The Claim

Acute ingestion of 5 mg/kg of caffeine before resistance exercise increases the number of repetitions performed to failure at both 90% and 50% of one-repetition maximum (1RM) in young, healthy, resistance-trained individuals.

Source: Effects of acute caffeine ingestion on muscle strength, muscular endurance, rating of perceived exertion, and pain perception during strength exercise until the failure

What the research says

Supports is higher

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

Supports
48score
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

Taking 5 mg of caffeine per kilogram of body weight before a weightlifting session increases the number of repetitions a person can complete to muscle failure at both high and moderate weights.

See the scientific wording

Acute ingestion of 5 mg/kg of caffeine before resistance exercise significantly increases the number of repetitions performed to failure at both 90% and 50% of one-repetition maximum (1RM) in young, healthy, resistance-trained individuals, suggesting caffeine enhances muscular endurance under high-intensity and moderate-intensity conditions.

Why this might work

Caffeine stops a chemical in the brain and muscles from signaling tiredness, so the body keeps pushing harder before stopping, allowing more repetitions before exhaustion.

Supported mechanismbased on 1 study

What the research says

1 study

  1. Study: Effects of acute caffeine ingestion on muscle strength, muscular endurance, rating of perceived exertion, and pain perception during strength exercise until the failure

    Taking a caffeine pill before lifting weights helped people do more reps before getting too tired, whether they were lifting heavy or moderate weights.

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.