Dynamic responses of oxygen uptake at the onset and end of moderate and heavy exercise in trained subjects
(Dynamische Reaktionen der O2-Aufnahme zu Beginn und am Ende mittlerer und schwerer Belastung bei Trainierten)
Inconsistencies about dynamic asymmetry between the on- and off-transient responses in VO2 are found in the literature. Therefore the purpose of this study was to examine VO2 on- and off-transients during moderate- and heavy-intensity cycling exercise in trained subjects. Ten men underwent an initial incremental test for the estimation of ventilatory threshold (VT) and, on different days, two bouts of square-wave exercise at moderate (<VT) and heavy (>VT) intensities. VO2 kinetics in exercise and recovery were better described by a single exponential model (<VT), or by a double exponential with two time delays (>VT). For moderate exercise, we found a symmetry of VO2 kinetics between the on- and off-transients (i.e., fundamental component), consistent with a system manifesting linear control dynamics. For heavy exercise, a slow component superimposed on the fundamental phase was expressed in both the exercise and recovery, with similar parameter estimates. But the on-transient values of the time constant were appreciably faster than the associated off-transient, and independent of the work rate imposed (<VT and >VT). Our results do not support a dynamically linear system model of VO2 during cycling exercise in the heavy-intensity domain.
© Copyright 2004 Canadian Journal of Applied Physiology. Human Kinetics. Alle Rechte vorbehalten.
Schlagworte: | O2-Aufnahme Sportphysiologie |
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Notationen: | Biowissenschaften und Sportmedizin |
DOI: | 10.1139/h04-003 |
Veröffentlicht in: | Canadian Journal of Applied Physiology |
Veröffentlicht: |
2004
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Jahrgang: | 29 |
Heft: | 1 |
Seiten: | 32-44 |
Dokumentenarten: | Artikel |
Sprache: | Englisch |
Level: | hoch |