Affiliation:
1. The Centre for Activity and Ageing, Faculty of Kinesiology, and Department of Physiology, The University of Western Ontario, London, Ontario, Canada N6A 3K7
Abstract
Chilibeck, P. D., D. H. Paterson, D. A. Cunningham, A. W. Taylor, and E. G. Noble. Muscle capillarization, O2 diffusion distance, andV˙o 2 kinetics in old and young individuals. J. Appl. Physiol.82(1): 63–69, 1997.—The relationships between muscle capillarization, estimated O2diffusion distance from capillary to mitochondria, and O2 uptake (V˙o 2) kinetics were studied in 11 young (mean age, 25.9 yr) and 9 old (mean age, 66.0 yr) adults. V˙o 2kinetics were determined by calculating the time constants (τ) for the phase 2V˙o 2 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 similarV˙o 2 kinetics (τV˙o 2-on = 44 vs. 48 s; τV˙o 2-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 toV˙o 2-off kinetics in the young ( r = −0.68 to −0.83; P < 0.05). We conclude that 1) capillarization andV˙o 2 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 ofV˙o 2 after exercise is faster, with a greater capillary supply over a given muscle fiber area or shorter O2 diffusion distances.
Publisher
American Physiological Society
Subject
Physiology (medical),Physiology
Cited by
85 articles.
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