INTENSITY OF TRAINING AND PHYSIOLOGICAL ADAPTATION IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY-DISEASE

The applicability of high-intensity training and the possibility of in ducing physiologic adaptation to training are still uncertain in patie nts with severe chronic obstructive pulmonary disease (COPD). The purp oses of this study were to evaluate the proportion of patients with mo derate to severe COPD in whom high-intensity exercise training (30-min exercise session at 80% of baseline maximal power output [Wmax]) is f easible, and the response to training in these patients. We also sough t to evaluate the possible influence of disease severity on the traini ng intensity achieved and on the development of physiologic adaptation following endurance training. Forty-two patients with COPD (age = 66 +/- 7 yr, FEV(1) = 38 +/- 13% predicted, [mean +/- SD]) were evaluated at baseline and after a 12-wk endurance training program. Each evalua tion included a stepwise exercise test on an ergocycle up to the indiv idual maximal capacity during which minute ventilation (VE), oxygen co nsumption (VO2), carbon dioxide production (VCO2), and arterial lactic acid concentrations were measured. The training consisted of 25 to 30 -min exercise sessions on a calibrated ergocycle three times a week, w ith a target training intensity at 80% of Wmax. The training intensity was adjusted with the objective of reaching the target intensity, but also to ensure that the cycling exercise could be maintained for the specified duration. The training intensity sustained for the duration of each exercise session averaged 24.5 +/- 12.6, 51.7 +/- 17.4, 63.8 /- 22.4, and 60.4 +/- 22.7% of Wmax at Weeks 2, 4, 10, and 12, respect ively. High-intensity training was achieved in zero, three, five, and five patients at Weeks 2, 4, 10, and 12, respectively. A significant i ncrease in VO(2)max and Wmax occurred with training (p < 0.0002). This improvement in exercise capacity was accompanied by a 6% and 17% redu ction in VE and in arterial lactic acid concentration for a given work rate, respectively (p < 0.0001), suggesting that physiologic adaptati on to training occurred. The intensity of training achieved, in % Wmax , was not influenced by the initial VO(2)max, age, or FEV(1). The effe cts of training were compared in patients with an FEV(1) greater than or equal to 40% or < 40% predicted. Percent changes in VO(2)max, Wmax, and VE, were significant and of similar magnitude for both groups, wh ereas the decrease in arterial lactic acid for a given work rate reach ed statistical significance only in those patients with an FEV(1) grea ter than or equal to 40% predicted. We conclude that although most pat ients were unable to achieve high-intensity training as defined in thi s study, significant improvement in their exercise capacity was obtain ed and physiologic adaptation to endurance training occurred. The trai ning intensity expressed as a percent of the individual maximum exerci se capacity, and the relative effectiveness of training, were not infl uenced by the severity of airflow obstruction.