The effects of acute dopamine reuptake inhibition on performance

Introduction: Acute bupropion (BUP; dopamine/noradrenaline reuptake inhibitor) administration significantly improved time trial performance and increased core temperature in the heat (30°C). Purpose: The present study was performed to examine the effect of a dopaminergic reuptake inhibitor on exercise capacity and thermoregulation during prolonged exercise in temperate and warm conditons. Methods: Eight healthy well-trained male cyclists participated in this study. Subjects ingested either a placebo (PLAC; lactose; 20mg) or Ritalin (RIT; methylphenidate (MPH); 20mg) one hour before the start of exercise in temperate (18°C) or warm (30°C) conditions and cycled for 60 min at 55% Wmax, immediately followed by a time trial (TT; pla18 and rit18; pla30 and rit30) to measure exercise performance. Results: Ritalin did not influence TT performance at 18oC (P=0.397). TT was completed 16% faster in rit30 (38.1±6.4min) than in pla30 (45.4±7.3min; p=0.049). Power output was higher in rit30, compared to pla30 (p<0.05). In the heat Tcore was significantly higher at rest (p=0.009), at the start of exercise and throughout rit30 (p<0.05). Throughout rit30 heart rates were significantly higher (p<0.05). Prolactin concentrations decreased after one hour cycling in 18°C (p=0,036) and at rest in 30°C (p=0,007) after RIT administration. Conclusions: These results show that RIT has a clear ergogenic effect that was not apparent in 18°C. The combination of a dopamine reuptake inhibitor and exercise in the heat clearly improved performance and appeared to increase metabolic heat production, suggesting an important role for dopamine in the fatigue process.