Gender differences in resistance-training-induced myofiber hypertrophy among older adults.

Academic Article

Abstract

  • We tested the hypothesis that older men (n = 9, 69 +/- 2 years) would experience greater resistance-training-induced myofiber hypertrophy than older women (n = 5, 66 +/- 1 years) following knee extensor training 3 days per week at 65-80% of one-repetition maximum for 26 weeks. Vastus lateralis biopsies were analyzed for myofiber areas, myosin heavy chain isoform distribution, and levels of mRNA for insulin-like growth factor 1 (IGF-1), IGFR1, and myogenin. Gender x Training interactions (p <.05) indicate greater myofiber hypertrophy for all three primary fiber types (I, IIa, IIx) and enhanced one-repetition maximum strength gain in men compared with women (p <.05). Covarying for serum IGF-1, dehydroepiandrosterone sulfate, or each muscle mRNA did not negate these interactions. In both genders, type IIx myofiber area distribution and myosin heavy chain type IIx distribution decreased with a concomitant increase in type IIa myofiber area distribution (p <.05). In summary, gender differences in load-induced myofiber hypertrophy among older adults cannot be explained by levels of circulating IGF-1 or dehydroepiandrosterone sulfate, or by expression of the myogenic transcripts examined.
  • Published In

    Keywords

  • Non-programmatic, Aged, Analysis of Variance, Body Composition, Body Mass Index, Cohort Studies, Exercise, Female, Humans, Immunohistochemistry, Insulin-Like Growth Factor I, Male, Middle Aged, Muscle Fibers, Skeletal, Muscle, Skeletal, Myogenin, Physical Education and Training, Reference Values, Sensitivity and Specificity, Sex Factors
  • Author List

  • Bamman MM; Hill VJ; Adams GR; Haddad F; Wetzstein CJ; Gower BA; Ahmed A; Hunter GR
  • Start Page

  • 108
  • End Page

  • 116
  • Volume

  • 58
  • Issue

  • 2