title: Increased bronchial parasympathetic tone in elite cross-country and biathlon skiers: a randomised crossover study.
abstract: BACKGROUND
  Increased parasympathetic activity in endurance-trained athletes has been reported by heart rate variability and pupillometry. Our primary objective was to assess parasympathetic activity and tone in the lower respiratory tract by investigating the effect of cholinergic antagonism by inhaled ipratropium bromide compared to the β2-receptor stimulating effect of inhaled salbutamol in elite cross-country and biathlon skiers. We also examined the medications' relationship to cholinergic sensitivity as measured by bronchial responsiveness to methacholine (PD20met).
  
  
  METHODS
  In a randomised crossover study, 20 cross-country and two biathlon skiers (14♂/8♀) aged 20-37 years from the Norwegian national teams measured reversibility to inhaled ipratropium bromide and inhaled salbutamol and PD20meton three separate days. A positive reversibility test was defined as an increase in forced expiratory volume in 1 s (FEV1) of ≥12%. Spirometry was performed before and 45 and 15 min after inhaled ipratropium bromide and inhaled salbutamol, respectively. Bronchodilating medication was withheld according to the European Respiratory Society (ERS) guidelines. Correlations were assessed by Pearson's correlation coefficient (r).
  
  
  RESULTS
  Five athletes had significant reversibility after inhaled ipratropium bromide, and none after inhaled salbutamol. Twelve athletes (54.5%) had PD20met<8 μmol (1.57 mg). PD20metcorrelated negatively with ▵FEV1after inhaled ipratropium bromide (r=-0.85, p<0.0001), but not after inhaled salbutamol (r=-0.308, p=0.16).
  
  
  CONCLUSIONS
  In elite skiers, cholinergic sensitivity (PD20met) had a highly significant inverse correlation to the cholinergic antagonism of inhaled ipratropium bromide, but not at all to the bronchodilating inhaled salbutamol. This markedly increased bronchial parasympathetic tone may represent an important cholinergic role in the development of skier's asthma.
authors.affiliation: Department of Sports Medicine, Norwegian School of Sport Sciences, Oslo, Norway.
authors.forename: J
authors.initials: J
authors.lastname: Stang
authors.affiliation: Immunology Lab, Faculty of Medicine, University of Porto, Porto, Portugal Immunoallergology Department, Centro Hospitalar São João EPE, Porto, Portugal.
authors.forename: M
authors.initials: M
authors.lastname: Couto
authors.affiliation: Department of Sports Medicine, Norwegian School of Sport Sciences, Oslo, Norway Department of Pediatrics, Oslo University Hospital, Oslo, Norway Faculty of Medicine, University of Oslo, Oslo, Norway.
authors.forename: K-H
authors.initials: KH
authors.lastname: Carlsen
authors.affiliation: Department of Sports Medicine, Norwegian School of Sport Sciences, Oslo, Norway.
authors.forename: T
authors.initials: T
authors.lastname: Stensrud
keywords: Asthma; Athlete; Respiratory; Skiing; Sports medicine