Citable fact
«Caffeine» — evidence level A. Dosage: 3-6 mg/kg per serving; 200 mg also works. Doses above 9 mg/kg give no increase in effect but increase adverse effects. The form is caffeine or coffee. Source: PMID 33388079, permanent link to the source in the list below.
How it works
It blocks adenosine receptors, reducing the perception of effort and pain. It additionally increases calcium mobilization in muscle and the activity of the sympathetic system.
Dosage and intake
3-6 mg/kg per serving; 200 mg also works. Doses above 9 mg/kg give no increase in effect but increase adverse effects. The form is caffeine or coffee.
45-60 minutes before exercise. With regular use the effect partially weakens, so caffeine-free periods are reasonable.
Forms
Anhydrous caffeine, coffee, chewing gum and energy drinks have been studied. The effect is generally comparable, but dosing drinks is harder due to fluctuating content.
What is confirmed
- Meta-analysis of 21 reviews: improvement in endurance performance by an average of 2-4%
- Reduced subjective perception of effort during aerobic work
- A small but inconsistent gain in strength and power
- Improved reaction time and alertness under sleep deprivation
Adverse effects and limitations
- Insomnia when taken later than 6 hours before sleep, anxiety, tremor, rapid pulse
- It can mask fatigue and increase the risk of overreaching
- Habituation and withdrawal syndrome (headache, lethargy)
- In sensitive people - GI upset and increased blood pressure
Interactions
- Sympathomimetics, theophylline and some antibiotics enhance the effect and adverse effects
- Oral contraceptives and fluvoxamine slow caffeine metabolism
- Combination with ephedrine or large doses of other stimulants is dangerous for the heart
Who must not use it
- Under 18 years: Not recommended as an ergogenic supplement; in adolescents the risk of sleep disturbances is high.
- Pregnancy and lactation: Limited to 200 mg per day according to obstetric recommendations.
- arrhythmias
- uncontrolled hypertension
- anxiety disorders
- peptic ulcer disease
Sources
- International society of sports nutrition position stand: caffeine and exercise performance · Guest NS, VanDusseldorp TA, Nelson MT · Journal of the International Society of Sports Nutrition, 2021 · PMID 33388079
- Wake up and smell the coffee: caffeine supplementation and exercise performance-an umbrella review of 21 published meta-analyses · Grgic J, Grgic I, Pickering C · British journal of sports medicine, 2020 · PMID 30926628
- Pharmacology of stimulants prohibited by the World Anti-Doping Agency (WADA) · Docherty JR · British journal of pharmacology, 2008 · PMID 18500382
See also
Comparisons
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