The Claim

In resistance-trained women, acute ingestion of caffeine at a dosage of 3 mg/kg increases countermovement jump height by 3.1% in the morning and by 1.6% in the afternoon, partially restoring afternoon performance levels, while having no effect on bench press throw peak velocity, maximal strength, or strength-endurance.

Source: Caffeine ingestion attenuates diurnal variation of lower-body ballistic performance in resistance-trained women

What the research says

Supports is higher

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

Supports
37score
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 who regularly train with weights, taking 3 mg of caffeine per kilogram of body weight before testing increases vertical jump height in the morning by 3.1% and in the afternoon by 1.6%, but does not change peak speed, maximum strength, or endurance during bench press throws.

See the scientific wording

In resistance-trained women, acute caffeine ingestion (3 mg/kg) increases countermovement jump height by 3.1% in the morning and 1.6% in the afternoon, partially restoring performance to afternoon levels, but has no effect on bench press throw peak velocity, maximal strength, or strength-endurance.

Why this might work

Caffeine blocks a chemical in the brain that slows down nerve signals, allowing the brain to send stronger signals to the leg muscles during quick jumps, making them contract faster and harder without affecting other muscles used in lifting or throwing.

Supported mechanismbased on 1 study

What the research says

1 study
  1. Study: Caffeine ingestion attenuates diurnal variation of lower-body ballistic performance in resistance-trained women

    This study found that when women who lift weights take a moderate dose of caffeine before exercising in the morning, they can jump higher—almost as high as they do in the afternoon. But it doesn’t help them lift heavier weights or throw the bench press faster.

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.

Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.