, SE = 10.94, p < 0.001). There was a significant increase in peak power from the end of week 2 to the end of week 3 (M Δ = 31.59, SE = 9.87, p = 0.010) and from the end of week 2 to the post-test (M Δ = 51.60, SE = 10.76, p < 0.001). The interaction of group and time was not statistically significant, F (3,141.51) = 1.65, p = 0.180.

Kinematic Changes

Changes in kinematic variables across the intervention are summarized in Figures 1-5.

1. Strength and conditioning coaches can assist athlete development by using video playback technology (e.g., tablet computers) to demonstrate appropriate technique. Although video feedback is not an innovative practice per se, its practical use has been limited because of cost and portable access. Inexpensive, portable, and flexible playback technologies can be positioned throughout the gym by S&C coaches to assist coaching and refining of RT exercise technique.

2. The application of AO in team environments can be an effective way of managing large athlete:coach ratios. Providing athletes with an elite model demonstrating correct technique can provide athletes with a reference for correctness that can be viewed as often as an athlete chooses when the coach is unavailable and can be a more efficient use of time.

3. Complex RT exercises, like the power clean, can benefit from the use of AO. Using the approach demonstrated in this study, coaches can include complex lifts in training programs that they may have previously excluded.

Copyright © 2014 by the National Strength & Conditioning Association.

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# data[].attributes.attachment_link.title
Kinematic and Kinetic Improvements Associated With Action... : The Journal of Strength & Conditioning Research

# data[].attributes.attachment_link.description
ilitating learning of the power clean technique (kinematics) compared with traditional strength coaching methods and whether improvements in performance (kinetics) were associated with an improvement in lifting technique. Fifteen subjects (age, 20.9 ± 2.3 years) with no experience in performing the power clean exercise attended 12 training and testing sessions over a 4-week period.

# data[].attributes.attachment_link.readable_text
Sakadjian, Alex 1,2; Panchuk, Derek 1,3; Pearce, Alan J. ⁴

doi: 10.1519/JSC.0000000000000290

Sakadjian, A, Panchuk, D, and Pearce, AJ. Kinematic and kinetic improvements associated with action observation facilitated learning of the power clean in Australian footballers. J Strength Cond Res 28(6): 1613-1625, 2014-This study investigated the effectiveness of action observation (AO) on facilitating learning of the power clean technique (kinematics) compared with traditional strength coaching methods and whether improvements in performance (kinetics) were associated with an improvement in lifting technique. Fifteen subjects (age, 20.9 ± 2.3 years) with no experience in performing the power clean exercise attended 12 training and testing sessions over a 4-week period. Subjects were assigned to 2 matched groups, based on preintervention power clean performance and performed 3 sets of 5 repetitions of the power clean exercise at each training session. Subjects in the traditional coaching group (TC; n = 7) received the standard coaching feedback (verbal cues and physical practice), whereas subjects in the AO group ( n = 8) received similar verbal coaching cues and physical practice but also observed a video of a skilled model before performing each set. Kinematic data were collected from video recordings of subjects who were fitted with joint center markings during testing, whereas kinetic data were collected from a weightlifting analyzer attached to the barbell. Subjects were tested before intervention, at the end of weeks 2 and 3, and at after intervention at the end of week 4. Faster improvements (3%) were observed in power clean technique with AO-facilitated learning in the first week and performance improvements (mean peak power of the subject's 15 repetitions) over time were significant ( p < 0.001). In addition, performance improvement was significantly associated ( R ² = 0.215) with technique improvements. In conclusion, AO combined with verbal coaching and physical practice of the power clean exercise resulted in significantly faster technique improvements and improvement in performance compared with traditional coaching methods.

¹ College of Sport and Exercise Science, Victoria University, Melbourne, Australia;

² Melbourne Football Club, Melbourne, Australia;

³ Institute of Sport, Exercise, and Active Living, Victoria University, Melbourne, Australia; and

⁴ Cognitive and Exercise Neuroscience Unit, Center for Mental Health and Wellbeing, School of Psychology, Deakin University, Melbourne, Australia

Address correspondence to Alex Sakadjian, alex.sakadjian@live.vu.edu.au.

Introduction

Commonly referred to as demonstration, observational learning, or modeling (16), action observation (AO) can be defined as the interaction between a model and an observer. The actions of a model are viewed, causing adaptations of the observer's behaviors to match the outcomes and processes of the events demonstrated by the model (16,17,21,37). Horn and Williams (17) propose that for effective skill acquisition to be achieved, the transfer of information from instructor to learner is critical. In skill acquisition, the most common mode of information transfer is demonstration, from which the general movement patterns of the skill are observed by the learner (21,38). Action observation has been used as an effective method of communicating this information from instructor to learner, especially to novice learners (21).

