Determinants of the exercise endurance capacity in patients with chronic obstructive pulmonary disease - The power-duration relationship

Determinants of the exercise endurance capacity in patients with chronic obstructive pulmonary disease - The power-duration relationship

Author Neder, Jose Alberto Autor UNIFESP Google Scholar
Jones, Paul W. Google Scholar
Nery, Luiz Eduardo Autor UNIFESP Google Scholar
Whipp, Brian J. Google Scholar
Institution Univ London
Universidade Federal de São Paulo (UNIFESP)
Abstract To characterize the determinants of the power-duration (W over dot -t) relationship in patients with chronic obstructive pulmonary disease (COPD), we evaluated 8 nonhypoxemic patients (FEV1 = 1.27 +/- 0.26 L) and 10 healthy controls. After an initial maximum-incremental exercise test on cycle ergometer (peak), the subjects underwent four high-intensity constant-load tests to the limit of tolerance (t), each on different days. The W over dot -t relationship was found to be hyperbolic in both groups. Absolute values of both the critical power asymptote (theta(F)) and the curvature constant (W') were lower in patients than in control subjects. However, when expressed as percentage of peak work rate theta(F) was significantly higher in patients compared with control subjects (81.8 +/- 3.3% versus 67.5 +/- 3.7%, respectively, p < 0.01). There were severe reductions in t in the patients that were consistently associated with higher breathlessness scores and V over dot (E)/MVV ratios. Interestingly, all patients were able to sustain exercise at BF for 20 min despite near-maximum physiological and subjective stresses. We conclude that the reductions of both parameters of the hyperbolic W over dot -t relationship (theta(F) and W') in patients with COPD were due to the ventilatory constraints and their sensory consequences. Importantly, theta(F) separated a sustainable from a nonsustainable exercise-intensity domain: this parameter consistently occurred closer to peak work rate in patients than the healthy control subjects.
Language English
Date 2000-08-01
Published in American Journal Of Respiratory And Critical Care Medicine. New York: Amer Lung Assoc, v. 162, n. 2, p. 497-504, 2000.
ISSN 1073-449X (Sherpa/Romeo, impact factor)
Publisher Amer Lung Assoc
Extent 497-504
Origin http://dx.doi.org/10.1164/ajrccm.162.2.9907122
Access rights Closed access
Type Article
Web of Science ID WOS:000088829200028
URI http://repositorio.unifesp.br/11600/42379

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