Lower Extremity Kinematic and Kinetic Asymmetries during Countermovement Jumps in Healthy Division I Collegiate Athletes

Purpose: This study aimed to describe normative lower extremity kinematic and kinetic asymmetries in healthy athletes for commonly measured variables during a countermovement jump (CMJ) and to investigate the effect of sport and sex on these asymmetries. Methods: Routinely collected CMJ data were analyzed from healthy Division I collegiate athletes from 5 sports (cross-country, track, soccer, basketball, and American football) with no history of lower extremity surgery or recent lower extremity injury. Between-limb asymmetries were calculated for vertical ground reaction forces and sagittal plane joint excursions, joint moment impulses, and joint work during the braking, concentric, and landing phases of the CMJ. Separate multivariable linear regression models assessed associations between sex, sport, and asymmetry for each variable. Results: Data from 320 athletes were included (age: 19.2 ± 1.2 yr, males: 52%). Asymmetry magnitudes differed depending on the variable measured: Force-derived variable asymmetries ranged from 2% to 8%, joint excursion asymmetries were 1°–6°, joint moment impulse asymmetries were 4%–14%, and joint work asymmetries were 5%–17%. Joint excursion asymmetries were greatest at the ankle, and joint kinetic asymmetries were greatest at the knee. Sex and sport differences were observed, but the magnitudes of these differences were minimal and unlikely to be clinically meaningful. Conclusions: Between-limb asymmetries varied from 2% to 17% in healthy collegiate athletes, depending on the metric of interest; however, the magnitude of observed asymmetries did not vary meaningfully between males and females or between sports. Variable-specific asymmetries from this study can be used by sports medicine and athletic performance practitioners to identify individuals who exhibit abnormal magnitudes of asymmetry or to assess the recovery of CMJ symmetry following injury or surgery.