Stepping down during continuous gait is a common functional activity. Muscle fatigue has an adverse effect on gait parameters, which may contribute to an increased risk of falling. The purpose of this pilot work is to evaluate the role of ankle evetor fatigue on lower limb biomechanics during stepping down in continuous gait. Six healthy subjects (3M/3F, 27.0±2.3 years, 1.69±0.08m, 63.88±8.49kg) were recruited for the study. A custom 8.5m long walkway was built with a 15cm step to simulate a street curb. Only kinematic, kinetic and EMG data from the leg used to step down (leading leg) were reported. Subjects were instructed to walk barefoot at self-selected speed on the elevated walkway, step down onto the lower walkway, and keep walking until the end of the platform. The evertor muscles were fatigued using an isokinetic dynamometer. Immediately after the fatigue protocol, subjects were asked to perform the step-down task in the same manner as the pre-fatigue trials. Due to the nature of the study only descriptive statistics were reported. The fatigue protocol generated a 5-8% decrease in activation of the peroneals, tibialis anterior and medial gastrocnemius muscles. Following the fatigue protocol, a decrease of dorsiflexion moment was observed after touchdown. Additionally, there was a decrease of the peak of negative power suggesting that less energy was absorbed at the ankle. It appears that the isokinetic evertor fatigue altered muscle activation and may change the biomechanics of stepping down to accommodate for the decreased muscle activity.
Listed In: Biomechanics, Gait, Previous Winners