Exhaled breath temperature in elite swimmers: The effects of a training session in adolescents with or without asthma

BackgroundCooling of the airways and inflammation have been pointed as possible mechanisms for exercise-induced asthma (EIA). We aimed to investigate the effect of training and asthma on exhaled breath temperature (EBT) of elite swimmers. MethodsElite swimmers annually screened (skin prick tests, spirometry before and after salbutamol inhalation, induced sputum cell counts, and methacholine bronchial challenge) at our department (n=27) were invited to this prospective study. Swimmers who agreed to participate in the present study (n=22, 10 with asthma) had axillary temperature and EBT measured (X-halo((R))) before and after a swimming training session (aerobic/non-aerobic). Linear regression models were used to assess the effect of asthma and other possible explanatory variables (demographics, PD20, baseline EBT, training intensity, axillary temperature, and the number of hours trained in that week) on EBT change. ResultsEBT significantly increased after training independently of lung function, airway responsiveness, and inflammation in all swimmers (meanSD: 0.32 +/- 0.57; p=0.016). No differences were observed between asthmatic swimmers and others. A significant correlation was observed between baseline and post-exercise EBTs (r=0.827, p<0.001). Asthma was not a predictor of EBT after adjusting for confounders; baseline EBT was the variable most strongly associated with EBT, explaining by itself alone 46% of the outcome (r(2)=0.464). ConclusionAlthough these are preliminary data, a relationship between airway's inflammation and respiratory heat loss during exercise could not be confirmed, suggesting that the increase in exhaled breath temperature is a physiologic rather than a pathological response to exercise.