Last updated: 3 October 2026
Reviewed by Jordan Morley, FA Level 2 Football Coach
Caffeine is the most evidence-backed ergogenic (performance-enhancing) aid. At 3-6mg per kg bodyweight, taken 30-60 minutes before exercise, it improves endurance, strength, power output, reaction time and focus by blocking adenosine receptors and reducing perceived exertion. Tolerance develops with regular use, so some athletes cycle their intake. Caffeine’s half-life (~5-6 hours) means afternoon and evening intake impairs sleep — which harms recovery more than the caffeine helps performance.
- Most effective legal ergogenic aid
- 3-6mg/kg, 30-60 min pre-exercise
- Improves endurance, strength, power, focus
- Avoid late-day use (impairs sleep)
In practice
Caffeine is one of the most research-backed legal performance aids in sport — a dose of roughly 3-6mg per kg of bodyweight, taken 30-60 minutes before exercise, has been shown to improve endurance performance, reduce perceived effort and even modestly boost power output, though regular heavy daily caffeine users typically see a smaller performance benefit than infrequent users.
FAQ
How much caffeine should I take before a workout or race?
Most research supports 3-6mg per kg of bodyweight (roughly 200-400mg for most adults), taken 30-60 minutes beforehand — higher doses show diminishing returns and more side effects.
Does caffeine tolerance reduce its performance benefit?
Yes — people who consume caffeine daily tend to experience a smaller ergogenic effect than those who use it occasionally, since the body adapts to regular intake.