Performance-enhancing or purely therapeutic? The Impact of acute, short-term, and chronic administration of asthma-related glucocorticoid therapy on athlete health, performance and recovery

Exercise-induced bronchoconstriction (EIB) is highly prevalent in elite athlete populations and requires pharmacological treatment such as inhaled corticosteroids (ICS) to manage the condition, or oral glucocorticoids (GC) in the event of serious emergency exacerbation. However, debate continues if access to these substances are not only therapeutic but also performance-enhancing. This thesis aimed to investigate the impact of acute, short-term, and chronic administration of asthma-related GC therapy on athlete health, performance, and recovery. The first experimental study (Chapter 4) examined in a population of elite swimmers the impact of diagnosing and initiating asthma therapy on airway health outcomes and real-world performance at major competitions. This study reinforced that elite athletes mandate the use of asthma therapy. However, initiating and maintaining treatment did not enhance major competition performance beyond the natural progression expected between events. Chapter 5 gave methodological development to prospective ICS experimental work (Chapter 6 and 7) by modelling beclomethasone dipropionate (BDP) deposition under different conditions, including slow and fast inhalation flow rates, and with or without a valved-holding chamber (VHC). The findings showed that the inhalation flow rate can significantly impact the delivery of BDP. Additionally, the use of a VHC would reduce the reliance on BDP device actuation coordination and improve the fine particle dose, thereby theoretically improving the mechanisms of action of ICS. Following this, experimental study 3 (Chapter 6) investigated the ergogenic potential of acute oral GC and ICS by comparing these two administration routes on initial 40-km cycling time-trial (TT) and subsequent recovery for a further 10-km TT performed on the same day. The results suggested that supratherapeutic dose of ICS did not improve performance. However oral GC may be "possibly beneficial" to initial TT performance. Neither administration route impacted recovery. Finally, experimental study 4 (Chapter 7) investigated the effect of short-term (14-day) administration of ICS on repeated bout 10-km cycling TT performance. The findings demonstrated that there was no improvement in performance or recovery from using high-dose ICS compared to a placebo condition. Collectively, the findings of this thesis support that elite athletes require asthma therapy, and the current WADA guidelines to allow ICS in-competition is appropriate due to the lack of an ergogenic effect when assessed using ecologically valid TT assessments or when used for therapeutic purposes within an elite athlete population. Oral GC should remain controlled with a therapeutic use exemption due to uncertainties of ergogenic impact, immunosuppressive effects, and well-established long-term health implications.