Background: Walking is a familiar daily activity that is generally limited by breathlessness, whereas cycling is an uncommon physical effort typically limited by leg discomfort. The hypothesis was that patients with COPD would exhibit greater improvements in exercise endurance and relief of breathlessness with bronchodilator therapy during treadmill walking compared with cycling.
Methods: In this randomized, 2 x 2, double-blind, placebo-controlled, crossover trial, 20 patients with COPD (age, 64 +/- 7 years; FEV(1), 56 +/- 14% predicted) performed constant-load endurance exercise on the treadmill and cycle ergometer at 85% of capacity after inhaling normal saline (NS) or arformoterol (ARF) (15 microg).
Results: Increases in endurance times and consistency of responses were greater with treadmill walking (Delta: 157 +/- 286 s; P = .024; 80% improved) than with cycle exercise (Delta: 110 +/- 219 s; P = .038; 65% improved) with ARF compared with NS. However, these changes were not significantly different. The slope of breathlessness-time (mean Delta = -29%; P = .007) and the magnitude of oxygen desaturation were significantly lower with ARF compared with NS during treadmill, but not cycle, exercise. Inspiratory capacity values were similar between modes of exercise when comparing the same study medication.
Conclusions: Improved endurance times support both constant-load treadmill and cycle exercise to assess the efficacy of bronchodilator therapy in patients with COPD. Unique differences in physiologic and perceptual responses with bronchodilation demonstrate advantages of treadmill walking as an exercise stimulus.
Trial registration: clinicaltrials.gov; Identifier: NCT00754546.