O Perigo Da ContaminaÇÃo De Suplementos Alimentares Com SubstÂncias IlÍcitas Para Os Praticantes De ExercÍcio FÍsico E Esporte

O objetivo dessa revisão foi explicitar o perigo da presença de substâncias ilícitas em suplementos alimentares para os praticantes de exercício físico recreativo e atletas de elite. Há muitos anos, estudos vêm sendo feitos para melhorar o desempenho de atletas em competições e, com isso, o uso de suplementos vem aumentando gradualmente. Mas o problema é que se sabe que os suplementos alimentares nem sempre estão livres de substâncias não desejadas, muitas vezes estando contaminados com substancias proibidas pelas organizações esportivas. Vários estudos foram realizados para verificar a presença de tais contaminantes e os resultados foram alarmantes, aumentando a preocupação de atletas, treinadores e equipes quanto ao uso de suplementos alimentares. Alguns atletas que realizaram o teste anti-doping apresentaram exames positivos para substancias ilícitas e afirmaram não ter conhecimento de estarem usando as mesmas. Isso é chamado de doping não intencional, porém pode trazer grande prejuízo para o atleta. Infelizmente, as leis e controle sobre esse problema não são rigorosas o suficiente para acabar com a situação. Por isso, organizações e comitês esportivos devem informar os atletas sobre os suplementos mais seguros a serem utilizados e seria importante a criação de novas leis para o controle na produção.121161-180Educação FísicaNutriçã

Electronic music effects on neuromuscular and cardiovascular systems and psychophysiological parameters during exhaustive incremental test

The aim of this study was to analyze the music effects on physiological and psychophysiological responses, as well as on the maximum power output attained during an incremental test. A sample of 10 healthy individuals (20.8 ± 1.4 years, 77.0 ± 12.0 kg, 179.2 ± 6.3 cm) participated in this study. It was recorded the electromyographic activity (muscles Rectus Femoris − RF and Vastus Lateralis − VL), heart rate (HR), rating of perceived exertion (RPE), ratings of perceived time (RPT) and the maximum power output attained (PMax) during music (WM) and without music (WTM) conditions. The individuals completed four maximal incremental tests (MIT) ramp-like on a cycle simulator with initial load of 100 W and increments of 10 W·min-1. The mean values of PMax between conditions WTM (260.5 ± 27.7 W) and WM (263.2 ± 17.2 W) were not statistically different. The comparison between the rates of increase of the values expressed in root-mean-square (RMS) and median frequency (MF) for both muscles (RF and VL) also showed no statistical difference, as well as HR, RPE and RPT. It is concluded that the use of the electronic music during an incremental test to exhaustion showed no effect on the analyzed variables for the investigated group

Brain stimulation for health and exercise performance improvement

The technological advances of the last decades have provided the effective use of noninvasive techniques in neuromodulation with concomitant health benefits. Currently, the main neuromodulation techniques are transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS). Through literature review, this study addresses the a) history of brain stimulation and the b) mechanisms of action studied by motor neurophysiology, pharmacology, neuroimaging, and experimental animals. Moreover, it is presented the c) perspectives for applications of brain stimulation for promoting health and improving physical performance, including cardiac autonomic control and post-exercise hypotension, control and modulation of appetite, fatigue and physical performance. Finally, we describe d) the security aspects related to the use of tDCS. Thus, tDCS seems to be an effective and safe technique to modulate brain function and suggests some application associated to food intake, cardiovascular health and physical performance.O avanço tecnológico das últimas décadas tem proporcionado o uso eficaz de técnicas não-invasivas na neuromodulação cerebral. Atualmente, as principais técnicas de neuromodulação são a estimulação magnética transcraniana (EMT) e a estimulação transcraniana por corrente contínua (ETCC). Por meio de revisão da literatura, o presente estudo aborda: a) história da estimulação cerebral; b) mecanismos de ação estudados através da neurofisiologia motora, farmacologia, neuroimagem e animais experimentais; c) perspectivas de aplicações da estimulação cerebral para promoção da saúde e melhoria do desempenho físico, incluindo o controle autonômico cardíaco e hipotensão pós-exercício, o controle de apetite e a modulação da fadiga e desempenho físico; e d) aspectos de segurança referentes ao uso da ETCC. Dessa forma, a ETCC parece ser uma técnica efetiva e segura para modular a função cerebral e podemos vislumbrar algumas perspectivas de aplicação no âmbito da ingestão alimentar, saúde cardiovascular e desempenho físico

