(15) DOES GREATER MUSCLE STRENGTH AND SIZE RESULT IN GREATER HAMSTRINGS-TO-QUADRICEPS RATIO?

Hamstrings-to-quadriceps ratio (HTQ) can provide unique information regarding muscle development, training habits, and injury risk, particularly of the knee. Theoretically, males and females who are stronger and thus more strength trained should have greater HTQ, though this has not been well studied.

Purpose: The purpose of this study was to compare HTQ for females and males with above and below average thigh strength and muscle size during knee extension and flexion contractions.

Methods: Twenty-seven females and males (mean±95% confidence interval, n=14 females, age=24±4yrs; n=13 males, age=25±6yrs) participated. Ultrasound images quantified quadriceps, hamstrings, and thigh muscle cross-sectional area (CSA). Peak torque (PT) was taken from maximal voluntary isometric contractions (MVICs) and isokinetic knee extension and flexion contractions from 60-300°×s^-1. HTQ was calculated by dividing PT from knee flexion by PT from knee extension for all contractions. Total thigh strength (TTS) was calculated by adding knee extension MVIC PT and knee flexion MVIC PT. Total thigh muscle size (TTMS) was calculated by adding quadriceps CSA and hamstrings CSA. Mixed-factorial ANOVAs examined differences in HTQ for above vs. below average TTS and TTSM males and females.

Results: When split by TTS, there were no sex- or group-based differences for HTQ (p³0.349). For below average TTS females and males, HTQ did not change across velocity (p³0.060). For females with above average TTS, HTQ from 120-300°×s^-1 was greater than MVIC (p£0.017). For males with above average TTS, HTQ increased from MVIC to 60°×s^-1 (p=0.013) and then plateaued (p³0.082). When split by TTMS, there were no sex- or group-based differences for HTQ (p³0.276). When split by TTMS, HTQ increased from MVIC to 60°×s^-1 (p<0.001), and then plateaued (p=1.000) for all groups. CONCLUSIONS: The present study found that individuals with greater thigh strength and size did not have superior HTQ compared to individuals with lower muscle strength and size. However, it is possible that muscle strength and size may augment the velocity-related responses for HTQ, such that individuals with greater muscle strength and size may maintain greater HTQ as velocity increases. Furthermore, despite the fact that females tend to yield lower HTQs, the present study found no sex-based differences. Finally, it is worth noting that all groups tended to have HTQs below the recommended ratio of 0.67. PRACTICAL APPLICATIONS: Strength and conditioning coaches and professionals can utilize HTQ to gauge potential muscular imbalances and augment programming, but it should not be the entire basis for assessing potential knee injury risk among an entire team. The present study demonstrates that stronger, and likely more strength trained, individuals may not yield superior HTQ. Strength and conditioning coaches and sport scientists should consider examining HTQ in conjunction with anthropometric and biomechanical factors for a holistic understanding potential knee injury risk.

Acknowledgements: None