Diagnosis and management of exercise induced bronchoconstriction in athletes

It is now well established that there is a high prevalence of exercise-induced bronchoconstriction (EIB) amongst athletes. There is still debate however regarding the optimal method of diagnosis in this group and current treatment guidelines are mainly based on recommendations for the general population with asthma. The aim of this thesis was to address these gaps in the literature by investigating methods of diagnosing EIB, the impact of standard asthma treatment upon airway inflammation, EIB severity, health and performance in elite athletes, and the effect of reducing environmental exposure upon EIB severity.

Study 1 compared two objective methods of diagnosing EIB; eucapnic voluntary hyperpnoea (EVH) and an exercise challenge (EX) on a cycle ergometer in a dry (26%RH) environment. Twenty-seven recreational athletes completed both an EVH and EX challenge in a randomised order. Challenges were deemed positive if there was a fall in FEV1 of ≥ 10% from pre to post challenge. Six participants were positive to EVH (% fall in FEV1 16 ± 5%, range -11 to -25%), of these, only two were positive to Ex (both with an 11% fall in FEV1). These findings demonstrated that EVH provides greater sensitivity than a standardised EX challenge in a dry environment in the diagnosis of EIB.

Study 2 reports results of the largest EIB screening in elite footballers to date and evaluates the prevalence of EIB and the impact of standard asthma therapy on airway health and exercise performance. Ninety-seven male professional football players completed an EVH challenge. Players demonstrating a positive result (EVH+) were prescribed standard asthma therapy and underwent repeat assessment after 9 weeks of treatment. Eight players (3 EVH+, 5 EVH-) completed a V̇O2 peak test at initial and follow-up assessments. Of the 97 players, 27 (28%) demonstrated EVH+. Seven of the 27 (24%) EVH+ players attended follow-up and demonstrated improved post-challenge spirometry (FEV1 post-test; pre = -22.9 ± 15.4%, post = -9.0 ± 1.6%, p = 0.018). At follow-up V̇O2 peak improved by 3.4 ± 2.9 ml/kg/min in EVH+ players compared to 0.1 ± 2.3 ml.kg-1.min-1 in EVH- players. It was concluded that elite footballers have a high EIB prevalence and treatment with inhaler therapy reduces EIB severity and may also lead to improved exercise performance.

In study 3 a three-part body of work with elite British swimmers was undertaken: (I) To investigate the effects of screening for EIB and treating appropriately on health and availability for training. (II) To monitor lung function, airway inflammation and respiratory symptoms in relation to a change in training environment from an indoor to an outdoor pool. (III) To report the findings of a systematic evaluation of total airway health in elite swimmers with EIB. A 75% prevalence of EIB was found in swimmers entering the GB funded programme. Treating this group with standard asthma therapy led to no differences in the percentage of time swimmers spent carrying out modified training in the 6 months post screening compared to the 6 months pre-screening (p = 0.17). No differences were found in FEV1 (p = 0.41), FeNO (p = 0.12) or PNIF (p = 0.67) in response to a change in training environment to an outdoor pool. Despite being prescribed treatment for EIB on assessment 3 swimmers still demonstrated airflow obstruction at rest with bronchodilator reversibility of FEV1 by 12.9 ± 7.7% above baseline. FeNO was reduced compared to initial consult (pre: 27.7 ± 15.1, post: 16.3 ± 6.5 ppb (p < 0.01). It was concluded that respiratory health in elite swimmers can be optimised through systematic assessment, however larger well controlled studies are still required to determine the impact of this approach upon performance and wellness.

Study 4 investigated if a heat and moisture exchange mask (HME) face mask could be effective in protecting against EIB in response to a cycle challenge in a cold, dry environment (9°C, 24% RH) in asthmatic individuals. Seventeen participants completed three EXs on a cycle ergometer wearing either an HME mask (MASK), a sham mask (SHAM) or no mask (CON) in a randomised order. There was a significant difference in the % fall in FEV1 following EX (MASK: -6.00, SHAM: -10.00, CON: -13.00%, p