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Temperature (Austin). 2014;1(3):242-247. Epub 2014 Nov 24.

The Ergogenic Effect of Amphetamine.

Author information

1
Department of Emergency Medicine, Indiana University School of Medicine, 720 Eskenazi Ave, Indianapolis, Indiana, USA, 46202.
2
Department of Physical Therapy, Indiana University School of Health and Rehabilitation Sciences, 1140 W Michigan St, Indianapolis, Indiana, USA, 46202.
3
Department of Emergency Medicine, Indiana University School of Medicine, 720 Eskenazi Ave, Indianapolis, Indiana, USA, 46202; Department of Pharmacology and Toxicology, Indiana University School of Medicine, 635 Barhill Drive, Indianapolis, Indiana, USA, 46202.

Abstract

Amphetamine (Amp) increases exercise duration. It is thought to do so by masking fatigue, but there have been very few studies looking at the effect of amphetamine on VO2MAX and running economy. Furthermore, it is unknown if amphetamine's effect on exercise duration occurs in a warm environment. We conducted separate experiments in male Sprague-Dawley rats testing the effect of amphetamine on maximal oxygen consumption (VO2MAX) (n=12), running economy (n=12), and exercise duration (n=24) in a warm environment. For VO2MAX and running economy, rats were randomized to either amphetamine at 1 mg/kg (Amp-1) or 2 mg/kg (Amp-2). Animals served as their own controls in a crossover design with the administration order counter-balanced. To study the effect of amphetamine on exercise duration, we conducted run-to-exhaustion treadmill testing on rats in a 32°C environment following administration of Amp-1, Amp-2, or Saline. Compared to control, Amp-2 increased VO2MAX (by 861 ± 184 ml/kg/hr, p=0.005) and the time to VO2MAX (by 2.5 ± 0.8 min, p=0.03). Amp-1 had no effect on VO2MAX but increased the time to VO2MAX (by 1.7 ± 0.5 min, p=0.03). Neither dose improved running economy. In the warm, only rats in the Amp-1 group (+9.4 min, p=0.02) had an increased time to exhaustion. Compared to control (41.6 ± 0.3°C), both amphetamine doses had higher temperatures at exhaustion: Amp-1 (42.0 ± 0.2°C) and Amp-2 (42.1 ± 0.2°C). Our results suggest that ergogenic effect of amphetamine occurs by masking fatigue but this effect may be offset in the warm with higher doses.

KEYWORDS:

Exertional heat stroke; Exhaustion; Running economy; VO2Max; amphetamine

Conflict of interest statement

There are no conflicts of interest, financial or otherwise, declared by the authors.

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