Gait adaptations during load carrying on level and inclined surfaces

Abstract

The complex human processes involved in balance maintenance and fall prevention during normal locomotion are further complicated by load carrying and/or the presence of slippery floors. The goal of this study was to investigate the effect of carrying loads (2-handed method) on gait biomechanics relevant to slips/falls. Participants walked down surfaces of varying inclinations (0°, 5° and 10°), while ground reaction forces and body/foot motion were recorded. Three load conditions (no load, 2.3 and 6.8 kg) were included. Load carrying was associated with increases in the peak normal ground reaction force and in the rate of the normal loading phase on the leading foot. Shear ground reaction forces were not affected by load carrying. Changes in the ground reaction forces recorded during load carrying led to reduced required coefficient of friction (RCOF) values, a variable used to rate slip potential. This RCOF reduction is partly due to postural adaptations such as increased knee and hip flexion adopted during load carrying. Furthermore, load carrying was accompanied by slower heel contact heel velocity in the direction of motion. Finally, moments generated at the hip and knee joints were significantly biased towards the extensor and flexor direction, respectively.