Airway Response to Methacholine following Eucapnic Voluntary Hyperpnea in Athletes

AIM: To evaluate the changes in airway responsiveness to methacholine inhalation test (MIT) when performed after an eucapnic voluntary hyperpnea challenge (EVH) in athletes. METHODS: Two MIT preceded (visit 1) or not (visit 2) by an EVH, were performed in 28 athletes and 24 non-athletes. Twelve athletes and 13 non-athletes had airway hyperresponsiveness (AHR) to methacholine, and 11 athletes and 11 non-athletes had AHR to EVH (EVH+). RESULTS: The MIT PC(20) post-EVH was significantly lower compared to baseline MIT PC(20) by 1.3±0.7 doubling-concentrations in EVH+ athletes only (p<0.0001). No significant change was observed in EVH- athletes and EVH+/EVH- non-athletes. A significant correlation between the change in MIT PC(20) post-EVH and EVH+/EVH- status and athlete/nonathlete status was found (Adjusted R(2)=0.26 and p<0.001). Three (11%) athletes and one (4%) non-athlete had a change in the diagnosis of AHR when MIT was performed consecutively to EVH. CONCLUSION: The responsiveness to methacholine was increased by a previous indirect challenge in EVH+ athletes only. The mechanisms for such increase remain to be determined. MIT and EVH should ideally be performed on separate occasions as there is a small but possible risk to obtain a false-positive response to methacholine when performed immediately after the EVH. TRIAL REGISTRATION: ClinicalTrials.gov NCT00686491