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Caffeine intake improves intense intermittent exercise performance and reduces muscle interstitial potassium
Magni Mohr1, Jens Jung Nielsen, Jens Bangsbo
1Copenhagen Muscle Research Centre, Department of Exercise and Sport Sciences, University of Copenhagen, Denmark.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|August 13, 2011
Summary
Caffeine supplementation significantly improves intense intermittent exercise performance by enhancing fatigue resistance. It also reduces muscle interstitial potassium levels during strenuous exercise.
Area of Science:
- Exercise Physiology
- Sports Science
- Nutritional Biochemistry
Background:
- Caffeine is a widely used ergogenic aid known to affect performance.
- Its precise mechanisms, particularly concerning ion shifts during intense intermittent exercise, require further elucidation.
Purpose of the Study:
- To investigate the effects of oral caffeine intake on performance during intense intermittent exercise.
- To examine the impact of caffeine on muscle interstitial potassium (K+) and sodium (Na+) concentrations.
Main Methods:
- Two studies were conducted: Study 1 (S1) involved 12 subjects performing the Yo-Yo intermittent recovery level 2 (Yo-Yo IR2) test with caffeine (6 mg/kg body weight) or placebo. Study 2 (S2) involved 6 subjects performing one-legged knee-extension exercise bouts at varying intensities with or without caffeine, using microdialysis to measure interstitial ions.
Main Results:
- Yo-Yo IR2 performance was 16% higher with caffeine compared to placebo (P < 0.05).
- Caffeine ingestion led to higher plasma free fatty acids, peak blood glucose, and plasma ammonia.
- Muscle interstitial K+ was significantly lower during intense exercise with caffeine compared to control (P < 0.001), while interstitial Na+ showed no difference.
Conclusions:
- Oral caffeine intake enhances fatigue resistance and improves performance in intense intermittent exercise.
- Caffeine supplementation effectively reduces muscle interstitial K+ accumulation during such exercise protocols.
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