Muscle capillarization, O2 diffusion distance, and V̇O2 kinetics in old and young individuals

P. D. Chilibeck, D. H. Paterson, D. A. Cunningham, A. W. Taylor, E. G. Noble

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The relationships between muscle capillarization, estimated O2 diffusion distance from capillary to mitochondria, and O2 uptake (V̇O2) kinetics were studied in 11 young (mean age, 25.9 yr) and 9 old (mean age, 66.0 yr) adults. V̇O2 kinetics were determined by calculating the time constants (τ) for the phase 2 V̇O2 adjustment to and recovery from the average of 12 repeats of a 6-min, moderate-intensity plantar flexion exercise. Muscle capillarization was determined from cross sections of biopsy material taken from lateral gastrocnemius. Young and old groups had similar V̇O2 kinetics (τV̇O-on= 44 vs. 48 s; τV̇O2-off = 33 vs. 44 s, for young and old, respectively), muscle capillarization, and estimated O2 diffusion distances. Muscle capillarization, expressed as capillary density or average number of capillary contacts per fiber/average fiber area, and the estimates of diffusion distance were significantly correlated to V̇O2-off kinetics in the young (r = -0.68 to -0.83; P < 0.05). We conclude that 1) capillarization and V̇O2 kinetics during exercise of a muscle group accustomed to everyday activity (e.g., walking) are well maintained in old individuals, and 2) in the young, recovery of V̇O2 after exercise is faster, with a greater capillary supply over a given muscle fiber area or shorter O2 diffusion distances.

Original languageEnglish
Pages (from-to)63-69
Number of pages7
JournalJournal of Applied Physiology
Issue number1
Publication statusPublished - Jan 1997



  • aging
  • lateral gastrocnemius
  • plantar flexion

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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