Caffeine: what does it do for your training?

This is general information, not medical advice. Always discuss your blood values with your doctor.

1. 1

   It works for strength and endurance

   An umbrella review of 11 reviews with 21 meta-analyses (Grgic et al., BJSM 2020), all of moderate or high quality, found that caffeine improves performance in aerobic endurance, muscle strength, muscular endurance, power, jumping and speed. Not every analysis showed a clear direction once the prediction interval is taken into account, and most studies were in young men. The effect is real, but it differs per person and per type of effort.

2. 2

   Dose and timing: 3 to 6 mg per kilo, an hour before

   According to the International Society of Sports Nutrition position stand (2021), caffeine consistently improves performance at 3 to 6 mg per kilo of body weight, and the lowest effective dose may be around 2 mg per kilo. Very high doses (9 mg per kilo or more) often cause side effects without extra benefit. It is most often taken about 60 minutes before training, although the ideal timing depends on the source. Your response, including on sleep and anxiety, differs per person, partly because of genetic differences in how you metabolise caffeine.

3. 3

   Safe limits according to EFSA

   The European Food Safety Authority (EFSA, 2015) sees no safety concern for single doses up to 200 mg (about 3 mg per kilo for a 70 kg adult), even shortly before intense exercise, or for daily intakes up to 400 mg in adults who are not pregnant. For pregnant and breastfeeding women the limit is 200 mg a day. Note: the top of the sports range (6 mg per kilo) is above that 200 mg per dose for most people. So start low and only build up if you tolerate it well.

4. 4

   Sleep: the price of caffeine late in the day

   A meta-analysis of 24 studies (Gardiner et al., Sleep Medicine Reviews 2023) found that caffeine shortened total sleep time by 45 minutes on average and sleep efficiency by 7%. Falling asleep took 9 minutes longer, time awake after sleep onset 12 minutes longer, and deep sleep fell by about 11 minutes. To avoid losing sleep time, coffee (107 mg per 250 mL) should be consumed at least 8.8 hours before bedtime and a standard pre-workout (217.5 mg) at least 13.2 hours before. If you train in the evening, that is a real trade-off.

Updated in October 2026