Most AO-related studies have focused on fine, simple, or sport-specific skills and investigations have provided support to using AO for improving motor skills in both elite (5) and novice (2) level athletes. Buccino et al. (7) who investigated musically naive subjects observing an expert model playing guitar chords, demonstrated that through the use of AO, novel motor patterns can be developed. Similarly, Porro et al. (27) demonstrated that force production was increased after an AO intervention despite no physical training of the muscle tested. The investigation by Porro et al. (27) was one of the few studies found in the literature that investigated and reported changes to kinetic variables as a result of an AO intervention. The study was well controlled, and the improved muscle force results can be strongly attributed to the AO intervention; however, the muscle and motor skill that was investigated lacked specificity to athletic- or sport-related motor skills and muscles. The benefits of AO have also been used to investigate sport-specific skill acquisition. Weeks and Anderson (36) reported that improvements in the acquisition and retention of an overhead volleyball serve after exposure to video footage of a model performing the same skill with ideal form. The subjects in the study had either never performed the skill before or had not practiced the skill in the previous 3 years, which provides evidence of the benefits of AO in learning a skill and then retaining the learned skill for novice or detrained individuals. Baudry et al. (5) also investigated AO-facilitated learning of a sports skill, reporting greater improvements in gymnastic pommel horse technique for the group that received video modeling and feedback than the control group who did not.

The evidence discussed above demonstrates the beneficial impact that AO can have on learning a new motor skill and the subsequent improvements in performance of that motor skill. However, it is apparent that the benefits of using the AO concept have received limited research in a resistance training (RT) environment that is specific to sport performance, despite the obvious requirements for athletes to learn proper lifting techniques to improve strength and power qualities. Strength and conditioning (S&C) is a vital aspect of athletic preparation, especially at the elite levels of competition. The professional standards and guidelines of the National Strength and Conditioning Association (26) has made recommendations on athlete:S&C coach ratios and presented data across various sports athlete:S&C coach ratios; which vary between 3 and 14.8 athletes to 1 coach. The recommendations and guidelines do, however, suggest increased supervision for novice athletes, or athletes who have no experience in technical lifts, such as the power clean. Anecdotal evidence has suggested that in club-based sports systems, where the opportunities to fund S&C coaches is limited, working with large athlete:S&C coach ratios (i.e., 1:25) is not uncommon, making teaching and appropriate supervision of the technical aspects of RT exercises challenging. Taking the time to provide athletes proper technique coaching has, at times, been considered inefficient use of time for S&C staff (who need to supervise a number of athletes concurrently) and has provided a rationale for S&C coaches to question the prescription of exercises such as the power clean from the athletic conditioning program altogether, replacing them with simpler (e.g., squat jump) exercises. With the positive effects of AO-facilitated learning reported in skill acquisition literature, the application of AO theory to S&C practices of athletes could potentially assist S&C coaches in facilitating the learning of athletes in novel and technical exercises.

In terms of AO effects related to RT, Ram et al. (28) found that technique was improved for novice learners in groups that were exposed to observing a model with ideal form for both a barbell squat exercise and a balancing skill while also reporting an improvement in movement outcome for the barbell squat task. McCullagh and Meyer (25) also used a barbell squat exercise with a cohort that had never performed free weight squats previously; they reported that the observation of either skilled or novice models resulted in improved learning of the squat exercise with marginally greater improvement in form for the group that observed skilled models. Rucci and Tomporowski (30) investigated the effect of 3 different types of augmented feedback (video-only, verbal-only, and video-verbal) on hang power clean technique. The video-only and video-verbal feedback groups watched a video of themselves after performing each set of the exercise, therefore a self-model design AO intervention. Results demonstrated an improvement in hang power clean technique for both verbal-only feedback and video-verbal feedback groups, whereas the video-only group failed to show improvement in technique. Perhaps the RT study most similar to this study was performed by Winchester et al. (39) who investigated changes in bar-path kinematics specific to power clean technique while also investigating whether changes were also seen in kinetic variables after 4 weeks of power clean training. Winchester et al. (39) reported that both kinematics of the bar and kinetic variables specific to the power clean improve with training and feedback.

This study investigated the application of AO on facilitating the learning (kinematics) and performance (kinetics) of athletes in a novel and technical exercise (power clean) by using portable and readily available video playback technology to facilitate the AO process. The aim of this research was to determine (a) whether the use of AO would better/faster facilitate the learning of a complex novel RT exercise and (b) whether improvements in performance were associated with an improvement in lifting technique. It was hypothesized that the group who received AO to facilitate learning would improve power clean technique (kinematics) faster than the traditional coaching (TC) group. It was also hypothesized that improvement in power clean technique will be associated with improvements in power clean performance (kinetics).

