[Comparison of a shuttle walking test with an exertion test with cycloergometer in patients with COPD]

To validate a shuttle walking test in a group of patients with COPD, comparing responses to those produced by a conventional stress test limited by symptoms on the cycle ergometer, and to analyze the relation between the shuttle walking test and maximal effort parameters. We enrolled 20 patients with COPD, mean age 60 years (SD 7), FEV1/46.6% (SD 19.2) of theoretical value and FEV1/FVC% 47.3% (SD 11.2). All the patients underwent a maximal effort test on the cycle ergometer, determination of initial dyspnea by applying Mahler's baseline dyspnea index, and a quality of life questionnaire specific to COPD the Chronic Respiratory Disease Questionnaire). To compare the responses of patients to the two tests, we analyzed heart rate, dyspnea and lactic acid at the end of each test. To see the relations between the two tests, we examined distance walked and maximal effort parameters. The relation between the walking test and lung function parameters at rest, initial dyspnea and quality of life were also analyzed. No statistically significant differences were found for heart rate [128.2 (SD 19.8) versus 131.6 (SD 12.9)], dyspnea 17.1 (SD 1.78) versus 7.24 (SD 2.64)] or lactic acid [5.24 (SD 2.34) versus 6.19 (SD 2.12)] at the end of the tests. Distance covered on the shuttle walking test correlated significantly with V'O2ml/min/Kgmax (r = 0.71), as well as with the remaining parameters of maximal effort. There was only a slight relation between lung function at rest and quality of life. The COPD patient's cardiovascular, metabolic and subjective responses to the shuttle walking test are similar to those of the cycle ergometer test, and oxygen consumption is significantly correlated. The shuttle walking test gives a valid estimate of the functional capacity of COPD patients.