Wake up and smell the coffee: caffeine supplementation and exercise performance-an umbrella review of 21 published meta-analyses.
Level 1 - systematic review of randomized trials
Umbrella review of published systematic reviews and meta-analyses of randomized trials
PubMed 30926628 · doi:10.1136/bjsports-2018-100278
What was done
Umbrella review searching 12 electronic databases to systematically review, summarize, and appraise published meta-analyses evaluating the effects of caffeine ingestion on exercise performance. Methodological quality of the included reviews was appraised with the AMSTAR 2 checklist, and quality of evidence was graded using GRADE criteria.
What was found
Eleven reviews containing a total of 21 meta-analyses were included, all judged to be of moderate or high methodological quality. Caffeine was ergogenic for aerobic endurance, muscle strength, muscle endurance, power, jumping performance, and exercise speed, with effects appearing generally greater for aerobic versus anaerobic exercise. No specific numerical effect sizes or confidence intervals were reported in the abstract. When evaluating 95% prediction intervals, not all analyses provided a definite direction of effect. GRADE evidence certainty was generally moderate, with some outcomes rated low to very low.
Why it matters
This umbrella review synthesizes high-level meta-analytic evidence confirming caffeine's broad ergogenic effects across multiple exercise modalities while highlighting the areas where evidence quality remains moderate or low.
Limits
The abstract reports no numerical effect sizes, sample sizes, or confidence intervals. Prediction intervals show that positive effects are not guaranteed across all contexts. Primary studies within the analyzed meta-analyses predominantly studied young men, limiting generalizability to women, middle-aged, and older adults.
Cited by
- supports Caffeine acts as an ergogenic aid that enhances athletic performance.