Differences in knee flexion and extension angles of peak torque between men and women

Background and objections: Anterior cruciate ligament (ACL) injuries are reportedly more prevalent in women compared to men. The aim of the study was to investigate possible differences in knee muscle activation patterns between men (M) and women (W). Methods: Thirty six women with a mean age of 22.0 years (+/- 2.3) and 34 men (22.9 years +/- 2.6) were recruited on a voluntary basis to participate in the study. Bilateral concentric (CON) and eccentric (ECC) bilateral isokinetic testing using a Cybex Norm 7000 was conducted at 60 degrees/s and 180 degrees/s. The angle of peak torque at each velocity was used for analysis. Results: No statistically significant differences (p > 0.05) in angle of peak torque between men and women were observed for CON knee extension and CON knee flexion at either 60 degrees/s or 180 degrees/s. There were statistically significant differences for both the left and right legs (p < 0.05) in ECC knee extension angle of peak torque at 60 degrees/s, with women displaying smaller angles of peak torque (M: 58.0 degrees & 56.5 degrees; W: 52.8 degrees & 51.1 degrees). Significant differences (p < 0.05) were also observed for ECC knee flexion at 60 degrees/s between men and women, with women having larger angles of peak torque (M: 30.4 degrees & 30.7 degrees; W: 38.2 degrees & 40.2 degrees). At 180 degrees/s, the only statistically significant difference (p < 0.05) observed was for the right leg's ECC knee flexion, where the angle of peak torque was again larger for women (M: 39.2 degrees; W: 47.1 degrees). Conclusions: The significantly different angles of peak torque for ECC knee flexion and extension in women compared to men, may negatively impact their ability to effectively protect the knee joint during landing and cutting, thus putting their ACL at a greater risk for injury.