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Ethical and Regulatory Concerns About Direct-to-Consumer Brain Stimulation for Athletic Enhancement

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Transcranial direct current stimulation (tDCS) is currently under investigation as a promising technique for enhancement of athletic performance through modulating cortical excitability. Through consecutive randomization, 12 experienced bodybuilders were randomly assigned to two arms receiving either sham or real tDCS over the primary motor cortex (leg area) and left temporal cortex (T3) for 13 minutes in the first session. After 72 hours, both groups received the inverse stimulation. After the brain stimulation, cerebral hemodynamic response (using frontopolar hemoencephalography) was examined upon taking three computer-based cognitive tasks i.e. reasoning, memory and verbal ability using the Cambridge Brain Science-Cognitive Platform. Subsequently, the bodybuilders performed knee extension exercise while performance indicators including one-repetition maximum (1RM), muscular endurance (SEI), heart rate (ECG), motivation (VAS), surface electromyography over quadriceps femoris muscle (sEMG) and perceived exertion (RPE) were evaluated. The real tDCS vs. sham group showed decreased RPE and HR mean scores by 14.2% and 4.9%, respectively. Regarding muscular strength, endurance, and electrical activity, the 1RM, SEI, and sEMG factors improved by 4.4%, 16.9%, and % 5.8, respectively. Meanwhile, compared to sham, real tDCS did not affect the athletes’ motivation. Incidentally, it turned out that subjects who underwent T3 anodal stimulation outperformed in memory (p = 0.02) and verbal functions (0.02) as well as their corresponding frontopolar hemodynamic response [(memory HEG (p = 0.001) and verbal HEG (p = 0.003)]. Our findings suggest that simultaneous tDCS-induced excitation over the M1 leg area and left temporal area may potentially improve the overall athletic performance in experienced bodybuilders (Trial registration: IRCT20181104041543N1, Registered on 4 Nov. 2018, retrospectively registered).
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The present study investigated the effects of transcranial direct current stimulation (tDCS) using the Halo Sport device on repeated sprint cycling ability and on cognitive performance. In this triple-blind, randomized, sham-controlled study, nine physically active participants received either a placebo stimulation (Sham) or real stimulation (Halo) for 20 min. Participants then performed 5 × 6-s sprints interspersed with 24 s of active recovery on a cycle ergometer. Peak and mean power output were measured for each sprint. In addition, cognitive performance in terms of reaction time (RT) and accuracy (ACC) was assessed via Stroop test pre- and post-stimulation. There was a significant interaction for mean power output [F(4,32) = 2.98, P = 0.03]. A main treatment effect was observed in all of the repeated sprints apart from the initial one. Halo did not affect RT in either the congruent or incongruent condition but did increase ACC in the incongruent condition [F(1,8) = 10.56, P = 0.012]. These results suggest that tDCS with the Halo Sport system is able to enhance aspects of sprint cycling ability and cognitive performance.
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Objective To examine the effects of transcranial direct current stimulation (tDCS) on objective and subjective indexes of exercise performance. Design Systematic review and meta-analysis. Data sources A systematic literature search of electronic databases (PubMed, Web of Science, Scopus, Google Scholar) and reference lists of included articles up to June 2018. Eligibility criteria Published articles in journals or in repositories with raw data available, randomized sham-controlled trial comparing anodal stimulation with a sham condition providing data on objective (e.g. time to exhaustion or time-trial performance) or subjective (e.g. rate of perceived exertion) indexes of exercise performance. Results The initial search provided 420 articles of which 31 were assessed for eligibility. Finally, the analysis of effect sizes comprised 24 studies with 386 participants. The analysis indicated that anodal tDCS had a small but positive effect on performance g = 0.34, 95% CI [0.12, 0.52], z = 3.24, p = .0012. Effects were not significantly moderated by type of outcome, electrode placement, muscles involved, number of sessions, or intensity and duration of the stimulation. Importantly, the funnel plot showed that, overall, effect sizes tended to be larger in studies with lower sample size and high standard error. Summary The results suggest that tDCS may have a positive impact on exercise performance. However, the effect is probably small and most likely biased by low quality studies and the selective publication of significant results. Therefore, the current evidence does not provide strong support to the conclusion that tDCS is an effective means to improve exercise performance.
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Brain stimulation and neural entrainment relying on noninvasive techniques, applied to sports, might enhance brain activity in healthy athletes to improve their physical performance. In the past, several studies have employed stimulation procedures, either during athletic training or during separate sessions, to enhance physical and mental performance. Here, we review the available physiological and behavioral studies to clarify if and under which conditions noninvasive brain stimulation and neural entrainment might enhance athletic performance. Even though many studies suffer from small sample size, the results, compared to traditional training procedures, suggest advantages with regard to motor learning, motion perception, muscular strength, or decrements in muscle fatigue. Further, these techniques seem to be useful in fine-tuning crucial aspects of competitive sports such as speeding up the learning rate of specific motor skills. Although more research is needed to fully understand the effects of noninvasive brain stimulation and neural entrainment on athletic performance, we conclude that these emerging techniques are promising tools to enhance physical and mental performances in sports.
