The Claim
Acute caffeine ingestion increases heart rate during high-intensity endurance exercise in adolescent athletes who carry the ACE I allele (DI or II genotypes), but does not increase heart rate in those with the DD genotype.
What the research says
Supports is higher
Support is ahead, but a single strong opposing study can change this.
These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.
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.
See the scientific wording
Acute caffeine ingestion increases heart rate during high-intensity endurance exercise in adolescent athletes with ACE I allele genotypes (DI and II), but not in those with the DD genotype, suggesting genotype-dependent modulation of cardiovascular response to caffeine.
People with the ACE I allele have more slow-twitch muscle fibers that use oxygen efficiently. When they take caffeine before intense exercise, the caffeine blocks signals that normally calm the nervous system, making the brain and heart work harder. This causes the heart to beat faster and the body to keep going longer, which increases stress on the muscles and triggers more adrenaline. The longer exercise time and higher adrenaline levels together make the heart beat even faster than in people without the I allele.
What the research says
1 studyWhen young athletes with certain gene versions (DI or II) drink caffeine before a tough workout, their heart beats faster than when they don’t—this doesn’t happen in athletes with another gene version (DD). The study found this exact pattern.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.