Vagal activity and airway response to ipratropium bromide before and afterexercise in ambient and cold conditions in healthy cross-country runners

Objective: To determine whether the variability in the effect of ipratropiu m bromide on the bronchial response to exercise among endurance athletes de pends on their vagal activity. The hypothesis was that this would be the ca se. Design: Participants served as their own controls in a double-blind, repeat ed-measures investigation. Setting: Climatic chamber in an exercise laboratory. Participants: Six well-trained healthy adult cross-country runners (three w omen and three men). Interventions: Four exercise provocation tests at ambi ent temperature of 22 or -5 degrees C after inhalation of ipratropium bromi de or placebo. Main Outcome Measures: Vagal activity was assessed in each visit by a 4-sec ond cycling teal; airway response to exercise was measured by periodic pulm onary function testing. Results: With ipratropium bromide, forced expiratory volume in I second (FE V,) increased by 5.3 +/- 1.4% at 22 degrees C and by 7.5 +/- 1.5% at -5 deg rees C. The beneficial response of the large airways to ipratropium bromide versus placebo was positively related to vagal activity for FEV, at -5 deg rees C, for peak expiratory flow (PEF) at -5 degrees C, and for PEF at 22 d egrees C. Conclusion: The findings suggest that the beneficial large-airways response to ipratropium bromide may be related to vagal activity. Clinical Relevance: Information about vagal activity may help to determine whether an athlete is a suitable candidate for treatment with ipratropium b romide. This may offer more therapeutic possibilities, especially for those individuals who have a high vagal activity, such as endurance athletes.