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Acute effect of high-definition and conventional tDCS on exercise performance and psychophysiological responses in endurance athletes: a randomized controlled trial.
da Silva Machado, DG, Bikson, M, Datta, A, Caparelli-Dáquer, E, Unal, G, Baptista, AF, Cyrino, ES, Li, LM, Morya, E, Moreira, A, et al
Scientific reports. 2021;11(1):13911
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Exercise-induced fatigue can be associated with a limited descending command from the central nervous system to the muscle which may affect muscle contraction and its ability to generate force. Transcranial direct current stimulation (tDCS) is the application of weak electrical current to stimulate different areas of the brain to influence exercise performance and perception. High-definition transcranial direct current stimulation (HD-tDCS) is a modification of conventional tDCS to increase the focality, precision, long-lasting effects and greater neuronal excitability change. This single-centre, randomised, crossover, single-blinded, sham-controlled trial compared the effects of HD-tDCS and conventional tDCS on exercise performance and psychophysiological responses in healthy young male endurance athletes. The study found no effect of HD-tDCS or conventional tDCS on exercise performance and psychophysiological responses to exhaustive exercise. Further robust studies are required to evaluate the effects of both forms of tDCS in athletes compared to non-athletes and its effects when tDCS is applied to other areas of the central nervous system. Healthcare professionals can use the results of this study to understand that there is no evidence currently to support the utilisation of tDCS in improving exercise performance in athletes.
Abstract
Transcranial direct current stimulation (tDCS) has been used aiming to boost exercise performance and inconsistent findings have been reported. One possible explanation is related to the limitations of the so-called "conventional" tDCS, which uses large rectangular electrodes, resulting in a diffuse electric field. A new tDCS technique called high-definition tDCS (HD-tDCS) has been recently developed. HD-tDCS uses small ring electrodes and produces improved focality and greater magnitude of its aftereffects. This study tested whether HD-tDCS would improve exercise performance to a greater extent than conventional tDCS. Twelve endurance athletes (29.4 ± 7.3 years; 60.15 ± 5.09 ml kg-1 min-1) were enrolled in this single-center, randomized, crossover, and sham-controlled trial. To test reliability, participants performed two time to exhaustion (TTE) tests (control conditions) on a cycle simulator with 80% of peak power until volitional exhaustion. Next, they randomly received HD-tDCS (2.4 mA), conventional (2.0 mA), or active sham tDCS (2.0 mA) over the motor cortex for 20-min before performing the TTE test. TTE, heart rate (HR), associative thoughts, peripheral (lower limbs), and whole-body ratings of perceived exertion (RPE) were recorded every minute. Outcome measures were reliable. There was no difference in TTE between HD-tDCS (853.1 ± 288.6 s), simulated conventional (827.8 ± 278.7 s), sham (794.3 ± 271.2 s), or control conditions (TTE1 = 751.1 ± 261.6 s or TTE2 = 770.8 ± 250.6 s) [F(1.95; 21.4) = 1.537; P = 0.24; η2p = 0.123]. There was no effect on peripheral or whole-body RPE and associative thoughts (P > 0.05). No serious adverse effect was reported. A single session of neither HD-tDCS nor conventional tDCS changed exercise performance and psychophysiological responses in athletes, suggesting that a ceiling effect may exist.
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Long-chain n-3 PUFAs reduce adipose tissue and systemic inflammation in severely obese nondiabetic patients: a randomized controlled trial.
Itariu, BK, Zeyda, M, Hochbrugger, EE, Neuhofer, A, Prager, G, Schindler, K, Bohdjalian, A, Mascher, D, Vangala, S, Schranz, M, et al
The American journal of clinical nutrition. 2012;96(5):1137-49
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Adipose tissue inflammation is the basis of obesity-related systemic inflammation, which predisposes patients to the development of metabolic and cardiovascular disease. Previous studies show that long-chain omega-3 polyunsaturated fatty acids (n-3 PUFAs) reduce cardiovascular events and exert anti-inflammatory effects but their effects on human adipose tissue inflammation have so far been unknown. This randomized open-label controlled clinical trial evaluated the effect of an 8-week treatment with n-3 PUFAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on adipose tissue and systemic inflammation and on metabolic control. Fifty-five severely obese non-diabetic patients, scheduled for bariatric surgery, were allocated to receive either n-3 PUFAs (n=27) or an equivalent amount of butterfat as control (n=28). Systemic inflammatory markers and metabolic variables were measured at baseline and at the end of the intervention before the participants underwent bariatric surgery. Adipose tissue samples were collected during surgery for the assessment of inflammatory gene expression and lipid mediator production. Treatment with n-3 PUFAs for 8 weeks favourably affected adipose tissue and systemic inflammation. In adipose tissue, the expression of most inflammatory genes was reduced and the concentrations of lipid mediators, responsible for the resolution of inflammation (resolving lipid mediators), were increased. Systemically, the results showed a shift to a more anti-inflammatory plasma fatty acid profile and a decrease in circulating triglyceride levels. The authors concluded that the observed beneficial effects of n-3 PUFAs may be useful in the long-term treatment of obesity.
Abstract
BACKGROUND Chronic adipose tissue inflammation is a hallmark of obesity, triggering the development of associated pathologies, particularly type 2 diabetes. Long-chain n-3 PUFAs reduce cardiovascular events and exert well-established antiinflammatory effects, but their effects on human adipose tissue inflammation are unknown. OBJECTIVE We investigated whether n-3 PUFAs reduce adipose tissue inflammation in severely obese nondiabetic patients. DESIGN We treated 55 severely obese nondiabetic patients, scheduled to undergo elective bariatric surgery, with 3.36 g long-chain n-3 PUFAs/d (EPA, DHA) or an equivalent amount of butterfat as control, for 8 wk, in a randomized open-label controlled clinical trial. The primary efficacy measure was inflammatory gene expression in visceral and subcutaneous adipose tissue samples (subcutaneous adipose tissue and visceral adipose tissue), collected during surgery after the intervention. Secondary efficacy variables were adipose tissue production of antiinflammatory n-3 PUFA-derived eicosanoids, plasma concentrations of inflammatory markers, metabolic control, and the effect of the Pro12Ala PPARG polymorphism on the treatment response. RESULTS Treatment with n-3 PUFAs, which was well tolerated, decreased the gene expression of most analyzed inflammatory genes in subcutaneous adipose tissue (P < 0.05) and increased production of antiinflammatory eicosanoids in visceral adipose tissue and subcutaneous adipose tissue (P < 0.05). In comparison with control subjects who received butterfat, circulating interleukin-6 and triglyceride concentrations decreased significantly in the n-3 PUFA group (P = 0.04 and P = 0.03, respectively). The Pro12Ala polymorphism affected the serum cholesterol response to n-3 PUFA treatment. CONCLUSIONS Treatment with long-chain n-3 PUFAs favorably modulated adipose tissue and systemic inflammation in severely obese nondiabetic patients and improved lipid metabolism. These effects may be beneficial in the long-term treatment of obesity. This trial was registered at clinicaltrials.gov as NCT00760760.