title: The Ergogenic Effect of Amphetamine.
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 VO2MAXand 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 VO2MAXand 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 VO2MAXbut 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.
authors: Department of Emergency Medicine, Indiana University School of Medicine, 720 Eskenazi Ave, Indianapolis, Indiana, USA, 46202.
authors: Dmitry V
authors: DV
authors: Zaretsky
authors: Department of Physical Therapy, Indiana University School of Health and Rehabilitation Sciences, 1140 W Michigan St, Indianapolis, Indiana, USA, 46202.
authors: Mary Beth
authors: MB
authors: Brown
authors: Department of Emergency Medicine, Indiana University School of Medicine, 720 Eskenazi Ave, Indianapolis, Indiana, USA, 46202.
authors: Maria V
authors: MV
authors: Zaretskaia
authors: Department of Emergency Medicine, Indiana University School of Medicine, 720 Eskenazi Ave, Indianapolis, Indiana, USA, 46202.
authors: Pamela J
authors: PJ
authors: Durant
authors: 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.
authors: Daniel E
authors: DE
authors: Rusyniak
keywords: Exertional heat stroke; Exhaustion; Running economy; VO2Max; amphetamine