The effect of arm swings on lower limb kinetics during single-leg forward, vertical, and backward hopping.

Single-leg forward hopping was commonly used to evaluate knee function and quadricep strength deficits following anterior cruciate ligament (ACL) injuries. Achieving similar hopping performance between legs was insufficient to support symmetrical knee function and quadricep strength in patients following ACL injuries, likely due to movement compensation. This study aimed to quantify the effects of arm swings on lower limb kinetics during single-leg forward, vertical, and backward hopping with a focus on knee assessment.