Exercise training decreases ventilatory requirements and exercise-induced hyperinflation at submaximal intensities in patients with COPD.
OBJECTIVE
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.
Porszasz
Janos
J
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
Emtner
Margareta
M
Goto
Shinichi
S
Somfay
Attila
A
Whipp
Brian J
BJ
Casaburi
Richard
R
D000368:Aged; D015444:Exercise; D005080:Exercise Test; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D010809:Physical Fitness; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology / Q000534:rehabilitation*; D012115:Residual Volume; D014797:Vital Capacity