It’s that time of the year again, the glorious overlap of football, baseball, and hockey. These athletes have spent years practicing and working on skill acquisition to get to this point. If you’re like me you’re quickly humbled by the amount of talent and skill these players demonstrate on a weekly basis. Nearly all professional athletes have such good muscle memory that every throw, catch, check, or swing of the bat is completely dialed in. Given the topic we figured we might talk about a largely studied area of tDCS; the use of brain stimulation to improve aspects of motor control. Stimulation of the motor cortex was one of the first widely accepted protocols in early tDCS research and was used for both healthy individuals as well as those affected by illnesses such as stroke, Parkinson’s Disease, or traumatic brain injury. There are a number of studies that have demonstrated that stimulation of both the right and left motor cortex improves reaction time and accuracy of specific motor tasks [1,2]. Studies like these have demonstrated the huge potential for tDCS in stroke rehabilitation, and more recently stimulation of the motor cortex has been used to enhance fine motor skills in healthy people.
This stimulation has the ability to greatly improve motor skill acquisition. One study showed that those who received real stimulation for 20 minutes a day over 5 consecutive days increased skill acquisition considerably more than those who received sham stimulation.  Even more impressive was that after 3 months without any practice or intervention those who received stimulation were still significantly better than those who had not. Since there have been numerous studies demonstrated enhancement of simple motor tasks more recent papers have examined the possibility that tDCS over the motor cortex could help to improve more complex motor tasks or motor tasks more translatable to real-world activities. One study looked at the use of stimulation to improve the fine motor skills of pianists. They found that there was a significant improvement in players who were deemed beginner musicians but little improvements in expert musicians. With the possibility that tDCS could be used to improve real world motor tasks also comes the implication that this technology could be used not just for musicians but also for athletes.
Now we’ve come full circle. If tDCS really becomes the technology of the future what are the ethical guidelines for its use? There has been plenty of controversy about the use of performance enhancing drugs in major league sports so what about brain stimulation? I’ve had a number of people ask me about the potential for cheating and how these devices might be regulated, but personally I think that you won’t find many professional athletes using tDCS because it won’t help them. You remember that tDCS is important for learning new motor skills but it may actually be detrimental for skills that are already dialed in. As a follow-up study to the use of tDCS for musicians the study was again run with untrained and highly skilled pianists. The study demonstrated a ceiling effect, meaning that the unskilled pianists showed vast improvements in skill but the professional musicians actually performed worse than before the stimulation. 
Now no theories have been absolutely confirmed but it’s possible that during excitatory tDCS the neurons being stimulated are more likely to fire and so for the unskilled learner they are more likely to find the correct sequence of neurons to perform a certain skill or task. However, with a skilled performer the correct sequence of neurons firing may already be well established and thus excitatory tDCS may spur an incorrect sequence to fire and thus skill is diminished. So if you’re worried about tDCS being used for performance enhancement in sports you can breathe a sigh of relief, and get back to watching the sports you love.
This creates an interesting question for tDCS Products like Halo Neuroscience’s headset the Halo SportHalo SH for athletes (www.haloneuro.com) Its clear that the creators have put a lot of time and effort into the product however, this is targeted towards the motor cortex. Their data seems to suggest minor increases in athletic performance but not a clear indication as to how they arrived at these numbers. Perhaps these athletes were training in new moves they did not have dialed in? Or new motions that they would not be considered an expert in? Both my co-founder and I are interested in seeing where this goes and only time will tell.