With limited literature reporting the use of AO in the RT environment, this is the first study to investigate the influence of AO on learning the correct lifting technique of the power clean exercise. The aim for this study was to provide evidence for S&C coaches to apply more efficient practices (e.g., AO) when teaching the power clean exercise to their athletes. To the best of our knowledge, this is also the first study to investigate whether performance of the power clean is enhanced as a result of improved lifting technique in the power clean exercise. This will allow S&C coaches to appreciate the performance benefits, not only the safety benefits of lifting with good technique.

Methods

Experimental Approach to the Problem

A randomized between groups with repeated measures study design was used to test the hypothesis that the group who received AO to facilitate learning would improve power clean technique (kinematics) faster than the TC group. Kinematic (process measures) and kinetic (mean peak power output [PPO]) data were collected before intervention, at the end of weeks 2 and 3, and after intervention at the completion of week 4. Subjects were randomly assigned to 2 groups (TC and AO) and underwent the training intervention during the general preparation phase of the annual periodized program to limit the effects of "other training" being performed by subjects.

Subjects

Subjects ( n = 15, mean ± SD; age: 20.9 ± 2.3 years, height: 183.4 ± 8.4 cm, body mass: 83.1 ± 6.4 kg) and 1 skilled model (age: 24 years, height: 179 cm, body mass: 82 kg) were recruited from 1 elite, state-level Australian football club. The football club provided written support to use their athletes in the study. All subjects were briefed on the potential risks associated with their involvement in the study and provided written informed consent before participation. All methods were approved by the Victoria University Human Research Ethics Committee and were conducted according to the standards established by the Declaration of Helsinki. Selection criteria for subjects to be included in this study were trained men aged between 18-30 years, but with no experience (novice) performing or receiving formal coaching of the power clean exercise. Subjects were excluded from the study if they were untrained (to reduce the potential of muscle damage) and had a musculoskeletal injury within the previous 6 months before participating in this study. After pretesting, subjects were allocated, through alternate assignment, into 2 groups: the AO group ( n = 8) and the TC group ( n = 7).

Equipment

Barbell and Resistance

Subjects performed the power clean exercise with a standard Olympic barbell weighing 20 kg. Pilot testing indicated that an additional 10 kg added to the barbell would provide a moderately challenging resistance while also being safe for novice subjects during learning. The additional 10-kg load was made up from a 2.5-kg weight plate added to each side of the barbell. Also added to each side of the barbell were two 2.5-kg custom-made translucent training discs (made of clear Perspex), which were designed to the same dimensions as a standard 20-kg Olympic-sized weight plate. This allowed for an unobstructed view of body segment positions during performance and later analysis of the power clean, and a starting height of the barbell at the same level as if there were 20-kg Olympic-sized weight plates on each side of the barbell. The 30-kg total load of the barbell was unchanged throughout the training and testing phase.

Video Cameras

All test trials performed by the subjects and the skilled model were video recorded at 25 frames per second. Two video cameras were set up on tripods; one 90° lateral to the right side of the subject/model (Panasonic, Osaka, Japan) and the other one directly in front to the subject/model (JVC, Yokohama, Japan). The skilled model was video recorded on 1 occasion, during the preparatory phase of the study. Subjects were recorded performing the power clean exercise during a pretest, at the end of weeks 2 and 3, and a post-test taken at the end of week 4.

Tendo Unit

A weightlifting analyzer (Tendo Sports Machines, Trenčín, Slovak Republic) was used to provide power clean performance data. The Tendo unit attaches to the barbell and provides instantaneous data on PPO (Watts) that were taken during pretest, at the end of weeks 2 and 3, and during the post-test at the end of week 4. The Tendo unit's microcomputer settings were set up to the manufacturer's recommendations for Olympic lifting exercises.

Procedures

Subjects attended 12 training sessions over a 4-week period (3 sessions per week, including a pretesting, post-testing, and familiarization session). All the power clean training sessions were conducted in the early evening, before the subjects commencing their formal football training sessions. All subjects performed the power clean exercise for 3 sets of 5 repetitions with 2 minutes rest between sets. Baechle and Earle's (3) power clean technique coaching cues were used as the reference to formulate the coaching cues provided to the subjects.

Subjects were introduced to the power clean exercise during the familiarization session that was the first of the 12 sessions and included a demonstration and the basic coaching cues of the exercise. The selected number of repetitions (5) was at the higher end of the 3 to 5 repetitions recommended by Baechle and Earle (3) for power training, and also relates to Carrol and Bandura's (9) findings that higher repetitions result in more accurate reproductions of the movement and better facilitates the learning process. The AO group watched the skilled model (AO intervention) 5 times before performing each set, which was the same number of repetitions subjects were required to physically perform.

