Muscle capillarization, o2 diffusion distance, and o2 kinetics in
old and young individuals.
Chilibeck, P. D., D. H. Paterson, D. A. Cunningham, A. W. Taylor, and
E. G. Noble.
The Centre for Activity and Ageing, Faculty of Kinesiology, The
University of Western Ontario, London, Ontario, Canada
APStracts 3:0420A, 1996.
The relationships between muscle capillarization, estimated O2
diffusion distance from capillary to mitochondria, and O2 uptake (O2)
kinetics were studied in 11 young (25.9y) and 9 old (66.0y) adults.
O2 kinetics were determined by calculating the time constants ([tau])
for the phase 2 O2 adjustment to and recovery from the average of 12
repeats of a 6 minute, 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 O2 kinetics ([tau]O2-on=44 vs 48s; [tau]O2-off=33 vs 44s, 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 fibre / average
fibre area and the estimates of diffusion distance were significantly
correlated to O2-off kinetics in the young (r=-0.68 to -0.83;
p<0.05). We conclude that: 1) capillarization and O2 kinetics
during exercise of a muscle group accustomed to everyday activity
(ie. walking), are well maintained in old individuals, 2) in the
young, recovery of O2 following exercise is faster with a greater
capillary supply over a given muscle fibre area or shorter O2
diffusion distances.
Received 28 February 1996; accepted in final form 22 August 1996.
APS Manuscript Number A203-6.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 19 September 1996