The Study
ACE gene polymorphisms (rs4340) II and DI are more responsive to the ergogenic effect of caffeine than DD on aerobic power, heart rate, and perceived exertion in a homogeneous Brazilian group of adolescent athletes
This study gave teens caffeine or a fake pill and saw how well they ran, then checked if their genes made a difference. It shows that for these specific teens, caffeine helped some more than others—but it doesn’t prove caffeine works this way for everyone else.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Some teens have a gene version that makes caffeine help them run farther and breathe better during sports, while others don't get much benefit.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 558 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — for teens with the right gene, caffeine can make a big difference in endurance, like running nearly 300 meters farther in a high-intensity test.
- 2Teens with the II or DI gene version ran 160–286 meters farther and had 1.1–1.4 mL·kg⁻¹·min⁻¹ higher oxygen use after caffeine.
- 3Teens with DD gene ran only 31 meters farther.
- 484% of II teens improved with caffeine; only 33% of DD teens did.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Brazilian Journal of Medical and Biological Research
Year
2024
Authors
H. Spineli, M. Santos, D. Almeida, D. Gitai, M. Silva-Cavalcante, P. Balikian, T. Ataide-Silva, A. Marinho, F. Sousa, G. Araujo
Related Content
Claims (6)
In adolescent athletes with the ACE II genotype, consistent caffeine consumption is linked to higher endurance performance and aerobic power only when caffeine is consumed shortly before exercise, and this effect depends on their genetic profile.
In adolescent male athletes of Brazilian descent, consuming 6 mg of caffeine per kilogram of body weight increases endurance performance and VO2max only in those with the ACE gene I allele (DI or II genotypes), not in those with the DD genotype.
Among adolescent male athletes, those with the ACE DD genotype show a lower rate of endurance performance improvement after consuming caffeine compared to those with the DI or II genotype.
In adolescent athletes, caffeine changes how hard exercise feels during high-intensity endurance activity, but the effect depends on their ACE gene variant: it makes effort feel harder for those with one variant and easier for those with another.
In adolescent athletes, consuming caffeine before high-intensity endurance exercise raises heart rate if they have the ACE I allele (DI or II genotypes), but does not raise heart rate if they have the DD genotype.
Caffeine makes people feel like they are working harder during exercise and increases their motivation to work out, but it does not cause muscles to grow unless the physical load on the muscles is increased.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.