CONTEXT: Two-dimensional (or medial knee displacement (MKD)) and 3-dimensional (3D) knee valgus are theorized to contribute to anterior cruciate ligament injuries. However, whether these displacements can be improved in the double-legged squat (DLS) after an exercise intervention is unclear. OBJECTIVE: To determine if MKD and 3D knee valgus are improved in a DLS after an exercise intervention. DESIGN: Randomized controlled clinical trial. SETTING: Research laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 32 participants were enrolled in this study and were randomly assigned to the control (n = 16) or intervention (n = 16) group. During a DLS, all participants demonstrated knee valgus that was corrected with a heel lift. INTERVENTION(S): The intervention group completed 10 sessions of directed exercise that focused on hip and ankle strength and flexibility over a 2- to 3-week period. MAIN OUTCOME MEASURE(s): We assessed MKD and 3D knee valgus during the DLS using an electromagnetic tracking system. Hip strength and ankle-dorsiflexion range of motion were measured. Change scores were calculated for MKD and 3D valgus at 0%, 10%, 20%, 30%, 40%, and 50% phases, and group (2 levels)-by phase (6 levels) repeated-measures analyses of variance were conducted. Independent t tests were used to compare change scores in other variables (alpha < 0.05). RESULTS: The MKD decreased from 20% to 50% of the DLS (p = 0.02) and 3D knee valgus improved from 30% to 50% of the squat phase (p = 0.001). Ankle-dorsiflexion range of motion (knee extended) increased in the intervention group (p = 0.009). No other significant findings were observed (p > 0.05). CONCLUSIONS: The intervention reduced MKD and 3D knee valgus during a DLS. The intervention also increased ankle range of motion. Our inclusion criteria might have limited our ability to observe changes in hip strength.

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