Fat mass predicts food-specific inhibitory control in children

Impaired inhibitory control has been associated with obesity, high blood pressure and lack of physical fitness. These impairments are thought to be related to decreased cognitive control over excessive food consumption and may start in childhood. However, previous studies in children have examined inhibitory control deficits using general (non-food-specific) tasks and relied on body mass index, which does not distinguish the amount of fat mass. As fat mass, hypertension and physical fitness have been shown to play a role in cognition, the aim of this study was to investigate the relationship between these variables and food specific inhibitory control in children. Subjects/methods: Children's (n = 48; Age 10.7 +/- 0.6 years) general characteristics, fat mass, cardiorespiratory fitness, blood pressure and performance on a food-specific inhibitory control task (Go/No-go) were measured across two sessions. Results: Fat mass and sex were associated with inhibitory control performance, while no associations were found for cardiorespiratory fitness, blood pressure and other potential confounding variables (i.e. age, pubertal timing, body mass index, waist-to-hip ratio, scholar test performance and heart rate). Linear regression analyses showed that only fat mass predicted poorer food-specific inhibitory control (beta = 0.36; Delta R-2 = 0.04; p < .05) and sex predicted inhibitory control for toys (control condition) (beta = 0.42; Delta R-2 = 0.11; p < .01). Neither blood pressure nor cardiorespiratory fitness predicted food specific inhibitory control. Conclusion: These findings suggest that fat mass is an independent predictor of inhibitory control for food in children204155161COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESsem informaçã

Transcranial direct current stimulation influences the cardiac autonomic nervous control

AbstractTo investigate whether the manipulation of brain excitability by transcranial direct current stimulation (tDCS) modulates the heart rate variability (HRV), the effect of tDCS applied at rest on the left temporal lobe in athletes (AG) and non-athletes (NAG) was evaluated. The HRV parameters (natural logarithms of LF, HF, and LF/HF) was assessed in 20 healthy men before, and immediately after tDCS and sham stimulation. After anodal tDCS in AG the parasympathetic activity (HFlog) increased (P<0.01) and the sympathetic activity (LFlog) and sympatho-vagal balance (LF/HFlog) decreased (P<0.01), whereas no significant effects were detected in NAG (P>0.05). No significant changes in HRV indexes were provoked by sham stimulation in both AG and NAG (P>0.05). In conclusion, tDCS applied on the left temporal lobe significantly increased the overall HRV in AG, enhancing the parasympathetic and decreasing the sympathetic modulation of heart rate. Consequently the sympatho-vagal balance decreased at rest in AG but not in NAG. Releasing a weak electric current to stimulate selected brain areas may induce favorable effects on the autonomic control to the heart in highly fit subjects

Drug abusers have impaired cerebral oxygenation and cognition during exercise

Sem informaçãoBackground: Individuals with Substance Use Disorder (SUD) have lower baseline metabolic activity of the prefrontal cortex (PFC) associated with impairment of cognitive functions in decisionmaking and inhibitory control. Aerobic exercise has shown to improve PFC function and cognitive performance, however, its effects on SUD individuals remain unclear. Purpose: To verify the cognitive performance and oxygenation of the PFC during an incremental exercise in SUD individuals. Methods: Fourteen individuals under SUD treatment performed a maximum graded exercise test on a cycle ergometer with continuous measurements of oxygen consumption, PFC oxygenation, and inhibitory control (Stroop test) every two minutes of exercise at different intensities. Fifteen non-SUD individuals performed the same protocol and were used as control group. Results: Exercise increased oxyhemoglobin (O(2)Hb) and total hemoglobin (tHb) by 9% and 7%, respectively. However, when compared to a non-SUD group, this increase was lower at high intensities (p< 0.001), and the inhibitory cognitive control was lower at rest and during exercise (p< 0.007). In addition, PFC hemodynamics during exercise was inversely correlated with inhibitory cognitive performance (reaction time) (r = -0.62, p = 0.001), and a lower craving perception for the specific abused substance (p = 0.0189) was reported immediately after exercise. Conclusion: Despite SUD individuals having their PFC cerebral oxygenation increased during exercise, they presented lower cognition and oxygenation when compared to controls, especially at elevated intensities. These results may reinforce the role of exercise as an adjuvant treatment to improve PFC function and cognitive control in individuals with SUD.1211115Sem informaçãoSem informaçãoSem informaçã

Effect of caffeine intake on critical power model parameters determined on a cycle ergometer