Video, from the sagittal and frontal planes, of a skilled performer (model), performing 3 sets of 5 repetitions of power clean trials was collected and used as the vision shown to the subjects from the AO group during the study. Video editing software, Final Cut Pro (Apple, Inc., Cupertino, CA, USA) was used to synchronize the sagittal plane footage with the frontal plane footage, and the 2 video angles were put side by side in a split screen video. The video footage of the skilled model performing 5 repetitions of the power clean was shown to the experimental group on a tablet computer (iPad 2; Apple, Inc., USA).

Before training and testing sessions, subjects undertook a general and standardized warm-up of 1 set of 10 deadlifts with the same barbell and load that was used to perform the power clean, followed by 1 set of 10 body weight squats and 1 set of 5 body weight jump squats, all with 1 minute rest between each exercise. The TC group received verbal coaching cues that would be considered standard practice when coaching in the field, whereas the AO group also received verbal coaching cues, but observed video of the skilled model presented on a tablet computer. The AO group was exposed to 5 repetitions on each occasion of watching the skilled model vision (AO intervention), which was the same number of repetitions subjects were required to physically perform (total of 15 in 3 sets of 5 repetitions). The AO intervention was administered before commencing the first, second, and third set.

Only the testing sessions of the subjects were recorded for analyses. During these sessions, subjects wore plain black compression tights and a plain black long sleeved compression top (Slazenger, Shirebrook, England) on which key joint center landmarks were placed for kinematic analysis. The compression garments provided freedom of movement but minimized joint center marker movement while performing the power clean exercise.

Statistical Analyses

Kinematic (process measures, which are the steps involved in completing a task or skill such as a power clean, e.g., hip angle) and kinetic (mean peak power output) data were analyzed off-line. Power clean technique data were measured using the criteria listed in Table 1. Differences in process measures and performance for each repetition were averaged for the 15 repetitions for each time point (before intervention, at the end of weeks 2 and 3, and after intervention). Video recordings of testing sessions were analyzed using a biomechanical video analysis software (Kinovea version 0.8.15, technique process measures of the power clean exercise such as joint angles and distances. www.kinovea.org). This software enabled the analysis of

To determine whether technique changed over time, each dependent variable was analyzed separately using linear mixed modeling with group (TC and AO) as a fixed factor and week, set, and repetition as repeated measures (12). The fit of the model was adjusted by inclusion of random intercepts and slopes, changing the variance structure, and removing nonsignificant effects and goodness-of-fit between models was compared using Akaike information criterion. This analysis allowed us to determine the relative change within each group over time and differences between instruction methods. Effect sizes were calculated using Cohen's d. Post hoc tests for significant effects were followed up using a Bonferroni correction with significance set at p ≤ 0.05.

Results

All subjects involved in the study completed the training intervention of the 12 sessions, including testing, with no reports of injuries being sustained.

Kinetic Changes

Table 2 shows group-by-time interaction results for mean peak power output (Watts), which was used as a measure of power clean performance. Mean peak power output significantly changed over time, F (3,141.51) = 22.80, p < 0.001. Changes across time showed that mean peak power increased significantly from pretest to the end of week 2 (M Δ = 34.501, SE = 8.43, p < 0.001), the end of week 3 (M Δ = 66.09, SE = 10.49, p < 0.001), and the post-test (M Δ = 86.10, SE = 10.94, p < 0.001). There was a significant increase in peak power from the end of week 2 to the end of week 3 (M Δ = 31.59, SE = 9.87, p = 0.010) and from the end of week 2 to the post-test (M Δ = 51.60, SE = 10.76, p < 0.001). The interaction of group and time was not statistically significant, F (3,141.51) = 1.65, p = 0.180.

Kinematic Changes

Changes in kinematic variables across the intervention are summarized in Figures 1-5.

1. Strength and conditioning coaches can assist athlete development by using video playback technology (e.g., tablet computers) to demonstrate appropriate technique. Although video feedback is not an innovative practice per se, its practical use has been limited because of cost and portable access. Inexpensive, portable, and flexible playback technologies can be positioned throughout the gym by S&C coaches to assist coaching and refining of RT exercise technique.

2. The application of AO in team environments can be an effective way of managing large athlete:coach ratios. Providing athletes with an elite model demonstrating correct technique can provide athletes with a reference for correctness that can be viewed as often as an athlete chooses when the coach is unavailable and can be a more efficient use of time.

3. Complex RT exercises, like the power clean, can benefit from the use of AO. Using the approach demonstrated in this study, coaches can include complex lifts in training programs that they may have previously excluded.

Copyright © 2014 by the National Strength & Conditioning Association.

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