Effect of acute oral prednisolone and inhaled Beclomethasone Dipropionate on inflammatory cytokine response following 40-km cycling time-trial

INTRODUCTION & PURPOSE: The World-Anti Doping Agency (WADA) mandate that athletes with asthma-related conditions using glucocorticoid treatment obtain a therapeutic-use-exemption (TUE) during competition periods for orally delivered substances, but not for inhaled substances. Research on the impact of high-dose inhaled glucocorticoids on systemic inflammation following exercise is scarce. Therefore, this study aimed to investigate two glucocorticoid administration routes that differ in WADA legality on inflammatory cytokine response following a 40-km cycling time-trial (TT).

METHODS: In a randomised cross-over order, nine-trained male cyclists (V̇O2max; 59.1 ± 3.8 ml.kg.min-1) completed a 40-km time-trial four-hours after administration of acute oral prednisolone (0.5 mg.kg-1, PRED), inhaled beclomethasone dipropionate (1600 μg, BEC), microcrystalline cellulose capsules (O-PLA), water vapour inhaler (I-PLA) or control (CON). Plasma Interleukin-6 (IL-6) concentration was determined from samples collected at baseline, and immediately after completion of the 40-km TT. Plasma IL-6 concentrations were log-transformed, then statistically analysed using a repeated measures ANOVA with multiple comparisons.

RESULTS: Plasma IL-6 samples were successfully obtained in all conditions and time points from eight participants (n=8). Baseline IL-6 concentration was not significantly different between conditions. The 40-km TT induced a significant increase in IL-6 concentrations in all conditions (p < 0.05). However, PRED administration resulted in significantly lower IL-6 concentrations compared to all other conditions (Table 1, P<0.05).

CONCLUSION: Acute administration of 0.5 mg.kg-1 oral prednisolone blunted inflammatory cytokine response following a 40-km cycling TT. This effect was not evident in supratherapeutic doses of inhaled glucocorticoids. Oral glucocorticoids [such as prednisolone] should remain controlled by WADA due to the ability to induce systemic anti-inflammatory properties. This study adds evidence that WADA guidelines to allow inhaled glucocorticoids [such as beclomethasone dipropionate] are appropriate.