No effect of a noradrenergic reuptake inhibitor on performance in trained cyclists.
BACKGROUND
According to the central fatigue hypothesis, serotonin (5-HT) is related to fatigue, whereas the noradrenergic system is primarily concerned with arousal and motivation, and therefore hypothesized to enhance performance. The purpose of the present study was to examine the effects of a selective noradrenergic reuptake inhibitor (reboxetine 2 x 4 mg REB-NARI) on exercise performance.


METHODS
Seven healthy well-trained male cyclists (age: 23 +/- 1.7 yr, height: 182 +/- 5.8 cm, weight: 73.5 +/- 8.5 kg, VO2max: 73.5 +/- 6.4 mL x kg(-1) x min(-1), Watt(max): 376 +/- 11.7 W) participated to the study. Subjects completed two endurance tests (time trials) starting at 65% Wmax in a double-blind randomized cross-over design. Blood samples were collected for adrenocorticotropin, prolactin, cortisol, growth hormone (GH), beta-endorphins, and catecholamines and were taken at 30-min time intervals until the end of exercise. Performance was analyzed with a paired t-test, whereas data for hormonal and metabolic differences during the trials were analyzed using an ANOVA repeated measures design and an LSD-planned comparisons test. Significance level was set at P < 0.05.


RESULTS
Performance was not influenced by the NARI (REB: 97 min +/- 3 min, placebo (PLAC): 92 min +/- 1 min). All hormones increased during exercise except for GH in the REB trial, which was significantly lower than PLAC. The other hormones were significantly higher in the REB trial versus the PLAC trial at the end of exercise and during recovery.


CONCLUSIONS
In conclusion, the results demonstrate that the drug had a central effect. In particular, the higher resting GH concentrations indicated a marked and selective noradrenergic effect of REB. However, performance was not influenced by a selective NARI in well-trained endurance athletes.
Piacentini
Maria Francesca
MF
Department of Human Physiology and Sportsmedicine, Vrije Universiteit Brussel, Brussels, Belgium.
Meeusen
Romain
R
Buyse
Luk
L
De Schutter
Guy
G
Kempenaers
Farid
F
Van Nijvel
Joeri
J
De Meirleir
Kenny
K
D018759:Adrenergic Uptake Inhibitors / Q000494:pharmacology*; D000324:Adrenocorticotropic Hormone / Q000097:blood; D000328:Adult; D018592:Cross-Over Studies; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D013006:Growth Hormone / Q000097:blood; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D019344:Lactic Acid / Q000097:blood; D008297:Male; D009025:Morpholines / Q000494:pharmacology*; D009638:Norepinephrine / Q000097:blood; D005082:Physical Exertion / Q000187:drug effects* / Q000502:physiology; D011388:Prolactin / Q000097:blood; D000077593:Reboxetine; D013647:Task Performance and Analysis
D018759:Adrenergic Uptake Inhibitors; D009025:Morpholines; D019344:Lactic Acid; D000324:Adrenocorticotropic Hormone; D011388:Prolactin; D013006:Growth Hormone; D000077593:Reboxetine; D006854:Hydrocortisone; D009638:Norepinephrine