title: Power output and muscle myosin heavy chain composition in young and elderly men.
abstract: OBJECTIVE
  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.
authors.affiliation: Department of Physiology, Royal Free and University College Medical School, University College London, Rowland Hill Street, London,United Kingdom. s.pearson@salford.ac.uk
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Pearson
authors.forename: Matthew
authors.initials: M
authors.lastname: Cobbold
authors.forename: Richard W
authors.initials: RW
authors.lastname: Orrell
authors.forename: Stephen D R
authors.initials: SD
authors.lastname: Harridge
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging; D001642:Bicycling / Q000502:physiology; D006801:Humans; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D018995:Myosin Heavy Chains / Q000032:analysis / Q000737:chemistry*; D052097:Quadriceps Muscle / Q000737:chemistry* / Q000502:physiology
chemical_list: D018995:Myosin Heavy Chains