Received April 20, 2004
Revised June 2, 2004
Accepted after revision July 17, 2004

¹ Grampian University
² University of Aberdeen
³ Loughborough University

^* To whom correspondence should be addressed. E-mail: a.t.strachan{at}arh.grampian.scot.nhs.uk.

	Abstract

The purpose of the experiment was to examine whether selective serotonin (5-HT) re-uptake transporter blockade by paroxetine has any effect on perceived effort (RPE) during exercise or the time to reach volitional fatigue and on the prolactin and cortisol responses during prolonged exercise performed in a warm environment. Eight healthy males performed two cycle rides to exhaustion in a warm (32°C) environmental at 60% VO2max. Paroxetine (20 mg) or placebo was administered 5 hours before exercise trials in a randomised double blind fashion. Time to exhaustion was not significantly influenced by administration of paroxetine: median (range) time to exhaustion was 93.3 (76.2 - 175.0) minutes on the placebo trial and 92.5 (66.0 - 151.0) minutes on the paroxetine trial. Rectal temperature was higher at rest and throughout exercise on the paroxetine trial. The serum concentrations of prolactin and cortisol were determined throughout exercise as peripheral markers of central 5-HT activity. RPE increased over time but was not influenced by paroxetine administration. Prolactin and cortisol levels increased over time but paroxetine administration did not influence the hormone responses during exercise. In conclusion, acute administration of paroxetine failed to alter RPE, exercise capacity or the response of the determined peripheral hormone markers of central 5-HT activity during prolonged exercise in a warm environment.

Key Words: Exercise, Serotonin, Thermoregulation

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