Males and females respond similarly to walking with a standardized, heavy load

Abstract

Females in the military sustain a higher incidence of lower extremity injuries compared to males. Previous investigations of gender differences during load carriage used loads normalized to body mass; as a result of anthropometric and strength differences between genders, this may partially normalize to strength, masking gender or size differences in response to load. We compared gait kinetics and kinematics between genders based on a standardized load, instead of loads relative to body mass. 11 males and 11 females walked at 1.5 m/s over level ground with a 22 kg rucksack using three load conditions: unloaded, low-back placement, and mid-back placement. We found a gender by load interaction for average trunk position (p < 0.05). Stride length decreased 1.3% in loaded vs. unloaded walking. Loaded walking increased knee extensor (65%) and ankle plantarflexor torque (23%, all p < 0.0001), but not hip extensor torque (p > 0.05) compared to unloaded walking. The lack of gender differences may indicate that females do not adapt gait mechanics to account for smaller stature and lesser absolute strength compared to males, which may contribute to the high injury rate in female military recruits.