Isometric Hip-Rotator Torque Production at Varying Degrees of Hip Flexion

Context: Hip torque production is associated with certain knee injuries. The hip rotators change function depending on hip angle. Objective: To compare hip-rotator torque production between 3 angles of hip flexion, limbs, and sexes. Design: Descriptive. Setting: University sports medicine research laboratory. Participants: 15 men and 15 women, 19-39 y. Intervention: Three 6-s maximal isometric contractions of the hip external and internal rotators at 10°, 40°, and 90° of hip flexion on both legs. Main Outcome Measure: Average torque normalized to body mass. Results: Internal-rotation torque was greatest at 90° of hip flexion, followed by 40° of hip flexion and finally 10° of hip flexion. External-rotation torque was not different based on hip flexion. The nondominant leg’s external rotators were stronger than the dominant leg’s, but the reverse was true for internal rotators. Finally, the men had more overall rotator torque. Conclusions: Hip-rotation torque production varies between flexion angle, leg, and sex. Clinicians treating lower extremity problems need to be aware of these differences.