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 was conducted on 29 healthy non-professional athletes aged from 20 to 30. Both legs of the participants were assessed at angular velocities of 30°/s and 60°/s. Participants underwent a three-phase protocol: 3-minute warm-up on an elliptical machine, 30-second of whole-body vibration and isokinetic test using Technogym’s REV 7000 dynamometer. Maximum concentric torques and H/Q were measured at 30°/s and then at 60°/s, with five repetitions per leg and a 60-second rest between phases. Results At 30°/s, quadriceps and hamstring forces 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 (R = 0.796, p < 0.001). Age, sex, BMI, dominant leg, or activity level didn’t influence this ratio at 30°/s and at 60°/s. Receiver Operating Characteristic (ROC) models and agreement tests suggested an optimal cut-off value of 0.57 at 30°/s. Conclusions Operating at the 30°/s velocity generates higher peak torques, while it maintains 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-R 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.