Affiliation:
1. Department of Nuclear Medicine, Lawson Research Institute, St. Joseph's Health Centre, London, Ontario, Canada.
Abstract
The purpose of this study is to directly compare the dynamic responses of phosphocreatine (PCr) and P(i) to those oxygen uptake (VO2) measured at the lung during transitions to and from moderate-intensity exercise. Changes in PCr and P(i) were measured by 31P-nuclear magnetic resonance spectroscopy, and changes in VO2 were measured breath by breath by mass spectroscopy during transitions to and from moderate-intensity square-wave ankle plantar flexion exercise in 11 subjects (7 men and 4 women; mean age 27 yr). Three repeated transitions were averaged for improvement in signal-to-noise ratio of phosphate data, and 12 transitions were averaged for VO2 measurements. Averaged transitions were fit with a monoexponential curve for determination of the time constant (tau) of the responses. Mean tau values for on transients of PCr, P(i), and phrase 2 VO2 were 47.0, 57.7, and 44.5 s, respectively, whereas means tau values for off transients were 44.8, 42.1, and 33.4 s, respectively. There were no significant differences between tau values for phosphate- and VO2-measured transients or on and off transients. The similarity of on and off kinetics supports linear first-order respiratory control models. Measurement of phase 2 pulmonary VO2 kinetics to and from moderate-intensity small-muscle-mass exercise reflect muscle phosphate kinetics (and muscle oxygen consumption).
Publisher
American Physiological Society
Subject
Physiology (medical),Physiology
Cited by
100 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献