Hamstring–quadriceps strength ratio at different movement velocities in healthy young adults

Purpose: The aims of the study were: comparing the strength of the thigh muscles at 30°/s and 60°/s, comparing the hamstring to quadriceps ratio (H/Q) resulting from the two movement velocities, and calculating an optimum cut-off for H/Q at 30°/s. Methods: The study involved both legs of 29 healthy non-professional athletes aged 20 to 30 years, resulting in a total sample size of 58 legs. Maximum concentric torques and H/Q ratios were measured at angular velocities of 30°/s and 60°/s, with five repetitions per leg and a 60-s rest between phases. The statistical analysis included descriptive and inferential tests (Wilcoxon, T-test, Pearson correlation, linear regression model, receiver operating characteristics (ROC) analyses and agreement test), with statistical p-value significance set at 0.05. Results: At 30°/s, quadriceps and hamstring torques were higher compared to 60°/s, but there was no significant difference in the resulting H/Q. We found a positive correlation between the H/Q ratios at the two speeds (Pearson’s r = 0.796). Age, sex, body mass index (BMI), dominant leg, or activity level did not influence this ratio at 30°/s and at 60°/s. ROC models and agreement tests suggested an optimal cut-off value of 0.57 at 30°/s. Conclusions: Operating at the 30°/s velocity generated higher peak torques, while it maintained H/Q comparable to that obtained at the 60°/s velocity. This lower speed may make the isokinetic test more feasible during rehabilitation after ACL reconstruction surgery, especially for patients who struggle with a 60°/s test. However, when using 30°/s, the conventional H/Q cut-off should be set at 0.57.