If you were to keep only one ingredient from everything pre-workouts promise, it would be caffeine. Not because it's the most spectacular, but because it's the only one with an immediate effect, and by far the best documented: 21 meta-analyses, and an expert position that fits within a dosage range.
This guide answers the four recurring questions: how much, when, does it still work if I already drink coffee every day, and what does it do to my sleep if I train in the evening. And it starts with what the dosage range has as a flip side: beyond that, caffeine is dangerous. It extends our pre-workout guide, ingredient by ingredient.
It works. An umbrella review of 21 meta-analyses in the BJSM : caffeine improves aerobic endurance, strength, muscular endurance, power, jumping, and speed, with moderate quality evidence, and more so in aerobic than anaerobic conditions. How much. 3 to 6 mg per kilo according to the ISSN, or 210 to 420 mg for 70 kg, possibly from 2; never 9. When. 60 minutes before, in capsule or beverage form.
Tolerance doesn't block anything. Forty cyclists, usually consuming 58 to 351 mg per day: all gained approximately 3% on a time trial with 6 mg per kilo. Evening use. 400 mg taken six hours before bed still significantly reduces sleep. Excess is dangerous : anxiety, heart palpitations, tachycardia, and at high doses or through accumulation, documented cardiac arrhythmias and death.
Caffeine has an effective range, 3 to 6 mg per kilo, and a downside. Beyond that, it causes nervousness, anxiety, tremors, heart palpitations, accelerated heart rate, nausea, and insomnia ; the ISSN position notes that at 9 mg per kilo, the incidence of adverse effects is high without any performance gain. At higher doses, clinical toxicology describes cardiac arrhythmias, seizures, and death, documented from several grams onwards, but also, in young adults, serious accidents at doses not previously thought to be dangerous, most often through accumulation of energy drinks, supplements, and coffee consumed on the same day.
In a survey of 872 pre-workout users, 54% report adverse effects, including cardiac rhythm abnormalities, and 14% double the dose. The caffeine from one serving adds to that from morning coffee, tea, and afternoon energy drink: it's the total that matters. Palpitations, chest pain, discomfort, sudden anxiety : stop immediately and consult a doctor. Hypertension, known heart rhythm disorder, pregnancy, anxiety disorder, treatment interacting with caffeine: no caffeine at sports doses without medical advice.
- Does it work: 21 meta-analyses
- How much: the dose per kilogram, and the downside of dosing
- When: 60 minutes, depending on the form
- And if I already drink coffee: the myth of tolerance
- Why some people don't respond
- Evening: what six hours is not enough to erase
- The protocol, by weight and by hour
- Frequently asked questions
Does it work: 21 meta-analyses
Eleven systematic reviews, totaling 21 meta-analyses, were included, all of moderate or high methodological quality. In these meta-analyses, caffeine was ergogenic for aerobic endurance, muscle strength, muscle endurance, power, jumping performance, and exercise speed. According to GRADE criteria, the quality of evidence was generally moderate. The effect size appears generally greater for aerobic exercise than for anaerobic exercise. Most individual studies involved young men.
Grgic J, Grgic I, Pickering C, Schoenfeld BJ, Bishop DJ, Pedisic Z. Br J Sports Med 2020;54(11):681-688. DOI: 10.1136/bjsports-2018-100278
A umbrella review is the highest level of evidence synthesis that exists. This one, led by Jozo Grgic in Melbourne, states that caffeine works on almost everything, with two honest caveats: the evidence is of moderate rather than high quality, and it comes mainly from young men. The effect is more pronounced in aerobic endurance than in pure strength.
How much: the dose per kilogram, and the flip side of dosing
Caffeine consistently improves performance at doses of 3 to 6 mg per kilogram of body weight. The minimum effective doses remain uncertain but could be as low as 2 mg per kilogram. Very high doses, for example 9 mg per kilogram, are accompanied by a high incidence of adverse effects and do not appear necessary for the ergogenic effect. The most commonly used timing is 60 minutes before exercise. Interindividual differences, as well as adverse effects on sleep or anxiety, may be attributable to genetic variation in caffeine metabolism and physical and psychological response.
Guest NS, VanDusseldorp TA, Nelson MT, et al. J Int Soc Sports Nutr 2021;18(1):1. DOI: 10.1186/s12970-020-00383-4
| Body Weight | 3 mg/kg, to start | 6 mg/kg, the upper range | 9 mg/kg, dangerous and unnecessary |
|---|---|---|---|
| 55 kg | 165 mg | 330 mg | 495 mg |
| 65 kg | 195 mg | 390 mg | 585 mg |
| 75 kg | 225 mg | 450 mg | 675 mg |
| 85 kg | 255 mg | 510 mg | 765 mg |
| 95 kg | 285 mg | 570 mg | 855 mg |
The range is broad, and the right approach is to start low : 3 mg per kilogram already delivers the effect in most studies, and each milligram above adds more adverse effects than performance gains. The right-hand column is not an option: it's the zone where the ISSN observes frequent adverse effects without benefit, and it's reached quickly through accumulation—two scoops of pre-workout and a coffee are enough to hit it for a 65 kg person.
