El-Ashker, Said and Carson, Brian P. and Ayala, Francisco and De Ste Croix, Mark B (2015). Sex- related differences in joint-angle-specific functional hamstring-to-quadriceps strength ratios. Knee

3 Purpose: To examine and compare sex-related differences in the functioning of the hamstrings 4 and quadriceps muscles and the isokinetic hamstrings eccentric to quadriceps concentric 5 functional ratio (H/QFUNC) . 6 Methods: Fifty male and 46 female young adults completed this study. Each participant carried 7 out an isokinetic assessment to determine isokinetic concentric and eccentric torques during 8 knee extension and flexion actions at 3 different angular velocities (60, 180 and 300o/s) 9 adopting a lying position. The H/QFUNC was calculated using peak torque (PT) values and 3 10 different joint angle-specific torque values (15o, 30o, and 45o of knee extension). A repeated 11 measures analysis of variance was used to compare the results and post hoc analyses using a 12 Friedman correction were employed. 13 Results: There were statistically significant effects of angular velocity, joint angle and sex for 14 the H/QFUNC (p<0.01). Thus, the H/QFUNC ratio in both males and females decreases closer to 15 full knee extension and with increasing movement velocity. The H/QFUNC was also significantly 16 lower in females compared to males, irrespective of moment velocity and joint angle. 17 Conclusions: The findings of the current study reinforce the need to examine the H/QFUNC ratio 18 closer to full knee extension (where knee injury is most likely to occur) rather than using PT 19 values which may not be as informative; as well as to focus preventive and rehabilitation 20 training programmes on reducing quadriceps dominance by enhancing eccentric hamstring 21 strength (especially in females who are at higher risk of injury). 22 Level of evidence III 23