The aim of this study was to evaluate the effect of caffeine intake on critical power model parameters determined on a cycle ergometer. Eight male subjects participated in this study. A double-blind protocol consisting of the intake of pure caffeine (6 mg/kg) or placebo (maltodextrin) 60 min before testing was used. Subjects were submitted to four constant-load tests on a cycle ergometer. These tests were conducted randomly in the caffeine and placebo groups [checar] at intensities of 80, 90, 100 and 110% maximum power at a rate of 70 rpm until exhaustion to determine the critical power. As a criterion for stopping the test was adopted any rate fall without recovery by more than five seconds. The critical power and anaerobic work capacity were obtained by nonlinear regression and fitting of the curve to a hyperbolic power-time model. The Shapiro-Wilk test and paired Student t-test were used for statistical analysis. No significant differences in critical power were observed between the caffeine and placebo groups (192.9 ± 31.3 vs 197.7 ± 29.4 W, respectively). The anaerobic work capacity was significantly higher in the caffeine group (20.1 ± 5.2 vs 16.3 ± 4.2 W, p<0.01). A high association (r²) was observed between the caffeine and placebo conditions (0.98 ± 0.02 and 0.99 ± 0.0, respectively). We conclude that caffeine intake did not improve critical power performance but increased anaerobic work capacity by influencing performance at loads of higher intensity and shorter duration.O objetivo do presente estudo foi verificar o efeito da ingestão de cafeína sobre os parâmetros do modelo de potência crítica determinado em cicloergômetro. Participaram do estudo oito sujeitos do sexo masculino. A ingestão de cafeína pura (6 mg.kg-1) ou placebo (maltodextrina) foi realizada através de protocolo duplo-cego, 60 minutos antes dos testes. Para determinação da potência crítica, os sujeitos foram submetidos a quatro testes de cargas constantes em cicloergômetro, realizados aleatoriamente, nos momentos cafeína e placebo, nas intensidades de 80, 90, 100 e 110% da potência máxima, a uma cadência de 70 rpm até a exaustão. A potência crítica e a capacidade de trabalho anaeróbio foram obtidas através de regressão não linear e ajuste de curva para o modelo hiperbólico potência-tempo. Para o tratamento estatístico, utilizaram-se-se o teste de Shapiro Wilk e o teste t de Student pareado. Não foram encontradas diferenças significativas na potência crítica nas condições cafeína e placebo (192,9 ± 31,3 vs 197,7 ± 29,4 W, respectivamente). A capacidade de trabalho anaeróbio foi significativamente maior na condição cafeína (20,1 ± 5,2 vs 16,3 ± 4,2 W, p< 0,01). Foi, ainda, obtido um alto valor de associação (r²) entre as condições cafeína e placebo (0,98± 0,02 e 0,99± 0,0). Através dos resultados obtidos, concluiu-se que a ingestão de cafeína não proporcionou melhorias no desempenho da potência crítica, entretanto, elevou os valores da capacidade de trabalho anaeróbio por influenciar o desempenho nas cargas de maior intensidade e menor duração.495

Efeito da ingestão de cafeína sobre o limiar de esforço percebido (LEP)

Caffeine is an ergogenic substance used to enhance sports performance. With central and peripheral effects, it may influences the perception of fatigue during exhaustive efforts with central and peripheral effects. The present study aimed to investigate the effects of caffeine ingestion on the perceived exertion threshold (PET). After completing maximum work load (Wmax) test on cycling ergometer, eight men executed four constant load tests (80, 90, 100 and 110% of Wmax) under caffeine (CAF) or placebo (PLA) ingestion for PET determination. The “t” Student paired test was used to compare PET under the analyzed conditions. There were no significant differences between CAF and PLA conditions for PET. However, during 100 and 110% constant load tests, CAF conditions presented longer exhausting time (P < 0,01) and the tests between 80% and 100% presented lower increasing ratings of perceived exertion (RPE) (P < 0,01). According to the results, it is possible to conclude that PET was not modified with CAF supplementation, even with higher performance during the most intensive tests and attenuation of the increasing rate of RPE in 80% and 100% loads.A cafeína é substância ergogênica utilizada para aprimorar o rendimento esportivo. Com efeitos centrais e periféricos, pode interferir na percepção de fadiga durante esforços exaustivos. O presente estudo objetivou investigar o efeito da ingestão de cafeína sobre o limiar de esforço percebido (LEP). Após estabelecer a carga máxima de trabalho (Wmax) por teste incremental em cicloergômetro, oito homens realizaram quatro testes de carga constante (80, 90, 100 e 110% da Wmax) sob ingestão de cafeína (CAF) ou placebo (PLA) para determinação do LEP. Para contrastar os dados, utilizou-se o teste “t” de Student pareado. Não foram encontradas diferenças significativas entre os valores de LEP em nenhuma das condições, porém, na condição CAF os testes constantes de 100 e 110% apresentaram maior tempo de exaustão (P < 0,01), e os testes de 80 e 100% apresentaram menor taxa de aumento da percepção subjetiva de esforço (PSE) (P < 0,01). De acordo com os resultados, é possível concluir que o LEP não foi modificado com a suplementação de CAF, mesmo com desempenho superior durante os testes mais intensos e atenuação da taxa de aumento da PSE nas cargas 80 e 100%