A comparison of cardiopulmonary exercise test and 6 minute walking test in determination of exercise capacity in chronic obstructive pulmonary disease.

ABSTRACT

INTRODUCTION: This study aimed to determine the relationship of 6 minute walking test (6MWT) and cardiopulmonary exercise test (CPET) with each other and with the measures of lung functions in patients with chronic obstructive pulmonary disease (COPD). MATERIALS AND METHODS: Pulmonary function tests, 6MWT, and CPET were performed in 36 (35 males, 1 female) patients with moderate and severe COPD. RESULTS: Maximum oxygen uptake was significantly correlated with 6 minute walking distance. Both exercise tests were correlated with pulmonary function tests. However, maximum exercise capacity was more closely correlated with measures of lung function than 6MWT. Both tests were significantly correlated with static lung volumes. Inspiratory capacity (IC) was significantly correlated with 6MWT and CPET parameters. CPET was significantly correlated with diffusion capacity and maximal inspiratory pressure. Airway conductance and resistance tests showed no correlation with the exercise tests. CONCLUSION: 6MWT is a simple and valuable test to determine the exercise capacity of COPD patients. Both 6MWT and CPET are correlated with ventilatory impairment determined by the lung function tests, particularly FEV1, maximum voluntary ventilation (MVV), and IC. However, CPET is an exercise test that more accurately evaluates and provides more detailed information about hyperinflation and respiratory musce strength than 6MWT does.