The Ergogenic Effect of Amphetamine

Area of Science:

• Exercise Physiology
• Pharmacology
• Animal Models

Background:

• Amphetamine (Amp) is known to increase exercise duration, potentially by masking fatigue.
• Limited research exists on amphetamine's effects on maximal oxygen consumption (VO2MAX) and running economy.
• The impact of amphetamine on exercise performance in warm environments remains largely uninvestigated.

Purpose of the Study:

• To investigate the effects of amphetamine on VO2MAX, running economy, and exercise duration in rats.
• To determine if amphetamine's ergogenic effects persist in a warm environment (32°C).
• To explore the relationship between amphetamine dosage and physiological responses during exercise.

Main Methods:

• Male Sprague-Dawley rats were used in separate experiments for VO2MAX, running economy, and exercise duration.
• Rats received amphetamine at 1 mg/kg (Amp-1) or 2 mg/kg (Amp-2) or saline in a crossover or run-to-exhaustion design.
• Measurements included VO2MAX, running economy, time to exhaustion, and body temperature at exhaustion in a 32°C environment.

Main Results:

• Amphetamine at 2 mg/kg significantly increased VO2MAX and time to reach VO2MAX compared to control.
• Amphetamine at 1 mg/kg increased time to reach VO2MAX but did not affect VO2MAX or running economy.
• In warm conditions, only Amp-1 significantly increased exercise duration, while both doses elevated exhaustion temperatures.

Conclusions:

• Amphetamine's ergogenic effect on exercise appears to be mediated by fatigue masking.
• Higher doses of amphetamine may have diminished ergogenic effects in warm environments due to increased body temperature.
• These findings highlight the complex interaction between amphetamine, exercise intensity, and environmental temperature.