Six-minute walking versus shuttle walking: responsiveness to bronchodilation in chronic obstructive pulmonary disease.

BACKGROUND The responsiveness of the endurance shuttle walk to functional changes following bronchodilation has recently been reported. The current literature suggests that the 6 min walking test (6MWT) is less responsive to bronchodilation than the endurance shuttle walk. AIM To compare bronchodilator-induced changes in exercise performance with the 6MWT and the endurance shuttle walk. METHODS In a randomised, double-blind, placebo-controlled, crossover trial, 14 patients with chronic obstructive pulmonary disease (forced expiratory volume in 1 s (FEV(1)) 50 (8)% predicted) completed two 6MWTs and two endurance shuttle walks, each preceded by nebulised placebo or 500 microg ipratropium bromide. Cardiorespiratory parameters were monitored during each walking test with a portable telemetric gas analyser. Quadriceps twitch force was measured by magnetic stimulation of the femoral nerve before and after each walking test. RESULTS The 6 min walking distance did not change significantly after bronchodilation despite a significant increase in FEV(1) of 0.18 (0.09) litres (p<0.001). A similar change in FEV(1) (0.18 (0.12) litres, p<0.001) was associated with a significant improvement in the distance walked on the endurance shuttle walk (Deltadistance ipratropium bromide--placebo = 144 (219) m, p = 0.03). Quadriceps muscle fatigue was infrequent (<15% of patients) after both walking tests. CONCLUSION The endurance shuttle walk is more responsive than the 6MWT for detecting changes in exercise performance following bronchodilation.