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Kinetics of oxygen uptake at the onset of exercise near or above peak oxygen uptake

journal contribution
posted on 2000-05-01, 00:00 authored by R L Hughson, D D O'Leary, Andrew BetikAndrew Betik, H Hebestreit
We tested the hypothesis that kinetics of O2uptake (V̇O2) measured in the transition to exercise near or above peak V̇O2(V̇O(2peak)) would be slower than those for subventilatory threshold exercise. Eight healthy young men exercised at ~57, ~96, and ~125% V̇O(2peak). Data were fit by a two- or three-component exponential model and with a semi-logarithmic transformation that tested the difference between required V̇O2and measured V̇O2. With the exponential model, phase 2 kinetics appeared to be faster at 125% V̇O(2peak) [time constant (τ2) = 16.3 ± 8.8 (SE) s] than at 57% V̇O(2peak) (τ2= 29.4 ± 4.0 S) but were not different from that at 96% V̇O(2peak) exercise (τ2= 22.1 ± 2.1 s). V̇O2at the completion of phase 2 was 77 and 80% V̇O(2peak) in tests predicted to require 96 and 125% V̇O(2peak). When V̇O2kinetics were calculated with the semi-logarithmic model, the estimated τ2at 96% V̇O(2peak) (49.7 ± 5.1 s) and 125% V̇O(2peak) (40.2 ± 5.1 s) were slower than with the exponential model. These results are consistent with our hypothesis and with a model in which the cardiovascular system is compromised during very heavy exercise.

History

Journal

Journal of applied physiology

Volume

88

Issue

5

Pagination

1812 - 1819

Publisher

American Physiological Society

Location

Bethesda, Md.

ISSN

8750-7587

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2000, the American Physiological Society