Caffeine and Cognitive Functions in Sports: A Systematic Review and Meta-Analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized crossover trials
PubMed 33800853 · doi:10.3390/nu13030868
What was done
A systematic review and meta-analysis following PRISMA guidelines evaluated the impact of caffeine on cognitive performance in sports. Databases searched included Medline/PubMed and Web of Science for English-language records from August 1999 to March 2020. Inclusion was restricted to randomized crossover trials comparing caffeine (drinks, capsules, energy bars, or gum) against identical placebo across any age, gender, or training status. Thirteen studies assessing objective or self-reported cognitive measures were identified, and five were included in the meta-analysis.
What was found
The abstract reports no numerical effect sizes, test statistics, or confidence intervals. In the pooled meta-analysis of five studies, caffeine had statistically significant impacts only on attention, accuracy, and speed. Across the thirteen qualitative studies, low-to-moderate doses before or during exercise were reported to improve self-reported energy, mood, and attention, with inconsistent results for simple reaction time, choice reaction time, memory, or fatigue.
Why it matters
It synthesizes controlled trial evidence demonstrating that caffeine enhances specific cognitive domains (speed, accuracy, and attention) during athletic activity, clarifying that not all cognitive metrics benefit equally.
Limits
The meta-analysis included only five studies, and the abstract reports no exact participant numbers or quantitative effect sizes. Heterogeneous delivery methods (capsules, gum, bars, liquids) and varying cognitive assessment protocols limit direct comparability.
Cited by
- supports Scientific research consistently demonstrates that caffeine acts as a nootropic cognitive enhancer.