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Running shoes are made from a combination of materials that vary with different shoes. The midsole generally consists of polyurethane surrounding another material such as gel or liquid silicone. Outsoles are usually made of carbon or blown rubber and the rest of the covering is usually a synthetic material such as artificial suede or a nylon weave with plastic slabs supporting the shape.

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Running is a sport that dates back thousands of years. Historians believe that competitive running first developed as part of religious festivals and one of the earliest competitions on record took place in Ireland at the Tailteann Games. Today, running is extremely popular in the forms of cross-country and track. While running it its own sport, it is also an essential part of many other sports such as soccer and basketball.

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- In general, running shoes last between six and twelve months. They are not sustainable and must be replaced frequently. This results in the constant need to make more shoes and to extract the natural resources required to manufacture them.

- Running shoe manufacturing factories require a lot of energy to run and produce a lot of pollution into the atmosphere. Sometimes, the energy that they use is created in ways that are harmful towards the environment, such as burning fossil fuels.

- Many running shoe companies have their products manufactured overseas in developing countries such as China. After the shoes are created, they must be distributed to the countries where they will be sold. The vehicles that are used in this process require a lot of fuel and release large amounts of greenhouse gasses into the atmosphere.
- Running shoes contain many non-biodegradable materials such as plastic and polyurethane foam. As a result, they are unable to fully decompose. When shoes become worn out, they are usually sent to landfills where they sit for hundreds of years and take up space that is being stolen from the region’s wildlife.

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- The running shoe industry is an important part of the economy that creates many jobs, both in Canada and overseas.

- Running shoes improve the performance of professional athletes, making the sport more competitive and exciting.

- Running shoes can prevent athletes from becoming injured as they are designed for balance, support  and traction.
- Running shoes make the sport of running more efficient and comfortable. This encourages more people to participate, keeping children active and fighting against obesity.

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All parts of the shoe improve an athletes performance but here are 4 of the most important:

Impact Zone Protector - This improves an athlete's performance by protecting and decreasing the load on their heel. It prevents the athlete from injury and improves the spring force in their step.

Outsole - This allows the runner to grip the ground which improves their performance by allowing them to reach the maximum distance from each stride.

Forefoot Cushion - This cushions the forefoot, allowing the ball of the runner's foot to push off the ground more comfortably and with a greater force.

Heel Cushion: This cushions the athlete's heel and improves the transfer of force and momentum from the back of the shoe to the front of the shoe.

All of these can be adjusted according to the athlete's running style, size and form.

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< 50 A.D. - Sandals were used to protect the wearer's feet;

little to no support existed.

1830 - Liverpool Rubber Company develops the plimsoll type shoe (sneakers).

1930-1940 - Various shoe companies add traction to their designs. Shoes are created separate for specific sports.

1970s - The jogging shoe greatly increases in popularity. Running shoe technology improves by having the different forces involved analyzed and by improving cushioning and support.

1990s - Running shoes begin to take today's look. The fashion factor is added, progressing them to their current appearance.

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There are many forces involved in running shoes:

Friction: Friction is created when the runner pushes off of the shoe. Friction wears at the outsole of the shoe, requiring it to be tough.

Compression: Compression is created when the runner steps on the shoe. This requires comforting to keep the runner's foot comfortable.

Torsion: Torsion is created when the runner either twists their foot or turns a corner. The shoe must resist this wich requires more torsional support.

Spring: Spring force is created by the shoe after the runner steps on the shoe and compresses it. It then must re-expand, creating spring force. The shoe must use this to its advantage to propel the runner forward.

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1. Upper - This is the "body" of the shoe that contains the runner's foot. It is usually made out of a light material that allows the athlete's foot to breathe.

2. Comfort Liner - This is a foamy layer that comforts the runner's foot.

3. Heel cushion - This is a cushion that provides extra support for the heel.

4. Forefoot cushion - This is a cushion that supports the ball of the foot for better sprinting.

5. Midsole - This is a layer that protects the runner's foot from impact.

6. Impact Zone Protector - This is a special part of the shoe that acts as a shock-absorber. It protects the heel from high impact.

7. Outsole - This is the bottom layer of shoe which allows the runner to grip the ground and prevents water from seeping in.

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As shown, running shoes can improve an athlete's performance by cushioning the initial impact and spreading the force.

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Shod Heel Strike Running with Force - Slow Motion

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This is the ground reaction force generated when heel strike running in shoes. Notice that this force trace has the impact transient characteristic of heel strikes (a nearly instantaneous, large force experienced at impact when heel striking). Shoes do reduce this impact force when heel striking, but does not eliminate it.

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Barefoot Heel Strike Running with Force - Slow Motion

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This is the ground reaction force generated when heel strike running barefoot. Notice that this force trace has the impact transient characteristic of heel strikes (a nearly instantaneous, large force experienced at impact when heel striking). Shoes do reduce this impact force when heel striking, but does not eliminate it.

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A breakdown of the running shoe: