CHRONIC OBSTRUCTIVE PULMONARY DISEASE

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

Véronique Pepin, Julie Brodeur, Yves Lacasse, Julie Milot, Pierre LeBlanc, François Whittom, François Maltais

Centre de recherche, Hôpital Laval, Institut Universitaire de Cardiologie et de Pneumologie de l’Université Laval, Québec, Canada

Correspondence to:
Dr François Maltais
Centre de Pneumologie, Hôpital Laval, 2725 Chemin Ste-Foy, Ste-Foy, Québec, G1V 4G5, Canada; francois.maltais{at}med.ulaval.ca

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 (FEV₁) 50 (8)% predicted) completed two 6MWTs and two endurance shuttle walks, each preceded by nebulised placebo or 500 µg 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 FEV₁ of 0.18 (0.09) litres (p<0.001). A similar change in FEV₁ (0.18 (0.12) litres, p<0.001) was associated with a significant improvement in the distance walked on the endurance shuttle walk (distance 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.

Abbreviations: COPD, chronic obstructive pulmonary disease; FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity; 6MWD, 6 min walking distance; 6MWT, 6 min walking test; MVV, maximum voluntary ventilation; SpO₂, oxygen saturation; CO₂, carbon dioxide production; E, minute ventilation; O₂, oxygen consumption

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