Evaluation of muscle fatigue state by ultrasonic attenuation coefficient

Overtraining under muscle fatigue will greatly increase the risk of injury, therefore objective and accurate assessment of muscle fatigue is of great significance for exercise guidance. Muscle fatigue embodies the reduction of muscle force and the changes in muscle microstructure. The changes in muscle microstructure will affect its acoustic transmission characteristics. In this paper, we study the ultrasonic attenuation coefficient as an indicator for assessing muscle fatigue. Eight healthy young males participated in this experiment, none of them had a history of neuromuscular disease. We collected the B-mode ultrasound images and the corresponding reflected ultrasonic signals of the biceps in the rest, contraction, and fatigue state. The muscle thickness increases to the maximum in the contraction state and decreases in the fatigue state but remains higher than the initial state. The ultrasonic attenuation coefficient of the biceps increases to the maximum in the contraction state and decreases to a lower value in the fatigue state than that in the initial state. The results demonstrated that the variation of attenuation coefficient is a feasible scheme for the assessment of muscle fatigue.