Caffeine

Evidence ratingModerate

A pre-workout staple. Alongside alertness and focus, it gives a small boost to strength, power and endurance. Tolerance builds with habitual use, so timing matters.

An ingredient with growing research

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Effects reported in research

Small gains in maximal strength and power

Improved endurance performance

Greater alertness and lower perceived exertion

Dosage & timing

3–6 mg/kg body weight, 30–60 min before training.
Avoid late in the day to protect sleep.

Cautions

•Excess causes palpitations, insomnia and anxiety.
•Consult a doctor if pregnant or with heart conditions.
•Watch total intake when combining with energy drinks.

Supporting research

Meta-analysis

Caffeine ingestion improves muscular strength and power (meta-analysis)

Journal of the International Society of Sports Nutrition, 2018

Pooling RCTs, caffeine produced small but significant improvements in maximal strength and power. Effect sizes were modest and influenced by individual variation and tolerance.

View study details

Last checked: 2026-06-18