Airway hyperresponsiveness to methacholine, adenosine 5-monophosphate, mannitol, eucapnic voluntary hyperpnoea and field exercise challenge in elite cross-country skiers

Background Methacholine hyperresponsiveness is prevalent in elite athletes. Comparative studies have hitherto been limited to methacholine, eucapnic voluntary hyperpnoea and exercise. This study investigated airway responsiveness to these stimuli as well as to adenosine 5′-monophosphate (AMP) and mannitol, in 58 crosscountry ski athletes. Methods Exhaled nitric oxide concentration (F E NO), spirometry and bronchial challenge in random order with methacholine, AMP and mannitol were consecutively performed on three study days in the autumn. Specifi c IgE to eight aeroallergens and a self-completed questionnaire about respiratory symptoms, allergy and asthmatic medication were also performed on day 1. Eucapnic voluntary hyperventilation (EVH) and fi eld exercise tests were randomly performed in 33 of the skiers on two study days in the following winter. Results Of 25 (43%) skiers with airway hyperre-sponsiveness (AHR), 23, fi ve and three skiers were hyperresponsive to methacholine, AMP and mannitol, respectively. Methacholine hyperresponsiveness was more prevalent in subjects without asthma-like symptoms. The F E NO was not signifi cantly different in skiers with and without methacholine hyperresponsiveness. Four of 14 skiers with and four of 19 skiers without methacholine hyperresponsiveness were hyperrespon-sive to EVH or exercise challenge. AHR to any stimulus was present in 16 asymptomatic and nine symptomatic skiers. Asthma-like symptoms were not correlated with AHR to any stimulus. Conclusions Methacholine hyperresponsiveness is more common in asymptomatic skiers and is a poor predictor of hyperresponsiveness to mannitol and hyper-pnoea. The low prevalence of hyperresponsiveness to indirect stimuli may suggest differences in the patho-genesis of methacholine hyperresponsiveness in elite skiers and non-athletes. Highly trained athletes commonly report respiratory symptoms, asthmatic medication use, asthma, airway hyperresponsiveness (AHR) and exercise-induced bronchoconstriction (EIB). 1 – 7 AHR to indirect stimuli, such as exercise, eucapnic voluntary hyperventilation (EVH), hypo or hypertonic aerosols and adenosine 5′-monophosphate (AMP) is considered to be more specifi c for asthma than hyperresponsive-ness to a direct stimulus such as methacholine. EVH is more sensitive than sport-specifi c fi eld exercise or methacholine provocation and is the preferred test of the Medical Commission of the International Olympic Committee for the detection of EIB. 8 – 10 Provocation with dry powder mannitol has recently been proposed as an alternative to EVH. 11 Studies comparing airway responsiveness to different stimuli in elite athletes have hitherto been restricted to methacholine, EVH and fi eld-based or laboratory exercise. 9 12 13 In this study, we assessed AHR to methacholine, AMP and mannitol …