The prevalence of airways hyperresponsiveness in members of an exercise training facility

Athletes have a high prevalence (11-50%) of exercise-induced asthma, which may be caused by the hyperventilation accompanying repetitive bouts of strenuous exercise. We hypothesized that recreational exercisers would display a similar trend. Eucapnic voluntary hyperventilation (EVH) bronchoprovocation (breathing 21% O₂, 5% CO₂, and 74% N₂ at 60% of MVV for 5 minutes) was performed to determine the prevalence of airways hyperresponsiveness (AHR) in adults (n = 212, 146 males, mean ± standard deviation, age 32 ± 10 years) who exercised regularly (10 ± 10 years, 31 ± 28% of their lives): none had a previous diagnosis of asthma. AHR was defined by at least a 10%, 20%, or 25% decline in FEV₁, FEF_25-75, or PEFR, respectively, by spirometry at 1, 5, 10, and 15 minutes post-EVH. Forty-one of 212 (19%) tested positive for AHR: 20 of 41 (49%) were positive by FEV₁, 28 of 41 (68%) by FEF_25-75, and 27 of 41 (66%) by PEFR. Comparing responders with nonresponders: pre-EVH lung function was equivalent, except for FEV₁, which was reduced (p < 0.05) in responders (96 ± 13 vs. 102 ± 12% predicted). Mean maximal negative deflections for responders were: for FEV₁, -17 ± 7%; FEF_25-75, -31 ± 10%; PEFR, -38 ± 11%. Ranges of decline for responders were: FEV₁, -10 to -33%; FEF_25-75, -20 to -59%; PEFR, -25- to -70%. We conclude that in these regular exercisers, the prevalence of AHR is high and comparable with some athletic populations.