The Claim
Caffeine ingestion during high-intensity endurance exercise leads to an increase in perceived exertion in adolescent athletes with the ACE II genotype and a decrease in perceived exertion in those with the ACE 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, 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.
See the scientific wording
Perceived exertion during high-intensity endurance exercise increases with caffeine in adolescent athletes with the ACE II genotype but decreases in those with the DD genotype, indicating a genotype-dependent effect on the subjective experience of effort.
In people with the ACE II gene version, caffeine lets them exercise longer before getting tired, which builds up more waste products in their muscles; these waste products send stronger signals to the brain that the effort is harder. In people with the ACE DD gene version, caffeine blocks signals that make exercise feel tiring, so they feel less effort without exercising longer.
What the research says
1 studyWhen teen athletes took caffeine before a tough workout, those with the II gene felt like they were working harder, while those with the DD gene felt like it was easier — showing that your genes change how caffeine affects how hard you feel you're working.
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.