Transcranial direct current stimulation (tDCS): A new, (still) legal form of "neurodoping" in sports?

Transcranial direct current stimulation (tDCS) has emerged as a widely accessible, noninvasive technique capable of modulating cortical excitability. A rapidly expanding body of sports-science literature suggests that it can produce modest but measurable gains in endurance, strength, skill acquisition, and perceived exertion. This editorial reviews the physiological mechanisms underlying tDCS, evaluates the evidence for its ergogenic effects, and situates the technology within the broader framework of "neurodoping". Applying the 2021 World Anti-Doping Agency (WADA) Code, I argue that tDCS already satisfies 2 of the 3 criteria for prohibition - namely, potential performance enhancement and violation of the spirit of sport - while failing the 3rd criterion, as standard protocols pose minimal health risk. This editorial also considers practical and ethical counterarguments to a ban, including tDCS's low cost, relative safety, requirement for continued training effort, and the near-impossibility of detection or enforcement. Drawing parallels with accepted performance aids such as mindfulness, nutrition and altitude tents, this editorial concludes that outright prohibition could drive use underground and impede open scientific scrutiny. Instead, it advocates rigorous long-term safety monitoring, transparent research, and nuanced policy development that distinguishes therapeutic from performance applications. Ultimately, it frames tDCS as a "still-legal" yet ethically contested innovation at the frontier of sports technology, urging stakeholders to balance principles of fair play with scientific evidence as the debate over neurodoping continues to evolve.