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Chest. 2005 Oct;128(4):2025-34.

Exercise training decreases ventilatory requirements and exercise-induced hyperinflation at submaximal intensities in patients with COPD.

Author information

1
Division of Respiratory and Critical Care Physiology and Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Rehabilitation Clinical Trials Center, Torrance, CA 90502, USA. jporszasz@labiomed.org

Abstract

STUDY OBJECTIVES:

We hypothesized that endurance exercise training would reduce the degree of hyperinflation for a given level of exercise and thereby improve submaximal exercise endurance.

METHODS:

Twenty-four patients with COPD (mean FEV(1), 36.4 +/- 8.5% of predicted [+/- SD]) undertook a high-intensity cycle ergometer exercise training program for 45 min, three times a week for 7 weeks. Before and after training, the patients performed both an incremental exercise test to maximum and a constant work rate (CWR) test on a cycle ergometer at 75% of the peak work rate obtained in the pretraining incremental test. Ventilatory variables were measured breath-by-breath, and inspiratory capacity (IC) was measured every 2 min to assess changes in end-expiratory lung volume.

RESULTS:

After training, the increase in peak oxygen uptake was not statistically significant; however, the peak work rate increased by 12.9 +/- 10.3 W (p < 0.01). For the CWR test performed at the same work rate both before and after training, ventilation and breathing frequency (f) were lower after training (average, 1.97 L/min and 3.2 breaths/min, respectively; p < 0.01) and IC was greater (by an average of 133 mL, p < 0.05), signifying decreased hyperinflation. The increase in IC at the point of termination in the shortest CWR test for each individual (defined as isotime) correlated well with both the decreased f (r = 0.63, p = 0.001) and with the increase in CWR exercise endurance (average, 13.1 min, r = 0.46, p = 0.023).

CONCLUSIONS:

Exercise training in patients with severe COPD dramatically improves submaximal exercise endurance. Decreased dynamic hyperinflation may, in part, mediate the improvement in exercise endurance by delaying the attainment of a critically high inspiratory lung volume.

PMID:
16236851
DOI:
10.1378/chest.128.4.2025
[Indexed for MEDLINE]

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