Region-specific myoelectric manifestations of fatigue in human rectus femoris muscle.

INTRODUCTION

Anatomical properties between proximal and other regions within the human rectus femoris (RF) muscle are nonuniform. We aimed to clarify the possible region-specific myoelectric manifestations of fatigue within the RF muscle by using an advanced surface electromyography (SEMG) technique.

METHODS

Nine healthy men performed sustained contractions at 50% of maximal voluntary contraction until exhaustion during isometric knee extension and hip flexion. During these contractions, multi-channel SEMG was recorded from the RF by using 46 electrode pairs which cover most of the superficial area of the muscle.

RESULTS

Fatigue-induced SEMG, i.e., an increase in root mean square and a decrease in median frequency, was not uniform within the muscle during both tasks and was greater in proximal regions.

CONCLUSIONS

Our findings suggest that myoelectric manifestations of fatigue within the human RF muscle are localized, and proximal regions are more fatigable than other regions within this muscle.