For access to all of our training, gear, and race coverage, plus exclusive training plans, FinisherPix photos, event discounts, and GPS apps, sign up for Outside+.
Sending electrical currents through the brain may make us stronger, faster, more resilient athletes. But is the tech ready for us yet?
Roman doctors once sought to cure headaches by placing a live electric ray on the sufferer’s forehead.
Fast forward a couple millennia, and transcranial direct-current stimulation (tDCS) of targeted areas of the brain is being used, with more precision, for a broad range of medical purposes—pain control, depression, schizophrenia, epilepsy, Parkinson’s. It’s also being used to enhance learning, memory, and attention span in healthy people.
In 2013, some of the same team who had developed an FDA-approved neurostimulator to control epilepsy applied that science to improving athletic performance, forming a company called Halo Neuroscience. The idea behind the tech is that a mild electric field applied to the motor cortex excites the millions of neurons responsible for muscle movement.
When you train with neurons in this excited state—”hyperplastic” is the term Halo uses—a few things happen: Neurons fire more readily; more of them fire, so more muscle fibers are recruited; they fire in the right order, to produce strong, smooth, efficient movements; and neural pathways responsible for trained movements are strengthened, i.e. adaptation and muscle memory is improved. But excited neurons that don’t get any action (training) produce nothing: Halo only works if you train while the noggin is hot. Then, the theory goes that you get more bang for the same training buck.
Fans of the 1975 film One Flew Over The Cuckoo’s Nest can rest easy. Though not FDA-approved, Halo uses about a thousand times less amperage, one to two milliamps, than Nurse Ratched favored, and no serious adverse effects have been reported in 33,200 documented sessions. Current moving through the wet spongy headset nibs to the scalp can be dialed up or down, but the difference between level 1 and 10 is a matter of comfort rather than safety.
But Does It Work?
Despite thousands of scientific papers on the subject, we may not have progressed much beyond the Romans in terms of unintended results. In July 2016, a group of scientists and clinicians published an editorial in the Annals of Neurology warning of undesired effects. They pointed out that zapping the brain may help the user to learn a new skill but diminish the ability to process an already learned skill. Variables such as where the electrodes are placed on the scalp, how much current is used and for how long, the age and skull thickness of the user, and even daily variations in the same user can change tDCS’s effect in unknown and possibly undesirable ways.
Part of the issue stems from the fact that, to send a current through anything, you need both positive and negative electrodes. That makes it tough to target the exact neurons you want to excite, because those under the negative electrode will get riled up, but those under the positive one will simmer down. It’s possible that placing the positive electrode somewhere else on the body can diminish any negative effects, but research is far from conclusive at this point.
While Halo’s consumer device—which looks like a pair of headphones—is endorsed by pro triathletes including Sarah Piampiano and Tim O’Donnell and costs $750, a DIY tDCS device can be built for less than $20, as long as you’re willing to be the test subject.
Given what researchers currently know about tDCS, it’s fair to conclude that Halo might’ve been a bit quick to market with an entirely noggin-based consumer device. That said, whether it’s because of the Halo device or a placebo effect, Piampiano has nothing but good things to say about her sessions with the headset, which she uses for about 20 minutes, three times a week, before key training sessions.
“I’m really sold on it,” she says. “Earlier this year, I did 70.3 Santa Rosa and had the fastest run split of the day—1:18. I’ve never run under 1:20 before. I’ll give credit to the training my coach, Matt Dixon, is providing, but I’ve been able to consistently hit the very top limits of those workouts.”