Pulmonary O2 uptake kinetics as a determinant of high-intensity exercise tolerance in humans
| Autor: | B. J. Whipp, Scott R. Murgatroyd, Susan A. Ward, Carrie Ferguson, Harry B. Rossiter |
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| Rok vydání: | 2011 |
| Předmět: |
Adult
Male Physiology Curvature Models Biological Young Adult Oxygen Consumption Physiology (medical) Humans Lactic Acid Exercise Lung A determinant Physics Analysis of Variance Exercise Tolerance Pulmonary Gas Exchange High intensity Mathematical analysis Uptake kinetics Adaptation Physiological Bicycling Hyperbola Power (physics) Oxygen Kinetics England Exercise Test Linear Models Asymptote Constant (mathematics) |
| Zdroj: | Journal of Applied Physiology. 110:1598-1606 |
| ISSN: | 1522-1601 8750-7587 |
| DOI: | 10.1152/japplphysiol.01092.2010 |
| Popis: | Tolerance to high-intensity constant-power (P) exercise is well described by a hyperbola with two parameters: a curvature constant (W′) and power asymptote termed “critical power” (CP). Since the ability to sustain exercise is closely related to the ability to meet the ATP demand in a steady state, we reasoned that pulmonary O2 uptake (V̇o2) kinetics would relate to the P-tolerable duration (tlim) parameters. We hypothesized that 1) the fundamental time constant (τV̇o2) would relate inversely to CP; and 2) the slow-component magnitude (ΔV̇o2sc) would relate directly to W′. Fourteen healthy men performed cycle ergometry protocols to the limit of tolerance: 1) an incremental ramp test; 2) a series of constant-P tests to determine V̇o2max, CP, and W′; and 3) repeated constant-P tests (WR6) normalized to a 6 min tlim for τV̇o2 and ΔV̇o2sc estimation. The WR6 tlim averaged 365 ± 16 s, and V̇o2max (4.18 ± 0.49 l/min) was achieved in every case. CP (range: 171–294 W) was inversely correlated with τV̇o2 (18–38 s; R2 = 0.90), and W′ (12.8–29.9 kJ) was directly correlated with ΔV̇o2sc (0.42–0.96 l/min; R2 = 0.76). These findings support the notions that 1) rapid V̇o2 adaptation at exercise onset allows a steady state to be achieved at higher work rates compared with when V̇o2 kinetics are slower; and 2) exercise exceeding this limit initiates a “fatigue cascade” linking W′ to a progressive increase in the O2 cost of power production (V̇o2sc), which, if continued, results in attainment of V̇o2max and exercise intolerance. Collectively, these data implicate V̇o2 kinetics as a key determinant of high-intensity exercise tolerance in humans. |
| Databáze: | OpenAIRE |
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