Article
The direct-to-consumer (DTC) neurotechnology market, which includes some brain-computer interfaces, neurostimulation devices, virtual reality systems, wearables, and smartphone apps is rapidly growing. Given this technology’s intimate relationship with the brain, a number of ethical dimensions must be addressed so that the technology can achieve the goal of contributing to human flourishing. This paper identifies safety, transparency, privacy, epistemic appropriateness, existential authenticity, just distribution, and oversight as such dimensions. After an initial exploration of the relevant ethical foundations for DTC neurotechnologies, this paper lays out each dimension and uses examples to justify its inclusion.
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Background: Transcranial direct current stimulation (tDCS) has been used to improve exercise performance, though the protocols used, and results found are mixed. Objective: We aimed to analyze the effect of tDCS on improving exercise performance. Methods: A systematic search was performed on the following databases, until December 2017: PubMed/MEDLINE, Embase, Web of Science, SCOPUS, and SportDiscus. Full-text articles that used tDCS for exercise performance improvement in adults were included. We compared the effect of anodal (anode near nominal target) and cathodal (cathode near nominal target) tDCS to a sham/control condition on the outcome measure (performance in isometric, isokinetic or dynamic strength exercise and whole-body exercise). Results: 22 studies (393 participants) were included in the qualitative synthesis and 11 studies (236 participants) in the meta-analysis. The primary motor cortex (M1) was the main nominal tDCS target (n = 16; 72.5%). A significant effect favoring anodal tDCS (a-tDCS) applied before exercise over M1 was found on cycling time to exhaustion (mean difference = 93.41 s; 95%CI = 27.39 s to 159.43 s) but this result was strongly influenced by one study (weight = 84%), no effect was found for cathodal tDCS (c-tDCS). No significant effect was found for a-tDCS applied on M1 before or during exercise on isometric muscle strength of the upper or lower limbs. Studies regarding a-tDCS over M1 on isokinetic muscle strength presented mixed results. Individual results of studies using a-tDCS applied over the prefrontal and motor cortices either before or during dynamic muscle strength testing showed positive results, but performing meta-analysis was not possible. Conclusion: For the protocols tested, a-tDCS but not c-tDCS vs. sham over M1 improved exercise performance in cycling only. However, this result was driven by a single study, which when removed was no longer significant. Further well-controlled studies with larger sample sizes and broader exploration of the tDCS montages and doses are warranted.
Chapter
Non-invasive brain stimulation techniques have been used for decades to study brain function and for the treatment of various neurological disease. These techniques involve the passage of electrical current or magnetic field in a controlled manner to a targeted brain area. Recently, experimental studies explored the application of transcranial direct current stimulation (tDCS) for the improvement of physical performance in healthy individuals. In this chapter we reviewed and analyzed the current scientific literature, highlighted methodological limitations and also suggested possible neurophysiological mechanisms. The chapter also provides some technical and theoretical research-based principles for future research, to promote a better understanding of potential and caveats of this emerging field. Finally, ethical and regulatory issues related to performance enhancement via non-invasive brain stimulation are also discussed.
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Transcranial electrical stimulation (tES) is a neuromodulatory technique in which low voltage constant or alternating currents are applied to the human brain via scalp electrodes. The basic idea of tES is that the application of weak currents can interact with neural processing, modify plasticity and entrain brain networks, and that this in turn can modify behaviour. The technique is now widely employed in basic and translational research, and increasingly is also used privately in sport, the military and recreation. The proposed capacity to augment recovery of brain function, by promoting learning and facilitating plasticity, has motivated a burgeoning number of clinical trials in a wide range of disorders of the nervous system.
