Effects of the GABAergic agonist baclofen on endurance performance in recreational athletes: a pilot study

Aim. The neurocrine and neurovegetative systems have been shown to play a fundamental role in the overtraining syndrome of endurance athletes The aim of this study was to explore the effects of the oral administration of the GABAergic agonist baclofen on endurance performance in recreational athletes. Methods. A randomized crossover intervention trial involving 14 healthy male subjects (mean age 20.1 ±1.7 yrs, range 18 to 24 yrs; BMI 22.0±1.3) was conducted. Subjects were assigned to baclofen 10 mg or to placebo 1 hour before a maximal bicycle exercise test performed until exhaustion. Before and immediately after the exercise test, venous blood samples were collected for the determination of main biochemical parameters. Results. No significant differences between postexercise maximal values for VO 2max, workloads and run-time to exhaustion after treatment with baclofen or placebo were detected. Plasma haemoglobin, hematocrit, lactic acid, and ammonia concentrations significantly increased post-exercise both after treatment and after placebo. No statistical significance was found in metabolic parameters before and after exercise in baclofen or placebo treatment groups. Discussion. These results may be due to the low dosages used and further investigations with higher doses should be performed to explore possible effects of baclofen. Conclusion. Baclofen administration had no effect on endurance performance and on indicators of peripheral fatigue.