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Power Output and Muscle Myosin Heavy Chain Composition in Young and Elderly Men

2006; Lippincott Williams & Wilkins; Volume: 38; Issue: 9 Linguagem: Inglês

10.1249/01.mss.0000227638.75983.9d

1530-0315

Stephen Pearson, M. Cobbold, Richard W. Orrell, Stephen D. R. Harridge,

Children's Physical and Motor Development

Purpose: Aging is associated with a decline in muscle volume, power output, and the velocity at which peak power (Vopt) occurs. The current study aimed to examine the relationship between lower-limb power output characteristics, muscle myosin heavy chain (MHC) composition, and lean limb volume. Methods: Lower-limb power output during repeated efforts on an inertial sprint cycle and single-leg thrusts on the modified Nottingham power rig was studied in seven young and seven old males in relation to muscle MHC isoform composition of the vastus lateralis. Results: Older subjects produced significantly lower power outputs and Vopt under all conditions (P < 0.01) and had lower proportions of fast MHC isoforms (P< 0.05). Peak power output during cycling was significantly related to lower-limb lean volume (r = 0.92, P < 0.05), whereas Vopt during sprint cycling was closely related to vastus lateralis MHC-II composition (r = 0.80, P < 0.05). Conclusions: These results provide further evidence of the importance of fast myosin isoform composition in the maintenance of dynamic muscle function in later life and particularly for maximal cycling performance.