Can physical performance be improved by stimulating the brain with low-intensity electrical current? Are we witnessing the emergence of a new form of sport performance enhancement that could be considered neurodoping? The answer to these questions, according to a study carried out by scientists from the UGR’s Mind, Brain and Behaviour Research Centre (CIMCYC), in collaboration with the Autonomous University of Madrid and the University of Lausanne (Switzerland), is that there is currently no scientific evidence to confirm the efficacy of these transcranial electrical stimulation devices in improving athletic performance.
The authors are careful to point out that this lack of conclusive evidence does not mean that brain stimulation cannot improve physical performance, only that this improvement has not been scientifically proven. The research, published in the scientific journal Neuroscience & Biobehavioral Reviews, involved the review and re-analysis of 50 primary studies and nine meta-analyses.
Given the crucial role that the brain plays in human behaviour, and therefore in physical performance, there have been a number of scientific studies in recent years in the field of sport sciences that have investigated whether stimulating the brain with very low-intensity electrical current can improve physical performance. The apparently positive results of these investigations have led to the commercialisation of low-cost and easy-to-use devices that promise significant improvements in physical performance. At the same time, they have given rise to scientific and informative articles warning of the possibility of a new form of doping, the aforementioned neurodoping.
When drawing their conclusions, the CIMCYC researchers corrected the results for publication bias, the tendency to favour the publication of positive results over null results. Another analysis showed that the final results of the meta-analyses were strongly influenced by the decisions made when analysing the data, such as the formula used to calculate the size of the effect. These findings add to recent evidence from the same research group about the presence of bias in research on the cognitive benefits of physical exercise and the lack of conclusive results. The literature on brain stimulation and physical performance includes many low-quality studies, mainly due to their low statistical power, publication bias, and meta-analytic results that are largely dependent on the decisions their authors make when analysing the available empirical evidence.
However, the study does not rule out the possibility that brain stimulation can improve physical performance. For example, by developing better hypotheses and methodologies, further research could be conducted on 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. Ideally, this line of research should include preregistered studies published in public repositories that also guarantee open access to all data.
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.
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