While it is just a couple of milliamps of positive electric current (about what a 9-volt battery produces), as an engineer who has had to worry about maximum electrical current tolerances for creating safe medical devices, I admit that the thought of zapping my brain using a headset initially made me feel uneasy. However, after speaking to Emily Hu, an elite powerlifter (not coincidentally, a triple world record holder in bench press in two weight classes), my skepticism gave way to my greater curiosity and I decided to zap my own brain.
Created by Halo Neuroscience, a Silicon Valley firm founded by Dr. Daniel Chao and Dr. Brett Wingeier, the Halo Sport uses a process called transcranial direct current stimulation (tDCS) to stimulate the brain. It sends a low level electric current of around 1.4 to 2.2 milliamps to a targeted region of the brain to excite the neurons, effectively “priming” them to be more likely to fire and create new neural pathways. This means that the brain temporarily becomes better at hard-coding what you are doing.
In effect, this is what the Halo Sport headset created by Halo Neuroscience is supposed to do. This headset stimulates the motor cortex, the part of the brain that controls movement, and primes the brain to get better faster at exercises in a workout, playing the piano, or any other activity that may require trained physical movements.
The brain’s role in exercise is more than just the mechanics involved in precise movement-relatedskills: it is also involved the mastery of muscle groups and muscle memory. 
Therefore, it is not about how big your muscles are, but how well you can use those muscles. Neuropriming therefore plays a role in accelerating gains in strength, endurance, and skill. In other terms, the technology temporarily increases the brain’s neuroplastic state, or state of “hyperplasticity.”
Halo Neuroscience’s Headset Zaps Your Brain To Train It [Medgadget]