Walking versus cycling: sensitivity to bronchodilation in chronic obstructive pulmonary disease.
BACKGROUND
There is no consensus regarding which exercise test to use to evaluate the functional impact of bronchodilators in patients with chronic obstructive pulmonary disease.


OBJECTIVE
Bronchodilator-induced changes in endurance time were evaluated during cycling and walking in 17 patients with chronic obstructive pulmonary disease who completed two cycle endurance tests and two endurance shuttle walks at 80% of peak capacity. Each endurance test was preceded by the nebulization of a placebo or 500 microg of ipratropium bromide using a randomized, double-blind, crossover design. Quadriceps twitch force was measured with magnetic stimulation of the femoral nerve before and after each endurance test.


RESULTS
Cycling endurance time did not improve significantly after bronchodilation despite a significant increase in FEV1 (delta endurance time ipratropium bromide - placebo: 51 +/- 255 s, p = 0.42). A similar change in FEV1 was associated with a significant improvement in walking endurance time (delta endurance time ipratropium bromide - placebo: 164 +/- 177 s, p < 0.01). A 22 +/- 17% fall in quadriceps twitch force was observed after cycling, whereas no significant change was seen after walking.


CONCLUSIONS
The endurance shuttle walk is a sensitive test to detect changes in exercise tolerance after bronchodilation. Differences in the occurrence of quadriceps muscle fatigue may explain, in part, the different responsiveness to change between cycling and walking.
Pepin
Véronique
V
Centre de Recherche, Hôpital Laval, Institut Universitaire de Cardiologie et de Pneumologie de l'Université Laval, Ste-Foy, PQ, Canada.
Saey
Didier
D
Whittom
Francçois
F
LeBlanc
Pierre
P
Maltais
Francçois
F
D000368:Aged; D000369:Aged, 80 and over; D001642:Bicycling / Q000502:physiology*; D001993:Bronchodilator Agents / Q000627:therapeutic use*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D009241:Ipratropium / Q000627:therapeutic use*; D008875:Middle Aged; D018763:Muscle Fatigue / Q000502:physiology; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy / Q000503:physiopathology*; D016138:Walking / Q000502:physiology*
D001993:Bronchodilator Agents; D009241:Ipratropium