Sex-Based Comparisons of Hamstrings-to-Quadriceps Ratio Across the Velocity Spectrum.

Background: Women are typically more prone to knee injuries than men, possibly due to poorer hamstrings-to-quadriceps ratio (HTQ), particularly during fast velocity movements.

Hypothesis: Men would have greater HTQ across velocity than women.

Study design: Cross-sectional study.

Level of evidence: 2.

Methods: Ultrasound images quantified quadriceps and hamstrings muscle cross-sectional area (CSA) in 27 study participants (14 women, age, 24 ± 4 years; 13 men, age, 25 ± 6 years). Peak torque (PT) was taken from maximal voluntary isometric contractions (MVICs) and isokinetic leg extension and flexion contractions from 60° to 300° s^-1. Independent samples t-tests examined differences in CSA and HTQ from CSA. Mixed-factorial ANOVAs examined differences in PT and HTQ from PT.

Results: Men had larger CSA and PT than women for leg extension and flexion across velocity (P < .01). There were no sex-based differences in the HTQ from CSA or PT across velocity (P ≥ .11). For both groups, leg extension PT decreased from MVIC to 300° s^-1 (P ≤ .04). For women, leg flexion PT was the same from MVIC to 60° s^-1 (P > .98), decreased from 60° to 180° s^-1 (P < .01), and plateaued from 180° to 300° s^-1 (P ≥ .07). For men, leg flexion PT decreased from MVIC to 300° s^-1 (P ≤ .03). For both groups, HTQ increased from MVIC to 60° s^-1 (P < .01), then plateaued from 60° to 300° s^-1 (P > .98).

Conclusion: Both groups had similar patterns of response for leg extension PT and HTQ across velocity, with no sex-based differences for HTQ. Factors other than HTQ may account for the potential sex-based difference in knee injury risk.

Clinical relevance: Increased knee injury predisposition for women compared with men may be due to neuromuscular control or anatomy rather than HTQ.