A kinetic analysis of sprinting.

To investigate the kinetics of sprinting, 15 male runners were filmed during a maximal effort sprint. The results were digitized, computer processed, and analyzed with interest focused on the muscle moment patterns about the ankle, knee, hip, shoulder, and elbow. The moments about the ankle consisted of minimal activity during the air phase to plantar flexor dominance during the ground phase. At the knee, the pattern demonstrated extensor to flexor dominance during the air phase, followed by flexor to extensor dominance during the ground phase. The hip moment pattern was composed of flexor to extensor activity during the air phase, then extensor to flexor dominance during ground contact. The magnitude of the lower limb joints indicated maximum exertion, with the highest values occurring during eccentric contraction. The greatest effort was generated by the hip extensor/knee flexor muscle group during the initial portion of ground contact, which corresponds with the area of greatest sprint injury. The angular force generation about the shoulder consisted of alternate flexor to extensor activity (extensor to flexor activity about the opposite shoulder), while the elbow activity was dominated by the flexors, with only brief extensor supremacy. The relatively small upper limb muscle moments seem to relegate the arms to the simple role of maintaining balance.