Effect of aging on region-specific functional role and muscle geometry along human rectus femoris muscle.

INTRODUCTION: We compared the region-specific neuromuscular activation and muscle morphology along the rectus femoris (RF) muscle between young and elderly.

METHODS: Ratios of surface electromyography amplitude between hip flexion and knee extension (HF/KE) were compared among regions along the muscle for 9 young and 9 elderly men. Muscle thickness was also compared among the regions.

RESULTS: HF/KE in the proximal region was significantly greater than in the middle and distal regions for both the young and elderly (P < 0.05). However, a significant difference in HF/KE between the middle and distal regions was found in the young (P < 0.05), but not in the elderly (P > 0.05). A difference in the region-specific muscle thickness was observed between the young and elderly.

CONCLUSION: These findings suggest that functional role and muscle morphology are regionally affected by aging along the RF muscle. Muscle Nerve 56: 982-986, 2017.