Prevalence, diagnosis and treatment of exercise induced asthma in elite athletes

Abstract

An acute asthmatic episode can occur following exercise and is termed exercise induced asthma (EIA). The purpose of this thesis was to investigate the prevalence, diagnosis, and treatment of EIA in elite British athletes. The addition of objective pulmonary function assessment to the criteria an athlete must submit to use inhaled 02-agonists at Olympic Games may result in a change in the prevalence of asthma within elite athletes. The purpose of study 1 was to compare the prevalence of asthma at the 2000 and 2004 Olympic Games in the Great British Olympic team (Team GB). The asthma prevalence of Team GB reported in 2000 (21.2%) was similar to the asthma prevalence reported in 2004 (20.7%). 13 out of 62 (21.0%) athletes, from 2004 Team GB with a previous diagnosis of asthma failed to present evidence of EIA. The overall asthma prevalence of Team GB remained unchanged between 2000 and 2004. Mid-expiratory airflow measurements may improve the diagnosis of EIA in elite athletes. Study 2 investigated the response of Forced Expiratory Flow at 50% vital capacity (FEFso) following eucapnic voluntary hyperpnoea (EVH) and exercise challenge, in elite athletes, as an adjunct to Forced Expiratory Volume in one second (FEVI). 66 male and 50 female athletes were tested for EIA. Sixty athletes demonstrated a fall in FEVI >10% leading to the diagnosis of EIA. Using the FEF50 criteria (1FEF50 >-26%) led to 21 (35%) asthmatic athletes receiving false negative diagnosis. The addition of FEF50 failed to enhance the diagnosis of EIA in elite athletes. It is unclear, between exercise and EVH challenges as to which one provides the greatest sensitivity and most suitable method of EIA diagnosis in elite athletes. Study 3 investigated the response of elite winter athletes to EVH and two exercise challenges (laboratory-based [LB] and sport-specific [SS]). 14 athletes from the British Short-track Speed Skating and Biathlon teams volunteered for the study. Ten athletes presented with a positive response to EVH (71%); of these, only 3 (21%) had a positive response to the SS challenge. No athletes had a positive test to the LB challenge. Our results suggest that the EVH challenge is more sensitive, compared with either LB or SS exercise challenge, to diagnose EIA in elite winter athletes. A limited number of studies exist examining the optimal pharmacotherapy for elite athletes with EIA. The purpose of study 4 was to examine the effects of fluticasone propionate and salmeterol in the control of EIA in athletes. Eight athletes were prescribed 200mcg fluticasone propionate (FLU), 50mcg Salmeterol (SAL), 250mcg fluticasone propionate and salmeterol in combination (FXS) or placebo (PLA), in a randomised double blind design. No significant (p=0.07) differences were observed in the FEV1 change (zFEV1) following EVH challenge between the 4 treatments. Baseline eNO for both FXS (20.3 +/- 8.2ppb) and FLU (19.7 +/- 9.2 ppb) were significantly (p=0.02) lower than SAL (39.3 +/- 26.7ppb) or PLA (46.3 +/- 26.8ppb). Four athletes were prescribed FLU, 2 athletes were prescribed FXS and 2 athletes were prescribed SAL. The results of this study demonstrate the heterogeneity of response in elite athletes with EIA to the three medication regimes employed. Therefore, suggesting differences in the pathogenesis of EIA in this population. This thesis is the first to investigate EIA within elite British athletes. The prevalence of asthma within elite athletes is greater than that of the British general population. Optimal EIA diagnostic methods should include EVH challenges using FEV1 as the criterion measurement. Treatment for athletes with EIA should be taken on an individual basis due to the heterogeneity of response to medications that attenuate EIA in elite athletes.