Aging of skeletal muscle: a 12-yr longitudinal study

J Appl Physiol (1985). 2000 Apr;88(4):1321-6. doi: 10.1152/jappl.2000.88.4.1321.

Abstract

The present study examines age-related changes in skeletal muscle size and function after 12 yr. Twelve healthy sedentary men were studied in 1985-86 (T1) and nine (initial mean age 65.4 +/- 4.2 yr) were reevaluated in 1997-98 (T2). Isokinetic muscle strength of the knee and elbow extensors and flexors showed losses (P < 0.05) ranging from 20 to 30% at slow and fast angular velocities. Computerized tomography (n = 7) showed reductions (P < 0.05) in the cross-sectional area (CSA) of the thigh (12.5%), all thigh muscles (14.7%), quadriceps femoris muscle (16.1%), and flexor muscles (14. 9%). Analysis of covariance showed that strength at T1 and changes in CSA were independent predictors of strength at T2. Muscle biopsies taken from vastus lateralis muscles (n = 6) showed a reduction in percentage of type I fibers (T1 = 60% vs. T2 = 42%) with no change in mean area in either fiber type. The capillary-to-fiber ratio was significantly lower at T2 (1.39 vs. 1. 08; P = 0.043). Our observations suggest that a quantitative loss in muscle CSA is a major contributor to the decrease in muscle strength seen with advancing age and, together with muscle strength at T1, accounts for 90% of the variability in strength at T2.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Aged
  • Aging / physiology*
  • Capillaries / growth & development
  • Capillaries / physiology
  • Elbow Joint / physiology
  • Humans
  • Isometric Contraction
  • Knee Joint / physiology
  • Longitudinal Studies
  • Male
  • Middle Aged
  • Muscle Development
  • Muscle Fibers, Skeletal / cytology
  • Muscle Fibers, Skeletal / physiology
  • Muscle, Skeletal / blood supply
  • Muscle, Skeletal / growth & development
  • Muscle, Skeletal / physiology*
  • Time Factors
  • Tomography, X-Ray Computed