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Details for article 12 of 19 found articles
| Title: |
Metabolic and respiratory profile of the upper limit for prolonged exercise in man |
| Author: |
Poole, David C. Ward, Susan A. Gardner, Gerald W. Whipp, Brian J. |
| Appeared in: |
Ergonomics |
| Paging: | Volume 31 (1988) nr. 9 pages 1265-1279 |
| Year: |
1988-09-01 |
| Contents: |
For high-intensity cycling, power (P) can be well described as a hyperbolic function of tolerable work duration (t): P=(W'/t) + PLL W' is a constant and PLL is the lower limit (asymptote) for P which is shown to occur at an O2 uptake (V˙O2) lying above the estimated threshold for sustained blood [lactate] increase (ΘIac) but below the maximum V˙O2 (V˙O2max) obtained during incremental cycling. This relation suggests that, above PLL, only a certain amount of work (W') can be accomplished regardless of its rate of performance, with V˙O2 max being attained at fatigue. Hence, PLL defines a point of discontinuity in the V˙O2-P relation for supra-ΘIac exercise. In order to determine the factors responsible for the continued increase in V˙O2 (to the maximum fatiguing value) at power outputs >PLL, we documented the temporal profiles of metabolic (rectal temperature; blood [lactate], [pyruvate], [norepinephrine], [epinephrine]) and respiratory (V˙E; V˙O2; V˙CO2; blood pH, PCO2, [HCO3-]) responses to constant-load cycling in eight healthy males at PLL (24 min) and slightly above PLL (to exhaustion, i.e. < 24 min). V˙O2 manifested a delayed steady state at PLL, despite catecholamine levels and core temperature continuing to increase throughout; blood [lactate] and pH plateaued, however. In contrast, V˙O2 continued to increase slowly for the duration of the exercise > PLL and attained V˙O2max. The response patterns at PLL, and > PLL suggest that the slow phase of the V˙O2 response is best correlated with the temporal profile of blood [lactate], and hence the site and route of metabolism of this variable may play a major role in the V˙O2 kinetics for high-intensity exercise. |
| Publisher: |
Taylor & Francis |
| Source file: |
Elektronische Wetenschappelijke Tijdschriften |
Details for article 12 of 19 found articles
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