期刊
ACTA PHYSIOLOGICA
卷 190, 期 3, 页码 229-241出版社
WILEY
DOI: 10.1111/j.1748-1716.2007.01699.x
关键词
maximum velocity of unloaded shortening; muscle mass; skinned fibres; slack test; specific tension; torque-velocity
类别
资金
- NIAMS NIH HHS [AR045627, AR047318] Funding Source: Medline
- NIA NIH HHS [AG014731] Funding Source: Medline
Aim: The objective of this study is to improve our understanding of the mechanisms underlying the ageing- and gender-related muscle weakness. Methods: Ageing- and gender-related differences in regulation of muscle contraction have been studied in knee-extensor muscles at the whole muscle and single muscle fibre levels in young and old sedentary men and women. In vivo knee-extensor muscle function was measured at slow (30 degrees s(-1)) and faster (180 degrees s(-1)) speeds of movement. Maximum velocity of unloaded shortening (V-0) and maximum force normalized to cross-sectional area (CSA) [specific tension (ST)] were measured in single 'skinned' skeletal muscle fibre segments. Results: Significant ageing- and gender-related differences were observed in muscle torque. A 33-55% ageing-related decline (P < 0.001) in maximum torque was observed irrespective of gender. At the single muscle fibre level, the ageing-related decline in knee-extensor muscle function was accompanied by a 20-28% decline in ST in muscle fibres expressing the type I MyHC isoform in both men and women, and a 29% decline in type IIa muscle fibre CSA, but the decreased fast-twitch fibre size was restricted to the men. Furthermore, in both men and women, V-0 decreased in muscle cells expressing the type I and IIa MyHC isoforms. Conclusion: The present results provide evidence of specific ageing- and gender-related differences in regulation of muscle contraction at the cellular level. It is suggested that these cellular changes have a significant impact on muscle function and the ageing-related motor handicap.
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