Muscle strength and qualitative jump-landing differences in male and female military cadets: the jump-ACL study

Recent studies have focused on gender differences in movementpatterns as risk factors for acl injury. understanding intrinsicand extrinsic factors which contribute to movement patterns iscritical to acl injury prevention efforts. isometric lowerextremitymuscular strength, anthropometrics, and jump-landingtechnique were analyzed for 2,753 cadets (1,046 female, 1,707male) from the u.s. air force, military and naval academies.jump-landings were evaluated using the landing error scoringsystem (less), a valid qualitative movement screening tool.we hypothesized that distinct anthropometric factors (q-angle,navicular drop, bodyweight) and muscle strength would predictpoor jump-landing technique in males versus females, and thatfemale cadets would have higher scores (more errors) on aqualitative movement screen (less) than males. mean lessscores were significantly higher in female (5.34 ± 1.51) versusmale (4.65 ± 1.69) cadets (p < 0.001). qualitative movementscores were analyzed using factor analyses, yielding five factors,or “patterns”, contributing to poor landing technique. femaleswere significantly more likely to have poor technique due tolanding with less hip and knee flexion at initial contact (p <0.001), more knee valgus with wider landing stance (p < 0.001),and less flexion displacement over the entire landing (p <0.001). males were more likely to have poor technique due tolanding toe-out (p < 0.001), with heels first, and with an asymmetricfoot landing (p < 0.001). many of the identified factorpatterns have been previously proposed to contribute to aclinjury risk. however, univariate and multivariate analyses ofmuscular strength and anthropometric factors did not stronglypredict less scores for either gender, suggesting that changingan athlete’s alignment, bmi, or muscle strength may not directlyimprove his or her movement patterns.