Predictors of Airway Hyperresponsiveness in Elite Athletes

INTRODUCTION: Elite athletes frequently suffer from 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: 57 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, 47 agreed to perform an additional methacholine provocation.

RESULTS: Based on a physician's diagnosis, 18 (32%) athletes were concluded to suffer from asthma. Asthmatic subjects trained more hours per week than the 39 non-asthmatics (median (min-max) 25 hours/week, (14-30) vs. 20 hours/week, (11-30), (p= 0.001)). AHR to both methacholine and mannitol (Dose Response Slope, DRS) increased with number of weekly training hours (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 non-asthmatics. 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). 15 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: Airway hyperresponsiveness 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.