How much caffeine do you actually need before training?
More Caffeine Isn't Better: ~3 mg/kg Worked Best in 48 Studies
· By Anthony Falcone
Verdict: Keep it. Caffeine works, and a low dose does the job. About 3 mg per kg of body weight in a capsule matched or beat higher doses for endurance time trials, with fewer side effects.
What the researchers compared
The review pooled 48 studies where healthy adults did an endurance time trial — cycling, running, rowing — after caffeine or a placebo.
It compared doses (low: up to 3 mg per kg of body weight; moderate: 4–6 mg/kg) and forms: capsules or tablets, caffeinated gum and caffeine mouth rinse.
What they found
Low-dose capsules (about 3 mg/kg) cut completion time by 2.2% compared with placebo — slightly more than moderate-dose capsules (1.8%) or moderate-dose gum (1.6%). Low and moderate doses were not significantly different from each other.
Mouth rinsing had little effect, likely because almost no caffeine is absorbed in a 5–10 second rinse.
Because lower doses come with fewer side effects such as palpitations, poor sleep and stomach upset, the authors call ~3 mg/kg capsules the most practical choice.
A 2% improvement sounds small, but in a race decided by seconds it matters. For the rest of us, it means you don't need a huge dose to feel the benefit.
What this means for you
- Start low: around 3 mg per kg of body weight (≈210 mg at 70 kg) before a hard endurance session.
- Capsules gave the best results here. Whatever the form, a measured dose beats guessing.
- Late-day caffeine costs you sleep. If you train in the evening, consider a lower dose or none.
How much to trust it
- Almost 9 in 10 participants were men, so results may differ for women.
- All studies were endurance time trials; strength and team-sport performance weren't covered.
- Some comparisons were indirect, and the analysis couldn't separate the placebo effect.
The study
Xue R, Huang J, Chen B, Ding L, et al. Effects of Caffeine Dose and Administration Method on Time-Trial Performance: A Systematic Review and Network Meta-Analysis. Nutrients, 2025. doi.org/10.3390/nu17233792
Our Pre-Workout Protocol shows you how to build your own pre-workout, including caffeine dosing and cycling so it keeps working. See the protocol