Gait biomechanics following unilateral hamstring fatigue

Abstract

Hamstring strain injuries (HSIs) are one of the most common non-contact injuries across many sports, costing athletes time in training and competition. HSIs are most often sustained during very high-speed running, typically occuring in the long head of the biceps femoris (BFlh). Athletes with prior HSIs have been found to experience significant changes to their gait biomechanics. Fatigue induced by eccentric muscle contractions presents similarly to HSIs, both accompanied by strength and neuromuscular deficits. This study's overall objective is to examine the short- and long-term effects of unilateral hamstring fatigue in recreationally active college-aged females. This study used a pre-post test design where baseline gait symmetry data was compared to data recorded following a unilateral hamstring fatigue protocol throughout a 48-hour follow-up period. The fatigue protocol consisted of single-leg supine hamstring curls, which preferentially targets the BFlh. The gait symmetry data was collected using wearable accelerometer units during running trials at four different speeds on a treadmill. IMeasureU (IMU) devices were used to measure tibial acceleration and surface electromyography (sEMG) units were used to measure muscle activation in both the BFlh and the medial hamstrings (MH). Step times from the control to the exercised limb and peak tibial acceleration in the exercised limb were reduced, along with an overall decrease in gait symmetry following the fatigue protocol. Gait effects following fatiguing activity were heightened immediately after activity and up to 24 hours-post activity. These findings provide insight into the potential for using wearable technology as a tool for HSI rehabilitation and evaluation. The results from this study along with future studies can be used to create a more detailed timeline of gait variables affected by eccentric exercise-induced fatigue.