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- Title
Physiological Correlates of Endurance Time Variability during Constant-Workrate Cycling Exercise in Patients with COPD.
- Authors
Vivodtzev, Isabelle; Gagnon, Philippe; Pepin, Véronique; Saey, Didier; Laviolette, Louis; Brouillard, Cynthia; Maltais, François
- Abstract
Rationale The endurance time (T end) during constant-workrate cycling exercise (CET) is highly variable in COPD. We investigated pulmonary and physiological variables that may contribute to these variations in T end. Methods Ninety-two patients with COPD completed a CET performed at 80% of peak workrate capacity (W peak). Patients were divided into tertiles of T end [Group 1: <4 min; Group 2: 4-6 min; Group 3: >6 min]. Disease severity (FEV1), aerobic fitness (W peak, peak oxygen consumption [VO2peak], ventilatory threshold [VO2VT]), quadriceps strength (MVC), symptom scores at the end of CET and exercise intensity during CET (heart rate at the end of CET to heart rate at peak incremental exercise ratio [HRCET/HR peak]) were analyzed as potential variables influencing T end. Results W peak, VO 2peak, VO2VT, MVC, leg fatigue at end of CET, and HRCET/HR peak were lower in group 1 than in group 2 or 3 (p⩽0.05). VO2VT and leg fatigue at end of CET independently predicted T end in multiple regression analysis (r = 0.50, p = 0.001). Conclusion T end was independently related to the aerobic fitness and to tolerance to leg fatigue at the end of exercise. A large fraction of the variability in T end was not explained by the physiological parameters assessed in the present study. Individualization of exercise intensity during CET should help in reducing variations in T end among patients with COPD.
- Subjects
CYCLING; AEROBIC exercises; FATIGUE (Physiology); SYMPTOMS; REST
- Publication
PLoS ONE, 2011, Vol 6, Issue 2, p1
- ISSN
1932-6203
- Publication type
Article
- DOI
10.1371/journal.pone.0017007