Purpose: To examine and compare sex-related differences in the functioning of the hamstrings and quadriceps muscles and the isokinetic hamstrings eccentric-to-quadriceps concentric functional ratio (H/Q FUNC).
Methods: Fifty male and 46 female young adults completed this study. Each participant carried out an isokinetic assessment to determine isokinetic concentric and eccentric torques during knee extension and flexion actions at 3 different angular velocities (60, 180 and 300°/s) adopting a lying position. The H/Q FUNC was calculated using peak torque (PT) values and 3 different joint-angle-specific torque values (15°, 30° and 45° of knee extension). A repeated measures analysis of variance was used to compare the results, and post hoc analyses using Friedman correction were employed.
Results: There were statistically significant effects of angular velocity, joint angle and sex on the H/Q FUNC (p < 0.01). Thus, the H/Q FUNC ratio in both males and females decreases closer to full knee extension and with increasing movement velocity. The H/Q FUNC was also significantly lower in females compared to males, irrespective of moment velocity and joint angle.
Conclusions: The findings of the current study reinforce the need to examine the H/Q FUNC ratio closer to full knee extension (where knee injury is most likely to occur) rather than using PT values which may not be as informative, as well as to focus preventive and rehabilitation training programmes on reducing quadriceps dominance by enhancing eccentric hamstring strength (especially in females who are at higher risk of injury).
Level of evidence: III.
Keywords: Anterior cruciate ligament; Injury prevention; Isokinetic; Strength; Torque.