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Acute caffeine supplementation may slightly improve maximal strength and may benefit muscular endurance in some protocols in female participants, but certainty of evidence is low or very low for most outcomes.

A systematic review and three-level meta-analysis of 24 studies (23 in quantitative synthesis, 107 effect sizes) found a small mean effect of caffeine on maximal strength (g = 0.17, 95% CI 0.06 to 0.29; low GRADE) and a larger mean effect on muscular endurance (g = 0.54, 95% CI 0.06 to 1.02; low GRADE), but the latter had a wide prediction interval indicating low reproducibility. Movement speed showed a small, uncertain estimate (g = 0.13; CR2 p = 0.072; very low GRADE), and other domains were not pooled due to insufficient clusters.

Last updated: Aug 17, 2026•0 RCTs•1 Meta-analyses•📖 Read as article →

Evidence Score

Evidence Score49/100
Human RCT☆☆☆☆☆
Meta-analysis★★★☆☆
Mechanism★★★★★
Safety★★★★☆
Confidencelow

Study Evidence

Study 1. Acute caffeine supplementation and resistance exercise performance in female participants: a systematic review and three-level meta-analysis.

observational

Liang L, Chen M, Qi B · Frontiers in physiology (2026)

Participants: N/A
Duration: N/A
Intervention: Acute caffeine supplementation (dose-defined) before resistance exercise, compared to placebo.
Outcome: Maximal strength, muscular endurance, movement speed, functional strength, functional endurance, and total load.
Effect Size: Maximal strength: g = 0.17 (95% CI 0.06 to 0.29); Muscular endurance: g = 0.54 (95% CI 0.06 to 1.02)
Population: Female participants (or independently extractable female subgroups) in randomized, placebo-controlled trials.

Result:

PubMed: 42591203DOI: 10.3389/fphys.2026.1892370

Mechanism Graph

Caffeine is ingested acutely before resistance exercise.
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Caffeine acts as an adenosine receptor antagonist, reducing perceived exertion and pain.
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This may enhance neural drive and muscle contractility.
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Result: Slight improvements in maximal strength and potentially larger improvements in muscular endurance in some protocols.

Limitations

  • ⚠Certainty of evidence was low or very low for most outcomes due to risk of bias and imprecision.
  • ⚠Prediction intervals were wide, indicating limited reproducibility across protocols.
  • ⚠Only three study clusters were available for movement speed, making cluster-robust inference uncertain.
  • ⚠Functional strength, functional endurance, and total load domains had too few clusters to pool, so only descriptive summaries were possible.

Frequently Asked Questions

Does caffeine improve resistance exercise performance in women?▼

The meta-analysis found a small improvement in maximal strength and a larger but less reproducible improvement in muscular endurance, but the certainty of evidence is low.

What is the effect size of caffeine on maximal strength in women?▼

The mean effect size was g = 0.17 (95% CI 0.06 to 0.29), indicating a small effect.

Is caffeine recommended for women before resistance training?▼

Current evidence does not support strong recommendations by dosage, age, resistance load, menstrual cycle phase, hormonal status, or habitual caffeine intake due to low certainty.

What outcomes were measured in the meta-analysis?▼

Outcomes included maximal strength, muscular endurance, movement speed, functional strength, functional endurance, and total load.

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References

  1. 1.Liang L, Chen M, Qi B. "Acute caffeine supplementation and resistance exercise performance in female participants: a systematic review and three-level meta-analysis.." Frontiers in physiology, 2026. PMID: 42591203 DOI: 10.3389/fphys.2026.1892370
Disclaimer: This content is for educational purposes only and is not medical advice. Evidence scores reflect the quality and quantity of available research, not clinical recommendations. Always consult a healthcare professional before starting any supplement or intervention.