Caffeine is a widely recognized psychostimulant that has been consumed by humans for a long time. Much remains to be learned about its toxicology, particularly in cases of overdose. This review covers the history of caffeine consumption and its clinical toxicology, its clinical manifestations, its pharmacokinetics and toxicokinetics, its mechanism of action, and management strategies. While high amounts, on the order of several grams, are known to cause toxicity and potentially death, cases of individuals, especially young people, who experienced serious effects and deaths after doses not considered dangerous are concerning and deserve to be studied.
Willson C. Toxicol Rep 2018;5:1140-1152. DOI: 10.1016/j.toxrep.2018.11.002
The key sentence in this review: serious accidents at doses not thought to be dangerous, in young people. The margin between the effective dose and the toxic dose is wide for most people, but it is not the same for everyone, and it narrows when sources add up. The symptoms that signal excess are those in the alert section: tremors, heart palpitations, sudden anxiety, nausea. They are non-negotiable.
When: 60 minutes, depending on the form
Caffeine ingested, in capsule, coffee, or tea, reaches its blood peak in 45 to 60 minutes, and that's the reason for the delay used in almost all trials. The ISSN position specifies that the form changes this delay: caffeine gum, absorbed through the mouth's mucosa, works faster and is taken closer to the effort. For coffee or mate, allow an hour. And the half-life, the time to eliminate half of it, is four to six hours in most adults, which raises the question about the evening.
What if I already drink coffee: the myth of tolerance
Forty trained male endurance cyclists were divided into tertiles according to their daily caffeine consumption: low, 58 mg per day, moderate, 143 mg, high, 351 mg. They completed three simulated time trials after caffeine at 6 mg per kilogram, placebo, or no supplement. Performance was significantly improved with caffeine, 29.92 minutes, compared to 30.81 with placebo and 31.14 with nothing. Covariance analysis revealed no influence of habitual consumption on performance; it did not differ between tertiles. High habitual consumption does not eliminate the benefits of acute supplementation.
Gonçalves LS, Painelli VS, Yamaguchi G, et al. J Appl Physiol 2017;123(1):213-220. DOI: 10.1152/japplphysiol.00260.2017
The title of the University of São Paulo article says it all: dispelling the myth. The idea that you must stop drinking coffee a week before a competition for caffeine to "work again" does not hold up: cyclists at 351 mg per day gained as much as those at 58 mg. No need to quit. But beware the flip side: if you already drink 351 mg per day and add 6 mg per kilogram, you're at 700 mg during the day, and the effect maintains its strength while the risk increases.
Why some don't respond
The response to caffeine varies from person to person, in performance as well as in side effects, and the position identifies the main source: the genetics of metabolism, particularly variants of the CYP1A2 gene that regulate the speed at which the liver eliminates caffeine. Fast metabolizers eliminate it quickly and get the most benefit; slow metabolizers retain it longer, sleep poorly, and become anxious at the same dose. In the São Paulo trial, five to eight cyclists per group of thirteen or fourteen progressed beyond test variation: the majority, not all. If 3 mg per kilogram does nothing for you after three trials, or makes you nervous, caffeine is not your ingredient, and creatine remains.
The evening: what six hours is not enough to erase
This study compared the sleep-disrupting effects of a fixed dose of caffeine, 400 mg, administered 0, 3, and 6 hours before the usual bedtime, compared to placebo, on self-reported sleep at home, also measured by a validated portable sleep monitor. A moderate dose of caffeine at bedtime, 3 hours before, or 6 hours before, in each case had significant effects on sleep disruption. The magnitude of the reduction in total sleep time suggests that caffeine taken 6 hours before bedtime has significant sleep-disrupting effects, and provides empirical support for the recommendation to abstain from any substantial caffeine consumption for at least 6 hours before bedtime.
Drake C, Roehrs T, Shambroom J, Roth T. J Clin Sleep Med 2013;9(11):1195-1200. DOI: 10.5664/jcsm.3170
400 mg is 5.3 mg per kilogram for 75 kg: a standard pre-workout dose. Taken at 5 p.m. for a 11 p.m. bedtime, it measurably shortens the night. Our article on sleep reminds you what two short nights cost. For a session after 5 p.m. with an 11 p.m. bedtime, the choice is binary: caffeine or sleep. Slow metabolizers should allow for even more time.
The protocol, by weight and per hour
Organic yerba mate leaves to infuse, 45 to 60 minutes before a morning or midday session. A strong infusion delivers around 30 to 80 mg of caffeine depending on dosage and steeping time, along with the leaf's polyphenols: an honest approximation of trial doses, not milligram-precise measurement. Not for evening.
See the MateOur matcha is the other infusion source. Creatine, meanwhile, is taken daily and depends neither on timing nor on genes.
Frequently asked questions
Does caffeine really improve performance?
