Assessment of low back muscle fatigue during normal gait

Development of low back muscle fatigue has been evaluated by analyzing electromyography (EMG) measured during isometric back extension exercises which cannot be easily administered in non-laboratory settings. The objective of this study was to explore whether the changes in muscle activation pattern induced by muscle fatigue could be identified during normal walking, which can be easily done in daily life. Nineteen subjects participated in an experiment and conducted normal walking trials on a treadmill with a fatigue generating Biering-Sorensen test in between. Eight EMG sensors were bilaterally attached to back and abdominal muscles. Muscle activation levels and integrated EMG of the walking trials were compared between before and after the fatigue development. In result, it was found that the EMG amplitudes and the integrated EMG of the lumbar erector spinae muscles were increased significantly after the fatigue development. Results of this study suggest that muscle fatigue development could be monitored in a daily activity and it may lead to the development of wearable health monitoring systems with surface EMG sensors.