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Exercise Training Decreases Ventilatory Requirements and Exercise-Induced Hyperinflation at Submaximal Intensities in Patients With COPD^*

^* From the Division of Respiratory and Critical Care Physiology and Medicine (Drs. Porszasz, Whipp, and Casaburi), Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Rehabilitation Clinical Trials Center, Torrance, CA; Department of Neuroscience (Dr. Emtner), Section of Physiotherapy, Uppsala University, Uppsala, Sweden; First Department of Medicine (Dr. Goto), Tokyo Women’s Medical University School of Medicine, Tokyo, Japan; and Department of Pulmonology (Dr. Somfay), Faculty of Medicine, Szeged University, Deszk, Hungary.

Correspondence to: Janos Porszasz, MD, PhD, Division of Respiratory and Critical Care Physiology and Medicine. Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Rehabilitation Clinical Trials Center, 1124 W Carson St, Bldg J4. Campus mailbox 405, Torrance, CA, 90502; e-mail: jporszasz{at}labiomed.org

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 FEV₁, 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.

Key Words: dynamic hyperinflation • endurance • exercise training • rehabilitation • respiratory rate

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				T. E. Dolmage and R. S. Goldstein Effects of One-Legged Exercise Training of Patients With COPD Chest, February 1, 2008; 133(2): 370 - 376. [Abstract] [Full Text] [PDF]

				R Casaburi Combination therapy for exercise intolerance in COPD. Thorax, July 1, 2006; 61(7): 551 - 552. [Full Text] [PDF]

				R. Casaburi and J. Porszasz Reduction of hyperinflation by pharmacologic and other interventions. Proceedings of the ATS, January 1, 2006; 3(2): 185 - 189. [Abstract] [Full Text] [PDF]