The Claim

In low-caffeine-consuming female handball players aged 18–19, ingestion of 6 mg/kg of caffeine 60 minutes before morning exercise improves short-term maximal performance in countermovement jumps, agility, and repeated sprints more than ingestion of 3 mg/kg of caffeine at the same time, with effect sizes ranging from 2.5% to 3.8%, while ingestion of either dose 60 minutes before evening exercise provides no improvement in these performance metrics.

Source: Effects of Different Caffeine Dosages on Maximal Physical Performance and Potential Side Effects in Low-Consumer Female Athletes: Morning vs. Evening Administration

What the research says

Supports is higher

Support is ahead, but a single strong opposing study can change this.

Supports
68score
Challenges
0score

These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.

Cause and effect
1 study reviewed
In plain English

For young female handball players who consume little caffeine, taking 6 mg/kg of caffeine before morning exercise results in greater improvements in jump height, agility, and sprint speed than taking 3 mg/kg, but neither dose improves performance when taken before evening exercise.

See the scientific wording

In low-caffeine-consuming female handball players aged 18–19, ingesting 6 mg/kg of caffeine 60 minutes before morning exercise likely improves short-term maximal performance in countermovement jumps, agility, and repeated sprints more than 3 mg/kg, with effect sizes ranging from 2.5% to 3.8%, while evening ingestion of either dose provides no performance benefit.

Why this might work

Caffeine blocks natural sleep signals in the brain, making the brain more active and telling muscles to work harder, which makes jumping, sprinting, and changing direction faster — but only in the morning when the brain is naturally less alert.

Verified mechanismbased on 1 study

What the research says

1 study

  1. Study: Effects of Different Caffeine Dosages on Maximal Physical Performance and Potential Side Effects in Low-Consumer Female Athletes: Morning vs. Evening Administration

    For young female athletes who don’t usually drink caffeine, taking a higher dose in the morning helps them jump higher, run faster, and change direction quicker—but taking the same doses at night doesn’t help at all.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies

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