Effects of two types of training on pulmonary and cardiac responses to moderate exercise in patients with COPD

The effects of two 8-week programmes of exercise reconditioning on the time constants (tau) of the pulmonary gas exchange, ventilatory and heart rate responses to moderate intensity exercise in patients with chronic obstructi ve pulmonary disease (COPD) were studied. Thirty-five subjects (mean+/-SD 64+/-5 yrs; forced expiratory volume in one second (FEV1) 1.09+/-0.17 L; 41+/-6.2% predicted) were randomly assigned e ither to supervised (s) training on a treadmill, 4 days.week(-1) (group S; n=21) or self-monitored (SM) walking 3 or 4 km in 1 h 4 days.week(-1) (grou p SM; n=20). The different levels of supervision resulted in a different es timated intensity of training (35+/-10 W in the SM group and 70+/-22 W in t he S group). The kinetics were evaluated with a constant-load exercise test on a cycle-ergometer at a work rate corresponding to 80% the highest oxyge n consumption (V'O-2) that can be achieved without blood lactic acidosis(V' O-2,I.AT) or 50% of V'O-2,max, if maximum oxygen consumption V'O-2,LAT was not found. Mean endurance time at a work rate equivalent to 70% of the pretraining V'O -2,max increased by 493+/-281 s in the S group and 254+/-283 s in the SM gr oup (p<0.001). Mean tau V'O-2 decreased from 83+/-17 s to 67+/-11 s (p<0.00 01) in the S group and from 84+/-12 to 79+/-16 (p=0.04) in the SM group. Me an tau for carbon dioxide output minute ventilation and heart rate were als o speeded after training, again more markedly in the S group. In the S grou p there was a significant correlation between the decrease in tau V'O-2 and the increase in endurance time (r=-0.56, SEM=0.21). It is concluded that training speeds the kinetic response of oxygen consump tion, carbon dioxide production, minute ventilation and heart rate to moder ate exercise and that the effect is greater after supervised, more intense training.