Hip Adduction during Running: Influence of Sex, Hip Abductor Strength and Activation, and Pelvis and Femur Morphology

Purpose: To examine the influence of hip abductor strength, neuromuscular activation, and pelvis and femur morphology in contributing to sex differences in hip adduction during running. In addition, we sought to determine the best predictors of hip adduction during running for both men and women. Methods: Fifteen female runners and 14 male runners underwent strength testing, instrumented overground running (e.g., kinematics and muscle activation), and computed tomography scanning of pelvis and femur. Morphologicmeasurements included bilateral hip width to femur length ratio, acetabulum abduction, acetabulum anteversion, femoral anteversion, and femoral neck-shaft angles. Sex differences for all variables were examined using independent t tests. Linear regression was used to assess the ability of each independent variable of interest to predict peak hip adduction during the late swing and stance phase of running. Results: Compared with men, women exhibited significantly greater peak hip adduction during both late swing (8.5 degrees +/- 2.6 degrees vs 6.2 degrees +/- 2.8 degrees, P = 0.04) and stance phases of running (13.4 degrees +/- 4.2 degrees vs 10.0 degrees +/- 3.2 degrees, P = 0.02). In addition, women exhibited significantly lower hip abductor strength (1.8 +/- 0.3 vs 2.0 +/- 0.3 N.m.kg(-1), P = 0.04), greater femoral neck-shaft angles (134.1 degrees +/- 5.0 degrees vs 129.9 degrees +/- 4.1 degrees, P = 0.01), and greater hip width to femur length ratios than men (0.44 +/- 0.02 vs 0.42 +/- 0.03, P = 0.03). Femoral anteversion was the only significant predictor of peak hip adduction during late swing (r = 0.36, P = 0.05) and stance (r = 0.41, P = 0.03). Conclusions: Our findings highlight the contribution of femur morphology as opposed to hip abductor strength and activation in contributing to hip adduction during running.

Automated summary

Sex differences were found in hip adduction during running, with women showing greater angles, lower hip abductor strength, and different femur morphology than men. Femoral anteversion was identified as a significant predictor of hip adduction angle during late swing and stance phases.