Purpose: It was investigated whether oral dexamethasone (DEX) administration improves exercise performance by reducing the initial rate of muscle fatigue development during dynamic exercise.
Methods: Using a double-blinded placebo controlled randomized crossover design, subjects ingested either 2 × 2 mg of DEX or placebo for five consecutive days. Muscle function was investigated using one-legged kicking exercise and whole body performance was evaluated using a 20-m shuttle run and a 30-m sprint test.
Results: One-legged dynamic knee-extensor exercise time to exhaustion was 29 ± 35% (mean ± SD) longer (P < 0.05) in DEX compared to Placebo. Likewise, total running distance in the shuttle run test was 19 ± 23% longer (P < 0.05), whereas 30-m sprint performance was unaltered. During the initial 75 s of dynamic leg extensions, peak force and rate of force development determined from an electrically evoked twitch declined in a similar way in DEX and placebo. Similarly, the EMG root mean square was similar with DEX and placebo treatment.
Conclusion: Short-term dexamethasone administration increases high-intensity one-legged kicking time to exhaustion and 20-m shuttle run performance, although sprint ability and the initial loss of muscular force generating capacity are similar after DEX and placebo.