The Claim

The ergogenic effect of caffeine on vertical jumping performance in females is significantly greater during the follicular phase of the menstrual cycle (Hedges' g = 0.52) than during other phases (Hedges' g = 0.21–0.31), indicating that menstrual phase moderates caffeine's impact on explosive power.

Source: Moderators of Caffeine's Effects on Jumping Performance in Females: A Systematic Review and Meta-Analysis.

What the research says

Supports is higher

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

Supports
45score
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.

Quantitative
1 study reviewed
In plain English

In women, caffeine improves vertical jump performance more during the follicular phase of the menstrual cycle than during other phases.

See the scientific wording

The ergogenic effect of caffeine on vertical jumping performance in females is significantly greater during the follicular phase of the menstrual cycle (Hedges' g = 0.52) compared to other phases (g = 0.21–0.31), suggesting menstrual phase may moderate caffeine's impact on explosive power.

Why this might work

During the first part of the menstrual cycle, higher estrogen levels make the brain more responsive to caffeine, which turns up the signal from the brain to the leg muscles, making them fire harder and faster when jumping.

Suggested mechanismbased on 1 study

What the research says

1 study
  1. Study: Moderators of Caffeine's Effects on Jumping Performance in Females: A Systematic Review and Meta-Analysis.

    This study found that caffeine helps women jump higher, and it works best during the first half of their menstrual cycle—like how some medicines work better at certain times.

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

Fit Body Science verdict — we translate health claims into clear verdicts backed by peer-reviewed research.

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