In the ultracompetitive world of professional sports, victory is measured in fractions of time and distance. The difference in performance between two elite athletes amounts to less than one percent. Consequently, professional athletes take great interest in ergogenic aids, which refer to any technique or substance used to enhance performance. Common legal ergogenic aids include multivitamin supplements and hypoxic training. Recently, the ability of brain stimulation to enhance sports performance has become an expanding focus of academic study.

In an October 2017 article titled “Bilateral extracephalic transcranial direct current stimulation improves endurance performance in healthy individuals,” Angius and co-authors used transcranial direct current stimulation (tDCS), a form of brain stimulation, to improve endurance in 12 healthy, active adults during 10-minute cycling sessions.

terriana/123RF
Source: terriana/123RF

tDCS explained

With tDCS, a weak electrical current is delivered to the brain via two scalp electrodes. The electrical current is generated by portable stimulators, which are battery-powered. Electrical currents generated by tDCS have a modulatory effect on cortical excitability. Anodal stimulation increases neural firing in the prefrontal cortex (anterior frontal lobe); whereas, cathodal stimulation decreases neural firing. Of note, tDCS can cause mild adverse effects, such as itching, mild tingling, burning, or fatigue.

Brain stimulation with tDCS has been used to treat various conditions including chronic pain and depression.

Study Design

Angius and colleagues recruited a total of 12 participants—8 men and 4 women—aged between 18 and 44. Although not elite athletes per se, the participants were “recreationally active” and engaged in at least 3 hours of aerobic activity per week.

According to the researchers, here is how the study was designed:

During the three experimental visits, participants were randomly assigned in a double-blind, randomized, counterbalanced order to a sham (SHAM), anodal (ANODAL) and cathodal (CATHODAL) stimulation conditions. Participants were given instructions to avoid caffeine, alcohol, stimulants or depressants, and strenuous exercise for 48 h prior to each visit.

Both before and after tDCS, the researchers assessed neuromuscular performance by measuring time to task failure among participants engaged in cycling sessions. They found that placing the anodes over both motor cortices augments endurance performance. In other words, cyclists who received anodal stimulation biked longer before quitting than did those under the cathodal and sham conditions.    

In addition to observing changes in corticospinal excitability in those receiving anodal stimulation, the researchers found that their ratings of perceived exertion were also lower. The researchers suggest “the increase in endurance performance might be the result of higher excitability of the motor cortex leading to a reduction in perception of effort.”

Certain stakeholders have high hopes for tDCS that extend past sports performance and include training adaptations and neuroplasticity. To date, only four other studies have examined the effects of tDCS on measures of endurance. Nevertheless, the results of the current study are encouraging and could help bolster the spread of tDCS among professional athletes.

The Halo Sport, a wearable neurostimulation device, which looks like a pair of headphones and leverages tDCS technology, is becoming popular among NFL athletes, MLB athletes, Olympic athletes, and more. The device promises improvements in strength, skill, speed, and endurance.

References

Angius L, et al. Bilateral extracephalic transcranial direct current stimulation improves endurance performance in healthy individuals. Brain Stimulation. 2017;1-10.

Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet]. York (UK): Centre for Reviews and Dissemination (UK); 1995-. Transcranial magnetic stimulation and transcranial direct current stimulation: treatments for cognitive and neuropsychiatric symptoms in the neurodegenerative dementias. 2014.

Thein LA, Thein JM, Landry GL. Ergogenic Aids. Physical Therapy. 1995;75(5):426-39.

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