Differences in lower-limb alignment and muscle strength between the sexes during distance-specific single-leg hop tasks.
Masumi Yoshimoto
During predictable forward single-leg hops, females flexed their hips more and showed lower hip and knee muscle strength than males.
Knee alignment and landing force did not differ by sex.
Key findings
1Females demonstrated greater hip flexion angles than males during single-leg hop landings at all three distances (30%, 50%, and 80% of height), with the gap widening as distance increased (e.g., 66.34° vs 57.80° at 80%).
2Females had lower isometric strength than males in hip adduction (0.25 vs 0.28 kgf/kg), hip abduction (0.36 vs 0.43), knee flexion (0.26 vs 0.30), and knee extension (0.41 vs 0.47).
3No sex differences were found in peak vertical ground reaction force, knee valgus angle, knee valgus moment, or knee flexion angle at any hop distance.
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What it does not show
All participants were healthy university students, so the findings may not apply to competitive athletes, post-ACL-reconstruction patients, or other age groups. The task was a predictable forward hop. The authors note that sex differences in knee mechanics tend to be more pronounced in unanticipated or multidirectional tasks, so the absence of knee valgus differences here does not rule them out in more complex movements. Cross-sectional design: no causal link can be drawn between the observed movement patterns and ACL injury risk. The order of hop distances was chosen by each participant rather than randomized, which could introduce order or fatigue effects. Single site, 23 females, no blinding of assessors described.
Declared interests
No external funding was received. The authors declare no conflicts of interest.
The easy way to misread this
Do not read the absence of knee valgus differences as evidence that females do not carry knee valgus risk. The task was a predictable forward hop, and the authors themselves note that sex differences in frontal-plane knee mechanics tend to be more pronounced in unanticipated or multidirectional tasks.
Summarised by AI from the full paper, without a clinician reviewing it. Check it against the source before it changes what you do. Read it on PubMed →