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JOURNAL
OF
SPORTS SCIENCE &
MEDICINE
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Research
article
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OXYGEN UPTAKE KINETICS DURING INCREMENTAL- AND DECREMENTAL-RAMP CYCLE ERGOMETRY |
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Fadıl Özyener1,2  ,
Harry B. Rossiter1,3, Susan A. Ward4 and Brian J.
Whipp1,4 |
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1Dept of Physiology, St George's Hospital Medical School, London, United Kingdom; 2Dept of Physiology, Uludag University Medical School, Bursa, Turkey; 3Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom; and 4Human Bio-Energetics Research Centre, Crickhowell, Powys, United Kingdom |
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© Journal of Sports Science and Medicine (2011) 10, 584 - 589 |
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| ABSTRACT | |||
| The pulmonary oxygen uptake (VO2) response to incremental-ramp
cycle ergometry typically demonstrates lagged-linear first-order kinetics
with a slope of ~10-11 ml·min-1·W-1, both above and below the
lactate threshold (ӨL), i.e. there is no discernible VO2 slow
component (or "excess" VO2) above ӨL. We were interested
in determining whether a reverse ramp profile would yield the same response
dynamics. Ten healthy males performed a maximum incremental -ramp (15-30
W·min-1, depending on fitness). On another day, the work rate
(WR) was increased abruptly to the incremental maximum and then decremented
at the same rate of 15-30 W.min-1 (step-decremental ramp). Five
subjects also performed a sub-maximal ramp-decremental test from 90% of ӨL. VO2 was determined breath-by-breath from continuous monitoring
of respired volumes (turbine) and gas concentrations (mass spectrometer).
The incremental-ramp VO2-WR slope was 10.3 ± 0.7 ml·min-1·W-1,
whereas that of the descending limb of the decremental ramp was 14.2 ± 1.1
ml·min-1·W-1 (p < 0.005). The sub-maximal decremental-ramp
slope, however, was only 9. 8 ± 0.9 ml·min-1·W-1: not significantly
different from that of the incremental-ramp. This suggests that the VO2
response in the supra-ӨL domain of incremental-ramp exercise manifest not
actual, but pseudo, first-order kinetics. Key words: Oxygen uptake-work rate gain, incremental-ramp exercise, decremental-ramp exercise, system linearity. |
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