Effects of prior heavy exercise on phase II pulmonary oxygen uptake kinetics during heavy exercise.
We tested the hypothesis that heavy-exercise phase II oxygen uptake (VO(2)) kinetics could be speeded by prior heavy exercise. Ten subjects performed four protocols involving 6-min exercise bouts on a cycle ergometer separated by 6 min of recovery: 1) moderate followed by moderate exercise; 2) moderate followed by heavy exercise; 3) heavy followed by moderate exercise; and 4) heavy followed by heavy exercise. The VO(2) responses were modeled using two (moderate exercise) or three (heavy exercise) independent exponential terms. Neither moderate- nor heavy-intensity exercise had an effect on the VO(2) kinetic response to subsequent moderate exercise. Although heavy-intensity exercise significantly reduced the mean response time in the second heavy exercise bout (from 65.2 +/- 4.1 to 47.0 +/- 3.1 s; P < 0.05), it had no significant effect on either the amplitude or the time constant (from 23.9 +/- 1.9 to 25.3 +/- 2.9 s) of the VO(2) response in phase II. Instead, this "speeding" was due to a significant reduction in the amplitude of the VO(2) slow component. These results suggest phase II VO(2) kinetics are not speeded by prior heavy exercise.
Burnley
M
M
Chelsea School Research Centre, University of Brighton, Eastbourne, East Sussex, BN20 7SP, United Kingdom. M.Burnley@bton.ac.uk
Jones
A M
AM
Carter
H
H
Doust
J H
JH
D000328:Adult; D000818:Animals; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D006801:Humans; D007700:Kinetics; D007773:Lactates / Q000097:blood; D008168:Lung / Q000502:physiology*; D008297:Male; D010101:Oxygen Consumption; D005082:Physical Exertion / Q000502:physiology*; D012044:Regression Analysis; D012146:Rest; D013997:Time Factors
D007773:Lactates