Fatigue-related changes in stance leg mechanics during sidestep cutting maneuvers

BackgroundThe increased number of women participating in sports has been paralleled by a greater knee injury rate in women compared to men. Among these injuries, those occurring to the anterior cruciate ligament are commonly observed during sidestep cutting maneuvers. In addition, general fatigue appears to correlate with injuries to the passive structures during a game. The purpose of the study was to examine the fatigue-related changes in lower limb mechanics during a cutting maneuver in female athletes.MethodsTwelve college female soccer players were recruited. Sidestep cutting maneuvers were performed prior to, and after a fatiguing exercise (60-min shuttle run). Fatigue state was evaluated by calculating power output from countermovement jumps performed before and after the shuttle run. Three-dimensional stance leg hip, knee and ankle kinematics and kinetics during the cutting task were calculated and reported as initial ground contact angle, ranges of motion and peak moments of the stance phase. Cutting maneuver stance leg mechanics were analyzed through repeated measures two-way ANOVAs (P < 0.05).FindingsJumping power output decrements suggested fatigue was induced. Sagittal and frontal planes kinematics and kinetics of the cutting task did not change after fatigue. In the transverse plane, the hip, knee and ankle joints were more externally rotated at touchdown, and during stance the knee underwent greater internal rotation.InterpretationIncreased knee internal rotation has potentially important implication for increased injury risk when combined with unexpected perturbation faced in a game. Also, the fact that the sub-maximal level of fatigue did not lead to greater dynamic changes suggests a possible threshold of fatigue before function is dramatically affected.