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.
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.
Authors: Mark S Miller; Nicholas G Bedrin; Philip A Ades; Bradley M Palmer; Michael J Toth Journal: Am J Physiol Cell Physiol Date: 2015-01-07 Impact factor: 4.249
Authors: Seung Jun Choi; Carol A Shively; Thomas C Register; Xin Feng; John Stehle; Kevin High; Edward Ip; Stephen B Kritchevsky; Barbara Nicklas; Osvaldo Delbono Journal: J Gerontol A Biol Sci Med Sci Date: 2012-08-24 Impact factor: 6.053
Authors: Marin Jane McBride; Kevin P Foley; Donna M D'Souza; Yujin E Li; Trevor C Lau; Thomas J Hawke; Jonathan D Schertzer Journal: Am J Physiol Endocrinol Metab Date: 2017-05-23 Impact factor: 4.310
Authors: Sarah F Eby; Beth A Cloud; Joline E Brandenburg; Hugo Giambini; Pengfei Song; Shigao Chen; Nathan K LeBrasseur; Kai-Nan An Journal: Clin Biomech (Bristol, Avon) Date: 2014-11-29 Impact factor: 2.063