Placebo effects of caffeine on sport performance: a systematic review and meta-analysis.
6 affiliations
- 1Department of Sport & Exercise, Canterbury Christ Church University, Canterbury, United Kingdom.
- 2Applied Physiology and Nutrition Research Group - School of Physical Education and Sport and Faculdade de Medicina FMUSP, Universidade de São Paulo, São Paulo, Brazil.
- 3Center of Lifestyle Medicine, Faculdade de Medicina FMUSP, Universidade de São Paulo, São Paulo, Brazil.
- 4Erasmus University Rotterdam, Department of Medical Informatics, Rotterdam, The Netherlands.
- 5Postgraduate Program in Biosciences and Human Health, Minas Gerais State University, Divinopolis, Minas Gerais, Brazil.
- 6Federal University of Juiz de Fora, Department of Physiology, Juiz de Fora, Sao Paulo, Brazil.
Abstract
Background
A body of research has shown that deceptively administering a placebo described as caffeine can significantly improve sport performance. We aimed to synthesize and estimate the effect size of the deceptive administration of a placebo described as caffeine on sport performance outcomes (e.g. bench press, cycling time-trial, repeated sprint).Methods
We searched for studies sampling healthy adults from database creation to July 2026. The standardized mean difference (d) between placebo caffeine and baseline was calculated and Cochrane's risk of bias assessment was used.Results
Seventeen studies were included. Nine studies were judged to be of high-risk of bias and eight unclear. Random-effect models revealed a small-to-moderate effect of placebo caffeine benefiting performance (d = 0.49, 95% CI = 0.28 to 0.69) and meta-regressions indicated that pooled effects were more likely to be greater when researchers were blinded (b = 0.52 ± 0.24, 95% CI = 0.01 to 0.99) and in studies sampling more males (b = -0.93 ± 0.38, 95% CI = -1.68 to -0.19).Discussion
Data highlight that placebo effects of caffeine can significantly affect sport performance with a pooled effect estimate suggesting a small-to-moderate effect. However, as per the GRADE assessment, the overall quality of evidence was low. As such, given the high risk of bias across all studies and the variation in confidence interval, stronger research designs are needed to examine placebo effects of caffeine, whereby researchers are blinded to treatment administration and allocation concealment. No funding was received for the review and the protocol can be found here: doi: 10.17605/OSF.IO/W8KY6.
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BibTeX
@article{hurst2026placebo,
title = {{Placebo effects of caffeine on sport performance: a systematic review and meta-analysis.}},
author = {Philip Hurst and Janina Hanssen and Felipe Marticorena and Lieke Schiphof-Godart and Hiago L R Souza and Moacir Marocolo and Bryan Saunders},
journal = {Journal of the International Society of Sports Nutrition},
year = {2026},
month = oct,
doi = {10.1080/15502783.2026.2747142},
url = {https://europepmc.org/article/MED/42897966},
note = {CC BY},
}
RIS
TY - JOUR
TI - Placebo effects of caffeine on sport performance: a systematic review and meta-analysis.
AU - Philip Hurst
AU - Janina Hanssen
AU - Felipe Marticorena
AU - Lieke Schiphof-Godart
AU - Hiago L R Souza
AU - Moacir Marocolo
AU - Bryan Saunders
PY - 2026
DA - 2026/10/20
JO - Journal of the International Society of Sports Nutrition
DO - 10.1080/15502783.2026.2747142
UR - https://europepmc.org/article/MED/42897966
AB - Background A body of research has shown that deceptively administering a placebo described as caffeine can significantly improve sport performance. We aimed to synthesize and estimate the effect size of the deceptive administration of a placebo described as caffeine on sport performance outcomes (e.g. bench press, cycling time-trial, repeated sprint).Methods We searched for studies sampling healthy adults from database creation to July 2026. The standardized mean difference (d) between placebo caffeine and baseline was calculated and Cochrane's risk of bias assessment was used.Results Seventeen studies were included. Nine studies were judged to be of high-risk of bias and eight unclear. Random-effect models revealed a small-to-moderate effect of placebo caffeine benefiting performance (d = 0.49, 95% CI = 0.28 to 0.69) and meta-regressions indicated that pooled effects were more likely to be greater when researchers were blinded (b = 0.52 ± 0.24, 95% CI = 0.01 to 0.99) and in studies sampling more males (b = -0.93 ± 0.38, 95% CI = -1.68 to -0.19).Discussion Data highlight that placebo effects of caffeine can significantly affect sport performance with a pooled effect estimate suggesting a small-to-moderate effect. However, as per the GRADE assessment, the overall quality of evidence was low. As such, given the high risk of bias across all studies and the variation in confidence interval, stronger research designs are needed to examine placebo effects of caffeine, whereby researchers are blinded to treatment administration and allocation concealment. No funding was received for the review and the protocol can be found here: doi: 10.17605/OSF.IO/W8KY6.
SN - 1550-2783
ER -