The Claim
In female handball players aged 18–19 with low habitual caffeine consumption, ingestion of caffeine at doses of 3 mg/kg or 6 mg/kg has no effect on perceived exertion during high-intensity exercise, irrespective of time of day.
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.
For young female handball players who rarely consume caffeine, taking 3 or 6 milligrams of caffeine per kilogram of body weight does not change how hard they feel they are working during intense exercise, no matter whether it is morning or evening.
See the scientific wording
In low-caffeine-consuming female handball players aged 18–19, caffeine ingestion at 3 mg/kg or 6 mg/kg does not alter perceived exertion during high-intensity exercise, regardless of time of day, suggesting its ergogenic effects are not mediated by reduced fatigue perception.
Caffeine blocks natural fatigue signals in the brain, allowing muscles to work harder without changing how tired the person feels. The brain sends stronger signals to the muscles, increasing force and speed during exercise, but the feeling of effort stays the same.
What the research says
1 studyFor young female athletes who don’t usually drink caffeine, taking caffeine before exercise makes them perform better in the morning—but they still feel just as tired. So, caffeine helps their body work harder, but not because they feel less fatigued.
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.