It's the best-documented ingredient in all sports nutrition. An umbrella review published in the British Journal of Sports Medicine examined eleven systematic reviews totaling 21 meta-analyses, all of moderate to high methodological quality. Caffeine is ergogenic for aerobic endurance, strength, muscular endurance, power, jumping, and speed. The quality of evidence is judged moderate. The effect is generally larger for aerobic than anaerobic activities, and most studies involve young men.
What caffeine dose before sport?
The International Society of Sports Nutrition position: 3 to 6 mg per kilogram of body weight. For 60 kg, 180 to 360 mg; for 75 kg, 225 to 450 mg; for 90 kg, 270 to 540 mg. The minimum effective dose is uncertain but could be 2 mg per kilogram. Very high doses of 9 mg per kilogram are accompanied by a high incidence of adverse effects without additional gain. Start at the low end of the range, 3 mg per kilogram, and increase only if well tolerated.
Is excess caffeine dangerous?
Yes. Beyond the effective dose, caffeine causes nervousness, anxiety, trembling, heart palpitations, accelerated heart rate, nausea, and insomnia; the ISSN position notes that at 9 mg per kilogram the incidence of adverse effects is high without performance gain. At even higher doses, clinical toxicology describes heart rhythm disturbances, convulsions, and deaths, documented from several grams onward, but also in young adults, serious accidents at doses not thought to be dangerous, often from the cumulative effect of energy drinks, supplements, and coffee. In a survey of 872 pre-workout users, 54% report adverse effects, including rhythm abnormalities, and 14% double their dose. Palpitations, chest pain, malaise: stop and consult a healthcare provider.
How long before training?
The most commonly used timing in trials is 60 minutes before exercise, because caffeine in capsule or drink form reaches peak blood levels within this window. The ISSN position specifies that the timing depends on the form: caffeine chewing gum, absorbed through the oral mucosa, requires less waiting time. For coffee or yerba mate, allow 45 to 60 minutes.
If I already drink coffee every day, does caffeine still work?
Yes, and a study from the University of São Paulo demonstrated this. Forty trained cyclists were divided into three groups based on their daily consumption—low at 58 mg per day, moderate at 143 mg, and high at 351 mg—and completed a time trial after receiving 6 mg per kilogram of caffeine, a placebo, or nothing. Caffeine improved the time from 30.81 to 29.92 minutes, approximately 3%, and habitual consumption had no influence on this improvement. Heavy coffee drinkers progressed just as much as others.
Why don't some people respond to caffeine?
Because the response varies from person to person, and the ISSN position identifies the causes: the genetics of caffeine metabolism, particularly variants of the CYP1A2 gene that determine how quickly the liver eliminates it, and the individual physical and psychological response. The same factors explain why some people sleep poorly or become anxious with a dose that others tolerate without feeling anything.
Does evening caffeine prevent sleep?
Even six hours before, yes. At the Henry Ford Hospital Sleep Center in Detroit, a fixed dose of 400 mg of caffeine was given double-blind at bedtime, three hours before, or six hours before, versus placebo, with sleep measured at home. All three timings significantly disrupted sleep. The authors recommend avoiding any substantial caffeine at least six hours before bedtime.
How much caffeine in coffee, yerba mate, tea?
This depends greatly on preparation. An espresso contains approximately 60 to 100 mg, a 250 ml cup of filter coffee 80 to 150 mg, a cup of yerba mate or matcha 30 to 80 mg depending on dosage and steeping. To reach 3 mg per kilogram, or 210 mg for 70 kg, you need two to three espressos or a strong yerba mate infusion, with an uncertainty of several tens of milligrams. Studies use pure caffeine dosed to the milligram.
What to remember about caffeine before sport?
That it is the best-documented ingredient in sports, with 21 meta-analyses. That the dose is 3 to 6 mg per kilogram, 60 minutes before, starting at the low end. That drinking coffee daily does not block its effect. That the response varies according to genetics. That 400 mg six hours before bedtime still shortens your night. And that excess is dangerous: anxiety, palpitations, heart rhythm disturbances, and documented deaths at high doses or from cumulative intake.
Sources
The studies cited below were identified via PubMed.
- Guest NS, VanDusseldorp TA, Nelson MT, et al. International Society of Sports Nutrition position: caffeine and exercise performance. Journal of the International Society of Sports Nutrition, 2021;18(1):1. DOI
- Grgic J, Grgic I, Pickering C, Schoenfeld BJ, Bishop DJ, Pedisic Z. Wake up and smell the coffee: caffeine supplementation and exercise performance, an umbrella review of 21 published meta-analyses. British Journal of Sports Medicine, 2020;54(11):681-688. DOI
- Gonçalves LS, Painelli VS, Yamaguchi G, et al. Dispelling the myth that habitual caffeine consumption influences the performance response to acute caffeine supplementation. Journal of Applied Physiology, 2017;123(1):213-220. DOI
- Drake C, Roehrs T, Shambroom J, Roth T. Caffeine effects on sleep taken 0, 3, or 6 hours before bedtime. Journal of Clinical Sleep Medicine, 2013;9(11):1195-1200. DOI
- Willson C. Clinical toxicology of caffeine: a review and case study. Toxicology Reports, 2018;5:1140-1152. DOI