Article
We present device standards for low-power non-invasive electrical brain stimulation devices classified as limited output transcranial electrical stimulation (tES). Emerging applications of limited output tES to modulate brain function span techniques to stimulate brain or nerve structures, including transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), and transcranial pulsed current stimulation (tPCS), have engendered discussion on how access to technology should be regulated. In regards to legal regulations and manufacturing standards for comparable technologies, a comprehensive framework already exists, including quality systems (QS), risk management, and (inter)national electrotechnical standards (IEC). In Part 1, relevant statutes are described for medical and wellness application. While agencies overseeing medical devices have broad jurisdiction, enforcement typically focuses on those devices with medical claims or posing significant risk. Consumer protections regarding responsible marketing and manufacture apply regardless. In Part 2 of this paper, we classify the electrical output performance of devices cleared by the United States Food and Drug Administration (FDA) including over-the-counter (OTC) and prescription electrostimulation devices, devices available for therapeutic or cosmetic purposes, and devices indicated for stimulation of the body or head. Examples include iontophoresis devices, powered muscle stimulators (PMS), cranial electrotherapy stimulation (CES), and transcutaneous electrical nerve stimulation (TENS) devices. Spanning over 13 FDA product codes, more than 1200 electrical stimulators have been cleared for marketing since 1977. The output characteristics of conventional tDCS, tACS, and tPCS techniques are well below those of most FDA cleared devices, including devices that are available OTC and those intended for stimulation on the head. This engineering analysis demonstrates that with regard to output performance and standing regulation, the availability of tDCS, tACS, or tPCS to the public would not introduce risk, provided such devices are responsibly manufactured and legally marketed. In Part 3, we develop voluntary manufacturer guidance for limited output tES that is aligned with current regulatory standards. Based on established medical engineering and scientific principles, we outline a robust and transparent technical framework for ensuring limited output tES devices are designed to minimize risks, while also supporting access and innovation. Alongside applicable medical and government activities, this voluntary industry standard (LOTES-2017) further serves an important role in supporting informed decisions by the public.
Article
Number of substances and strategies are available to increase performance in sport (Catlin and Murray, 1996). Since 2004, the World Anti-Doping Agency (WADA) posts an updated list of substances and methods prohibited to athletes. Drugs (e.g., steroids, stimulants) are a major part of this list; however, technologies and methods (e.g., gene doping) are increasingly being identified and added (WADA, 2017). Among technologies and methods that might exert a potential effect on athletic performance, brain stimulation has recently been subjected to extensive discussion. Neuro-enhancement for doping purposes has been termed “neurodoping” in the literature (Davis, 2013); however, this concept needs further documentation before the term “neurodoping” can be used properly. Two major non-invasive techniques of brain stimulations are transcranial magnetic stimulation (TMS) (Hallett, 2007; Rossi et al., 2009), and transcranial direct current stimulation (tDCS) (Stagg and Nitsche, 2011). In TMS, an electric coil held over the head applies magnetic pulses to create currents in the brain. In tDCS, a low, continuous electrical current is delivered to the brain by using surface electrodes attached on the scalp. TMS and tDCS have been used in both research and clinic (Shin and Pelled, 2017) for example to examine alterations in cognitive function or motor skills or to assist in recovering motor function after a stroke (Gomez Palacio Schjetnan et al., 2013) or reducing fatigue in patients with multiple sclerosis (Saiote et al., 2014). In an opinion paper, it was proposed that use of emerging brain stimulation techniques might also enhance physical and mental performance in sports (Davis, 2013). The assumption was based on several reports. For example some studies have shown that TMS could shorten reaction times to visual, auditory and touch stimuli, reduce tremor, and enhance the acquisition of complex motor skills. Based on the current evidence, a recent review (Colzato et al., 2017) has summarized that overall brain stimulation by some techniques including TMS and tDCS seem to speed up motor learning, and motor skills in sport activities. Considering that performance enhancement can be seen (Colzato et al., 2017), one would ask how and by which mechanism. Davis proposed that there would be two ways that brain stimulation could possibly improve sport performance (Davis, 2013). One way is to benefit from brain stimulation before performance to, for instance, reduce stress level or muscle tension or to enhance focus for a quicker action. The other way would be potential use during training for athletic performance that can eventually help athletes to learn motor skills better. Presented research results are mainly based on the experimental set up; therefore, it is important to identify whether physical and mental performance gains under experimental conditions would also be meaningful in a real world competition. To study actual gain by brain stimulation, future investigations must properly be designed, include placebo and control arms, remain blinded until after data analysis, and include objective assessments in addition to subjective outcomes. Time-course of beneficial effect in certain sport competition is not clear. It has been shown that repetitive applications of tDCS can increase the effects of stimulation (Nitsche and Paulus, 2011); but, it is not clear if this is the case for athletic performance. There is no evidence on side effects especially for long term use of these techniques. Overall, these techniques are considered non-invasive and safe (Rossi et al., 2009). Under medical application, it has been notified that some individuals are highly responders while others do not respond well. This might be the case for athletes. Additive or synergistic effects of these techniques together with other techniques or methods of performance enhancement have not yet been investigated either. Therefore, further studies are required to address these uncertainties or providing an optical protocol. Discussing neuro-enhancement with sport bodies, athletes, and authorities seems necessary to facilitate providing a technical, ethical, or regulatory framework for further investigation (Park K, 2017). In contrast to many other substances or strategies listed in prohibited performance-enhancing drugs or strategies, neuro-enhancement cannot be detected with a simple blood test. In addition, since these techniques can be used differently for different types of sport activities, it is not easy to determine whether it must be prohibited or be given legitimacy as an aid to training and development of athletes. In short, although brain stimulation is a valuable scientific tool and a beneficial medical procedure, it does not look wise to let it be used limitlessly and for non-medical purposes at least for the time being that several points are unanswered about efficacy and safety.