Halo 2 - Does tDCS create a state of 'hyperlearning'?

The snapshot

Report of the Evidence, An Independent Academic Viewpoint

By Professor Steve Haake & Dr David Broom

Halo 2

      The full picture

      HALO SPORT 2 is a device that you wear like a set of headphones. It applies a small electric current to the brain in a process known as transcranial direct current stimulation (tDCS). The current acts on the part of the brain which controls movement i.e. the motor cortex. This activates neurons to increase the brain’s electrical potential. Manufactured by Halo Neuroscience (San Francisco, CA, United States; product website) it is claimed that the HALO SPORT 2 strengthens motor pathways so that by wearing the HALO SPORT 2 one speeds up the learning of gross and fine motor skills and ultimately movement. The following is a review of some of the science that supports the claims.

      The motor cortex is a complex network of interconnected localized groups of neurons with similar inputs and outputs, whose purpose is to control movements(www.frontiersin.org/articles/10.3389). The role of the motor cortex is to generate neural impulses that control the execution of movement and it is claimed that HALO SPORT 2 produces changes in motor cortex excitability. 

      Playing the piano, doing press ups and running are examples of different motor skills, but the brain learns each of these movements in the same way via the motor cortex. While the pathways in the brain that produce each movement differ, they can be improved through neuroplasticity. The brain sends signals to the correct muscles in a specific order to create a movement; with HALO SPORT 2 the number of learning repetitions may be reduced because the neurons are primed through the application of tDCS. 

      One possible mechanism for this improvement is that the electrical stimulation from the HALO SPORT 2 increases intracortical facilitation and motor cortex excitability, allowing motor-cortex neurons to build neural connections more easily, enhancing motor drive to the muscles. The use of tDCS has been reported as being safe by Bikson et al (2016) with no serious adverse events reported.  The volume of research to support the efficacy of tDCS is extensive, with claims of over 4,000 studies some specifically testing the HALO SPORT 2. The following are some examples: 

      Cycling mean power output - Power and strength

      Huang et al (2019) used the HALO SPORT 2 in a triple-blind, randomized, sham-controlled study. Nine physically active participants received either a placebo stimulation (sham) or real stimulation (HALO SPORT 2) for 20 minutes. Participants then performed 5 × 6 second sprints interspersed with 24 seconds of active recovery using a cycle ergometer. HALO SPORT 2 led to an improvement in mean power output but not peak power output. In addition, cognitive performance i.e. reaction time and accuracy was assessed via the well-known Stroop test pre- and post-stimulation. The Stroop test is a classical assessment that measures multiple aspects of cognitive function, including information processing speed, sustaining attention, interference, and inhibition. HALO SPORT 2 did not affect reaction time but did increase accuracy. These results suggest that tDCS with HALO SPORT 2 is able to enhance aspects of sprint cycling ability and cognitive performance.

      Run time to exhaustion - Endurance

      Using a randomized, single-blinded, and counterbalanced design Park et al (2019) recruited 10 trained men who received either 20 minutes of 1.98 mA anodal tDCS applied over the primary motor cortex or sham-operated control on separate days. The participants completed a constant-load test involving running at a speed equivalent to 80% of their own maximum oxygen consumption (VO2max).Throughout the running, rating of perceived exertion (RPE), heart rate (HR), oxygen consumption (VO2), pulmonary ventilation (VE), respiratory exchange ratio (RER), and ventilatory threshold (VT) were continuously monitored. Time to exhaustion was recorded at the end of the test which was significantly longer in the tDCS than in the sham condition (21.18 ± 7.13 minutes vs 18.44 ± 6.32 minutes). No significant differences were found in RPE, HR, VO2, VE, RER, and VT between the two stimulation conditions at any time point.  Thus, time to exhaustion was increased without an increased perception of exertion or changes in respiratory physiology. 

      Hand configuration task - Fine Motor Skills

      Waters-Metenier et al. (2014) determined the effects of tDCS on the learning of motor synergies using a novel hand configuration task that required the production of difficult muscular activation patterns. tDCS was applied to the motor cortex of 52 (27 Male; 25 Female) healthy, right-handed participants during 4 days of repetitive left-hand configuration training in a double-blind design. tDCS significantly improved synergy learning, leading subsequently to faster and more synchronized execution. This effect persisted for at least 4 weeks after training.

      Using the HALO SPORT2

      A phone is paired with the HALO SPORT 2 using the app. After selecting a specific activity such as 'lifting - legs, core and arms' the contact points of the primer band are wetted and it is inserted into the headset. The HALO SPORT 2 is worn like a normal pair of headphones. A HALO SPORT 2 training session has two phases:

      1) A neuropriming phase for 20 minutes which consists of stretching, warming up and visualization. Weak direct currents below 2–3 mA are delivered for a period of minutes over the scalp through surface electrodes, termed primers. 

      2) A training phase during which the headset can be removed (or kept on to listen to music). The tDCS benefits begin after about 5 minutes and continue for about an hour after the initial neuropriming phase. 


      For those wanting to improve their motor skills or cognitive abilities, there is evidence that HALO SPORT 2 can improve performance.  This may be achieved through improved neuroplasticity but may also build in the placebo effect, where therapeutic or performance outcomes occur even if the treatment is inert.  


      Bikson, M. et al. (2016). Safety of Transcranial Direct Current Stimulation: Evidence Based Update 2016. Brain Stimulation, 9(5), 641-661.

      Huang, L. et al (2019). Transcranial Direct Current Stimulation With Halo Sport Enhances Repeated Sprint Cycling and Cognitive Performance. Frontiers in Physiology, 10(118).

      Park, S.B. et al (2019). Transcranial Direct Current Stimulation of motor cortex enhances running performance. PLoS One, 14(2). 

      Schieber, M. H. (2001). Constraints on somatotopic organization in the primary motor cortex. Journal of Neurophysiology, 86, 2125–2143.

      Waters-Metenier S. et al (2014). Bihemispheric transcranial direct current stimulation enhances effector-independent representations of motor synergy and sequence learning. Journal of Neuroscience, 34(3).

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        Sheffield Hallam University

        Review completed and approved for use by Sheffield Hallam University


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