No Effect of a Selective Serotonergic/Noradrenergic Reuptake Inhibitor on Endurance Performance

The purpose of the present study was to examine the effects of a selective serotonin/noradrenaline (5-HT/NA) reuptake inhibitor (SNRI) on exercise performance. Seven well-trained male cyclists completed 2 time trials in a doubleblind randomized crossover design ingesting either placebo (PLAC) or 2 37.5 mg of Venlafaxine (VEN). Blood samples were collected for adrenocorticotropin hormone (ACTH), prolactin (PRL), cortisol, growth hormone (GH), beta-endorphins, and catecholamines and were taken at rest, at 30-min time intervals, at the end of exercise, and during recovery. Performance was not influenced by the SNRI (VEN: 92 min ± 3 min, PLAC: 92 min ± 1 min). Lactate concentrations, heart rate, and fatigue scores were not different between trials. All hormones increased during exercise in both trials. In the VEN trial, ACTH, beta endorphins, and NA concentrations were higher. The results from the present study demonstrate that a SNRI is not able to affect endurance performance in well-trained cyclists. However, it seems as though the hormonal response to the combination of the pharmacological manipulation and exercise is regulated more by the noradrenergic drive.