Compensatory Movement Strategies during the Rearfoot Elevated Split Squat after ACL Reconstruction

PURPOSE: To compare inter and intralimb compensation strategies between anterior cruciate ligament (ACL)-involved and noninvolved limbs during the rearfoot elevated split squat (RFESS) and examine the influence of trunk flexion angle on compensation strategy. METHODS: Twenty-five individuals (3.9 ± 0.9 months post-ACL reconstruction) performed RFESS using three-dimensional motion capture and force plates. Joint kinematics, kinetics, and vertical ground reaction forces (vGRF) were analyzed for the lead limb at the bottom position of the RFESS. Internal joint moments were normalized to body mass and vGRF were normalized to body weight. Relative joint contributions were calculated as ([joint moment/total support moment] × 100). Paired samples t tests assessed between-limb differences (adjusted P = 0.0038). Linear regression examined the relationship between trunk flexion angle and compensation strategy. RESULTS: The ACL-involved limb demonstrated both inter and intralimb compensation, reflected by lower vGRF (-7.3%, P < 0.001, d = -1.26) and total support moment (-0.29 N·m·kg -1 , P = 0.002, d = -0.72), alongside a redistribution of demand away from the knee (-12.8%, P