The influence of fatigue on landing biomechanics in anterior cruciate ligament deficient (ACLD) patients is poorly understood. The purpose of this study was to examine the effect of fatigue on hip and knee joint biomechanics in deficient patients. Twelve ACLD males and 12 healthy control subjects participated in the study. The ACLD patients landed with increased peak knee flexion angle (F = 15.71, p < .01) and decreased peak knee flexion moment (F = 9.13, p < .01) after fatigue. Furthermore, ACLD patients experienced lower vertical ground reaction forces compared with controls regardless of fatigue state (F = 9.75, p < .01). It seems that ACLD patients use protective strategy in response to fatigue in order to prevent further injury in knee point.
