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GRADES 9-12
DESIGN A RUNNING SHOE FOR A TRIATHLETE
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BACKGROUND INFORMATION:
Shoe and Court Interaction
The equal and opposite force does not necessarily travel back up your leg. The surface itself absorbs a portion of the force converting it to other forms of energy. Subsequently, athletic surfaces are rated not only for pace but also for the percentage of force reduction.
Laboratory tests have demonstrated force reductions compared to impact on concrete. Grass reduces the force by over 55 percent, clay and artificial turf about 25% and hard courts only about 5-10%. There is a correlation between pain, injury and surface hardness.
With a wide variety of court surface types, shoe requirements change with the court type. The primary difference is essentially the patterns on the bottom of the outsole. Examine the soles of your athletic shoes and you will most likely note multiple distinct patterns on the outsoles. The patterns reflect the varying roles the parts of your foot play in performance. The foot does not
apply pressure in a uniform manner and consequently,
the sole of the athletic shoe reflects this in its design.
There are a variety of traction patterns on the soles of athletic shoes. Traction (the amount of resistance to slip between the shoe's outsole and the contact surface) like any other shoe characteristic must be commensurate and balanced with the sport. As one shoe designer described it, "If increasing traction were the major consideration suction cups could easily be employed on a sole." Some of the most common patterns are: the herringbone, ribbed (radially) and pillar, nub or dimpled. Pictured below are examples of these patterns.
Traction assists in starting, stopping and sideward motions. However, too much traction on the sole not only interferes with foot lift-off, but could subsequently transmit large pressures to the ankle and knees when landing from a jump or planting the foot down and result in injuries. Flat sections (seen in b) or suction pivots (seen in a) on the sole are often placed on for pivoting and turning.
The herringbone pattern has been the standard for most court sports and grips well on the surface. Pillared surfaces have dual functions. As the foot lands the first layer of the pillar grips the surface. During foot planting and stopping sufficient pressure is placed on the first layer of pillars to compress them. Pressing in the pillar exposes the second pillar, which provides more traction. Now the shoe sole has a much larger traction area for stopping.
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