Six-Minute Walking Versus Shuttle Walking: Responsiveness to Bronchodilation in Chronic Obstructive Pulmonary Disease

Abstract

Rationale: The responsiveness of the endurance shuttle walk to functional changes following bronchodilation was recently demonstrated, while the current literature suggests that the six-minute walking test is less responsive in that setting.

Objective: To compare bronchodilator-induced changes in exercise performance between the 6-minute walking test and the endurance shuttle walk.

Methods: In a randomised, double-blind, placebo- controlled and crossover trial, 14 patients with chronic obstructive pulmonary disease (FEV1: 50 (8)% predicted) completed two 6-minute walking tests and two endurance shuttle walks, each preceded by the nebulization of either a placebo or 500 μg of ipratropium bromide. Cardiorespiratory parameters were monitored during each walking test with a portable telemetric gas analyser. Quadriceps twitch force was measured with magnetic stimulation of the femoral nerve before and after each walking test.

Results: Six-minute walking distance did not change significantly following bronchodilation despite a significant increase in FEV1 (0.18 (0.09)L, p < 0.001). A similar change in FEV1 (0.18 (0.12)L, p < 0.001) was associated with a significant improvement in the distance walked on the endurance shuttle walk (Δdistance ipratropium bromide-placebo: 144 (219) meters, 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 6-minute walking test to detect changes in exercise performance following bronchodilation.