Predictors of Airway Hyperresponsiveness in Elite Athletes

Introduction: 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-alpha), 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(-1) (14-30) versus 20 h.wk(-1) (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-alpha, 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-alpha (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). Conclusion: AHR in elite athletes is related to the amount of weekly training and the level of serum TNF-alpha. No association was found between the level of AHR to mannitol and methacholine in the asthmatic athletes.