Influence of hip and knee positions on gluteus maximus and hamstrings contributions to hip extension torque production

Background Diminished gluteus maximus muscle strength has been proposed to be contributory to various lower-limb injuries. As such, it is of clinical importance to perform hip extensor strength testing in a position that biases torque contribution of the gluteus maximus relative to the other hip extensors (i.e. hamstrings). Objectives To determine the relative torque contributions of the gluteus maximus and hamstring muscles in various hip extensor strength testing positions. Methods 13 Young, healthy participants performed maximum isometric hip extension on a dynamometer in 4 different positions that varied in terms of hip and knee flexion. Surface electromyography (EMG) was used to assess activation of gluteus maximus and hamstrings during the maximum isometric contractions. Normalized EMG data were used as an input to determine individual muscle contribution to hip extension torque production using SIMM modeling software. The gluteus maximus/hamstring torque contribution ratio was compared across the 4 positions using a one-way repeated-measures ANOVA. Results The highest gluteus maximus torque contribution value occurred in positions where the hip was flexed to 45 degrees, while the highest hamstring torque contribution occurred in positions in which the knee was fully extended. The gluteus maximus/hamstring torque contribution ratio was highest at 0 degrees of hip extension and 90 degrees of knee flexion. Conclusion Testing isometric hip extensor strength at 0 degrees of hip extension and 90 degrees of knee flexion should be considered in order to bias torque production of the gluteus maximus relative to the hamstrings.

Automated summary

The study aimed to determine the relative torque contributions of the gluteus maximus and hamstrings in different testing positions. Results showed that the gluteus maximus had the highest torque contribution at 45 degrees of hip flexion, while the hamstrings had the highest contribution at full knee extension. The gluteus maximus/hamstring torque contribution ratio was highest at 0 degrees of hip extension and 90 degrees of knee flexion.