Running is an impact sport; running is an act that exerts a force against the ground. The force against the ground provides traction and allows a body to "bounce" forward. The relationship between force and running speed is dependent on body weight, gait, stride mechanics and functionality of biological tissues: bone, ligament, tendon, skin and muscle.
Speed
Running can be competitive, whether breaking an Olympic World record or shaving off one minute from a personal record. A goal shared by many runners is to be faster; to run at greater speeds. Several theories on how humans can run faster have be tested and supported by scientific research.
Stride.
In the past, it was hypothesized to increase the speed of a running, the legs of the runner need to move faster, at a quicker rate. To increase the speed of a runner, the turnover -- how quickly each leg strikes the ground -- must increase. Sprinters develop outstanding runner speeds over a short distance; analysis of sprinters reveal longer strides, which increases the amount of forward distance. By applying greater forces to the ground, sprinters can reach top speeds. Evidence suggests the speed of a runner is affected by ground forces, not the rate of turnover of the legs.
Vertical Force and Center of Gravity
Humans have a center of gravity, which allows the body to keep upright. The center of gravity changes as humans walk, move, sit and stand. Sprinters, while running, have a low center of gravity; the upper body in slightly leaning foward. Joggers or recreational runners tend to carry a high center of gravity; the upper body is vertical. As the center of gravity moves from low to high, the vertical force applied to the ground increases. As the vertical forces increases, running speeds decrease.
Summary
The amount of force exerted to the ground by the human body has an impact on speed. Vertical forces decrease a bodies ability to increase speed. Running speed is not associated with how rapid legs are turned over while running.
References
- "Clinical Biomechanics"; Relationship between vertical ground reaction force and speed during walking, slow jogging, and running; TS Keller et. all; July 1996
- "Journal of Applied Physiology"; Faster top running speeds are achieved with greater ground forces not more rapid leg movements; Peter G. Weyand et all.; March 2000
- "Physical Medicine & Rehabilitation Clinics of North America"; Biomechanics and analysis of running gait; SA Dugan et all.; August 2005
Member Comments