THE EFFECT OF QUADRICEPS FEMORIS, HAMSTRING, AND PLACEBO ECCENTRIC FATIGUE ON KNEE AND ANKLE DYNAMICS DURING CROSSOVER CUTTING

This study attempted to determine the effect oi eccentric quadriceps f emoris, hamstring, and placebo fatigue on stance limb dynamics during the plant-and-cut phase of a crossover cut Twenty female college stude nts (task trained were tested. Hamstring fatigue resulted in decreased peak impact knee flexion moments (p less than or equal to .01), incre ased internal tibial rotation at peak knee flexion (p less than or equ al to 05), and decreased peak ankle dorisflexion (p less than or equal to .05). Quadriceps fatigue resulted in increased peak ankle dorsifle xion moments (p < .01), decreased peak posterior braking forces (p les s than or equal to 01), decreased peak knee extension moments (p less than or equal to .01), delayed peak knee flexion (p less than or equal to .01), delayed peak propulsive forces (p < .01), and delayed subtal ar peak inversion moments (p less than or equal to .05). Fatigue of ei ther muscle group produced earlier peak ankle plantar flexion moments (p less than or equal to .05) and decreased peak propulsive knee flexi on moments (p less than or equal to .05). Variables requiring further study (p less than or equal to .1) provide discussion data. Soleus, ga strocnemius, tibialis anterior, and deep posterior compartment calf mu scles serve as dynamic impact force attenuators, compensating for fati gued proximal muscles.