[Chronic obstructive pulmonary disease: evaluation of exercise tolerance using three different exercise tests]

The clinical usefulness of simple exercise tests in patients with chronic obstructive pulmonary disease (COPD) continues to give rise to debate. Questions remain about whether these tests assess maximum effort or only exercise tolerance (submaximal effort). To determine the levels of stress reached during the six-minute walking (6MW) test and stair climbing (SC) test and their relation to maximum aerobic capacity, 50 patients with COPD (FEV1 49 +/- 19%) were studied. Data collected included spirometric variables and VO2, heart rate (HR), ventilatory response and dyspnea during the progressive effort ergometric cycle (PEEC) test. Two 6MW and SC tests were completed on two separate days, with distance, number of steps, HR and dyspnea recorded. HR was higher during the PEEC test. Among the simple tests, SC caused a faster HR than did the 6MW test. Likewise, a significant linear relation was observed between VO2/kgpeak during the 6MW test (r2 = 0.27; p < 0.05) and the SC test (r2 = 0.33; p < 0.01). We therefore conclude that exercise tolerance in patients with COPD can be evaluated using simple stress tests. The SC test is probably the best simple way to determine maximum functional capacity, whereas the 6MW test can be reserved for measurement of exercise tolerance.