You thought that pre-workout cup was sharpening your sprints. In a new crossover trial of national-level combat sports athletes, one to two cups' worth of caffeinated coffee did not improve repeated sprint performance at all. Before you toss the espresso machine, though, the details matter a lot.
The Headline Finding: Nothing Moved
A team led by Birol and colleagues, publishing in Scientific Reports (DOI: 10.1038/s41598-026-72577-w, trial registration NCT07596511), tested whether low-dose caffeine delivered as ordinary coffee changes repeated sprint performance and the body's energy system contributions.
The result: no statistically significant differences between conditions in any performance variable (all p > 0.05). That covers peak power, mean power, fatigue index, perceived exertion, delta lactate and peak heart rate. The estimated contributions from the aerobic, glycolytic and phosphagen systems did not differ significantly either.
How the Study Was Built
The design is solid, and it is worth knowing exactly what was done:
- Participants: 15 national-level male combat sports athletes (average age 20.4 years, body mass 68.1 kg)
- Design: double-blind, placebo-controlled, randomized crossover
- Sessions: three, spaced 48 hours apart
- Conditions: coffee providing 1.5 mg/kg caffeine, coffee providing 3 mg/kg caffeine, and decaffeinated coffee as the placebo
- Test: a repeated sprint protocol on a cycle ergometer, started one hour after drinking the coffee
No capsule condition was included, so this was not a coffee-versus-capsule comparison. It asked a narrower question: what does low-dose caffeinated coffee do compared with decaf?
The Dose Math: What "Low Dose" Looks Like in Your Mug
For the average athlete here (68.1 kg), the doses work out to roughly:
- 1.5 mg/kg ≈ 100 mg caffeine
- 3 mg/kg ≈ 200 mg caffeine
That is about one to two cups of coffee, depending on how strong you brew it. In other words, it is a realistic morning-routine or pre-session dose rather than an exotic lab protocol, which is what makes the study relevant to everyday athletes.
Why Other Studies Look So Different
Much of the caffeine-and-performance literature has used anhydrous caffeine capsules, typically at 3 to 13 mg/kg, and doses of 3 mg/kg and above generally show ergogenic effects. Capsules deliver a precise, standardized dose. Coffee is a more variable delivery system, and the authors point out that little is known about doses of 3 mg/kg or below when taken as coffee, even though that is what athletes actually drink.
So the study is not contradicting the capsule literature. It is probing a gap: the low end of the dose range in the form people really use.
The Numbers Behind the Null
Effect sizes for performance variables were tiny (partial eta squared ≤ 0.01). That means caffeine explained essentially none of the variation in sprint outcomes in this group.
The estimated energy system contributions showed medium-to-large effect sizes, but they were not statistically significant. With only 15 athletes, that pattern is hard to interpret. It could be noise, or it could hint at something a bigger study would detect. It should not be read as a real effect.
Caveat: This Is Not Proof That Caffeine Fails
This is a small null result, and a few limits are worth keeping in mind:
- Sample size: 15 athletes limits statistical power. A null result here does not prove there is no effect.
- Population: all participants were young, male, national-level combat athletes. The authors call for larger samples that include women and other training levels.
- Single protocol: one cycle-based repeated sprint test, one timing window (one hour after intake).
- Dose range: the 3 mg/kg condition sits at the very bottom of the range where capsule studies usually report benefits.
What This Means for You
If you want a measurable performance effect: the broader evidence base supports roughly 3–6 mg/kg caffeine taken 30–60 minutes before exercise. For a 68 kg athlete, that is about 200–400 mg. This study's 3 mg/kg condition sits at the lower edge of that window, and it did not move the needle in this sample.
Dose and timing:
- Calculate your dose by body mass rather than by "cups," since coffee strength varies a lot.
- If you rely on coffee, remember that its caffeine content is less predictable than a labeled capsule or tablet.
- Test any dose in training before using it on competition day.
Who it may be for:
- Athletes who want a reliable, quantifiable ergogenic effect and are willing to dose by body weight.
- Anyone who enjoys coffee for alertness and focus. That benefit was not what this study measured, so it is not ruled out.
Who should be cautious or skip it:
- Habitual high-intake users: regular heavy caffeine consumers may find a modest dose does little, and they should be realistic about what a cup is doing for them.
- Poor sleepers or evening trainers: a performance edge is not worth losing sleep, which hurts recovery and next-day training. Caffeine taken late can undermine the very adaptations you are training for.
- Those sensitive to jitters, anxiety or heart rate effects: higher doses raise the odds of side effects.
The Bottom Line
In 15 elite fighters, 100 and 200 mg of caffeine from coffee did not improve repeated sprint performance or change estimated energy system contributions compared with decaf. That is a useful reality check on the idea that any cup of coffee automatically boosts sprints, but it is a small study and not a verdict on caffeine. If you want a true ergogenic effect, the stronger evidence points to higher, weight-based doses taken 30–60 minutes beforehand. If you simply love your coffee for alertness and routine, this study gives you no reason to stop.
