title: Predictors of airway hyperresponsiveness in elite athletes.
abstract: BACKGROUND
  Elite athletes frequently experience asthma and airway hyperresponsiveness (AHR). We aimed to investigate predictors of airway pathophysiology in a group of unselected elite summer-sport athletes, training for the summer 2008 Olympic Games, including markers of airway inflammation, systemic inflammation, and training intensity.
  
  
  METHODS
  Fifty-seven Danish elite summer-sport athletes with and without asthma symptoms all gave a blood sample for measurements of high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor alpha (TNF-α), completed a respiratory questionnaire, and underwent spirometry. Bronchial challenges with mannitol were performed in all 57 athletes, and 47 agreed to perform an additional methacholine provocation.
  
  
  RESULTS
  Based on a physician's diagnosis, 18 (32%) athletes were concluded to be asthmatic. Asthmatic subjects trained more hours per week than the 39 nonasthmatics (median (min-max): 25 h·wk (14-30) versus 20 h·wk (11-30), P = 0.001). AHR to both methacholine and mannitol (dose response slope) increased with the number of weekly training h (r = 0.43, P = 0.003, and r = 0.28, P = 0.034, respectively). Serum levels of IL-6, IL-8, TNF-α, and hs-CRP were similar between asthmatics and nonasthmatics. However, there was a positive association between the degree of AHR to methacholine and serum levels of TNF-α (r = 0.36, P = 0.04). Fifteen out of 18 asthmatic athletes were challenged with both agents. In these subjects, no association was found between the levels of AHR to mannitol and methacholine (r = 0.032, P = 0.91).
  
  
  CONCLUSIONS
  AHR in elite athletes is related to the amount of weekly training and the level of serum TNF-α. No association was found between the level of AHR to mannitol and methacholine in the asthmatic athletes.
authors.affiliation: 1Department of Respiratory Medicine, Respiratory Research Unit, Bispebjerg Hospital, University of Copenhagen, DENMARK, and 2Department of Medicine, Roskilde Hospital, DENMARK.
authors.forename: Louise L
authors.initials: LL
authors.lastname: Toennesen
authors.forename: Celeste
authors.initials: C
authors.lastname: Porsbjerg
authors.forename: Lars
authors.initials: L
authors.lastname: Pedersen
authors.forename: Vibeke
authors.initials: V
authors.lastname: Backer
mesh_terms: D000328:Adult; D001249:Asthma / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology*; D015415:Biomarkers / Q000097:blood; D016535:Bronchial Hyperreactivity / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology*; D001985:Bronchial Provocation Tests; D002097:C-Reactive Protein / Q000378:metabolism; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000097:blood; D016209:Interleukin-8 / Q000097:blood; D008297:Male; D008353:Mannitol; D016210:Methacholine Chloride; D010806:Physical Education and Training; D013147:Spirometry; D013177:Sports / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000097:blood; D055815:Young Adult
chemical_list: D015415:Biomarkers; D015850:Interleukin-6; D016209:Interleukin-8; D014409:Tumor Necrosis Factor-alpha; D016210:Methacholine Chloride; D008353:Mannitol; D002097:C-Reactive Protein