Muscle architectural characteristics in women aged 20-79 years.

Purpose: The purpose of this study was to investigate the muscle architectural characteristics, i.e., muscle thickness, pennation angle, and fascicle length, in women aged 20-79 yr.

Methods: A total of 224 sedentary healthy women participated in this study. Muscle thickness and pennation angle of the vastus lateralis (VL), medial gastrocnemius (MG), and triceps brachii (TB) muscles were measured by B-mode ultrasonography, and the fascicle length was estimated.

Results: Relative muscle thickness of VL and MG decreased significantly with advanced age (VL: P< 0.01, MG: P< 0.05). In addition, the ratio of muscle thickness of VL to that of MG decreased significantly with advanced age (r = -0.206, P< 0.05). The pennation angle decreased significantly with aging for VL (P< 0.001) but not for MG. For TB, no significant age-related changes in relative muscle thickness or pennation angle were observed. There were no significant correlations between age and relative fascicle length (to limb length) in any of the studied muscles.

Conclusion: These results suggested that the declines in muscle thickness and pennation angle with aging were remarkable in the vastus lateralis muscle and slight in the medial gastrocnemius muscle. For the triceps brachii muscle, the muscle thickness and pennation angle did not decrease with advanced age. Furthermore, no significant age-related changes in relative fascicle length (to limb length) were observed in any of the studied muscles.