Can physical performance be improved by stimulating the brain with low-intensity transcranial electrical stimulation? Is this a new form of sports performance enhancement that could be considered neuro-doping?
The answer to these questions, according to a review made by scientists from the Mind, Brain and Behavior Research Center (CIMCYC; Daniel Sanabria Lucena and Rafael Román Caballero) with collaborators from the Autonomous University of Madrid (Miguel Á. Vadillo) and the University of Lausanne (Switzerland; Darías Holgado) suggests that at this time there is no scientific evidence available to confirm the efficacy of these brain electrical stimulation devices to improve sports performance.
The absence of evidence, the authors clarify, does not imply the absence of a possible benefit of brain stimulation, but rather that this improvement is not scientifically supported. The crucial role played by the brain in human behavior and, therefore, in physical performance, has prompted numerous scientific studies in the field of sports science to investigate, for some years now, whether stimulation of the brain with very low intensity electrical current can improve physical performance.
The apparently positive results of this research have led to the commercialization of low-cost, easy-to-use devices that promise significant improvements in physical performance. At the same time, scientific and informative articles warning of the possibility of a new form of doping, the aforementioned neuro-doping.
When drawing conclusions, this review has corrected the result for publication bias, the tendency to favor the publication of positive results over null results. Another analysis showed that the final result of the meta-analyses depended on a large extent on the decisions made when analyzing the data, such as the formula used to calculate the effect size.
This result joins recent evidence from the same research group* on the presence of biases in research on the cognitive benefits of physical exercise and the absence of conclusive results.
This study, however, does not close the door on the possibility that brain stimulation can improve physical performance. For example, by developing better hypotheses and methodologies, the potential benefits of multiple sessions of low-intensity brain stimulation, its systematic application during exercise, and its use as a post-exercise recovery tool could be investigated. Ideally, this line of work should include pre-registered studies published in public repositories, guaranteeing open access to all data.
* Ciria, L.F., Román-Caballero, R., Vadillo, M.A. et al. An umbrella review of randomized control trials on the effects of physical exercise on cognition. Nat Hum Behav 7, 928–941 (2023). https://doi.org/10.1038/s41562-023-01554-4
Reference
Holgado, D., Sanabria, D., Vadillo, M. A., & Román-Caballero, R. (2024). Zapping the brain to enhance sport performance? An umbrella review of the effect of transcranial direct current stimulation on physical performance. Neuroscience & Biobehavioral Reviews, 164, 105821. https://doi.org/10.1016/j.neubiorev.2024.105821
Contact:
Rafael Román Caballero - @email