Suplementação de nitrato e sua relação com a formação de óxido nítrico e exercício físico

A ingesto de nitrato vem crescendo em popularidade no meio esportivo. Esta reviso objetiva esclarecer os mecanismos responsveis pelo efeito da suplementao de nitrato relacionadas ao xido ntrico, bem como descrever os efeitos agudos e crnicos da suplementao com nitrato sobre o desempenho. O xido ntrico um radical livre endgeno de meia vida curta e contribui de forma significativa na regulao de muitas funes corporais tais como: contratilidade muscular, metabolismo energtico, mensageiro intercelular, citotoxicidade mediada por macrfagos, inibio da agregao plaquetria, presso arterial, fluxo sanguneo e respirao mitocondrial. A suplementao com nitrato aumenta a disponibilidade de xido ntrico no organismo, este por sua vez age sobre a mitocndria promovendo efeitos importantes no consumo de oxignio durante o exerccio. Tem sido demonstrado que a suplementao diettica com nitrato acarreta aumento no tempo de exausto durante exerccios de alta intensidade, melhora no desempenho em exerccios contra relgio e promove reduo significativa no consumo de oxignio pulmonar em intensidades submximas. Por outro lado, apesar de haver tendncia ao uso de suco de beterraba, no existe consenso em relao forma de administrao de nitrato, tampouco conformidade quanto a melhor dose resposta

Can carbohydrate mouth rinse improve performance during exercise? A systematic review

The purpose of this review was to identify studies that have investigated the effect of carbohydrate (CHO) mouth rinse on exercise performance, and to quantify the overall mean difference of this type of manipulation across the studies. The main mechanisms involving the potential benefit of CHO mouth rinse on performance was also explored. A systematic review was conducted in the following electronic databases: PubMed, SciELO, Science Direct, MEDLINE, and the Cochrane Library (Cochrane Central Register of Controlled Trials), without limit of searches. Eleven studies were classified as appropriate and their results were summarized and compared. In nine of them, CHO mouth rinse increased the performance (range from 1.50% to 11.59%) during moderate- to high-intensity exercise (~75% Wmax or 65% VO2max, ~1 h duration). A statistical analysis to quantify the individual and overall mean differences was performed in seven of the 11 eligible studies that reported power output (watts, W) as the main performance outcome. The overall mean difference was calculated using a random-effect model that accounts for true variation in effects occurring in each study, as well as random error within a single study. The overall effect of CHO mouth rinse on performance was significant (mean difference = 5.05 W, 95% CI 0.90 to 9.2 W, z = 2.39, p = 0.02) but there was a large heterogeneity between the studies (I2 = 52%). An activation of the oral receptors and consequently brain areas involved with reward (insula/operculum frontal, orbitofrontal cortex, and striatum) is suggested as a possible physiological mechanism responsible for the improved performance with CHO mouth rinse. However, this positive effect seems to be accentuated when muscle and liver glycogen stores are reduced, possibly due to a greater sensitivity of the oral receptors, and require further investigation. Differences in duration of fasting before the trial, duration of mouth rinse, type of activity, exercise protocols, and sample size may account for the large variability between the studies

Can Carbohydrate Mouth Rinse Improve Performance during Exercise? A Systematic Review

The purpose of this review was to identify studies that have investigated the effect of carbohydrate (CHO) mouth rinse on exercise performance, and to quantify the overall mean difference of this type of manipulation across the studies. The main mechanisms involving the potential benefit of CHO mouth rinse on performance was also explored. A systematic review was conducted in the following electronic databases: PubMed, SciELO, Science Direct, MEDLINE, and the Cochrane Library (Cochrane Central Register of Controlled Trials), without limit of searches. Eleven studies were classified as appropriate and their results were summarized and compared. In nine of them, CHO mouth rinse increased the performance (range from 1.50% to 11.59%) during moderate- to high-intensity exercise (~75% Wmax or 65% VO(2)max, ~1 h duration). A statistical analysis to quantify the individual and overall mean differences was performed in seven of the 11 eligible studies that reported power output (watts, W) as the main performance outcome. The overall mean difference was calculated using a random-effect model that accounts for true variation in effects occurring in each study, as well as random error within a single study. The overall effect of CHO mouth rinse on performance was significant (mean difference = 5.05 W, 95% CI 0.90 to 9.2 W, z = 2.39, p = 0.02) but there was a large heterogeneity between the studies (I(2) = 52%). An activation of the oral receptors and consequently brain areas involved with reward (insula/operculum frontal, orbitofrontal cortex, and striatum) is suggested as a possible physiological mechanism responsible for the improved performance with CHO mouth rinse. However, this positive effect seems to be accentuated when muscle and liver glycogen stores are reduced, possibly due to a greater sensitivity of the oral receptors, and require further investigation. Differences in duration of fasting before the trial, duration of mouth rinse, type of activity, exercise protocols, and sample size may account for the large variability between the studies

Procedimentos metodológicos empregados em questionários de frequência alimentar elaborados no Brasil: uma revisão sistemática

Esta revisão teve como objetivo analisar e discutir os procedimentos metodológicos empregados nos Questionários de Frequência Alimentar elaborados no Brasil. Foram consultadas as bases de dados PubMed, SciELO, Lilacs, IBECS, MedLine e Cochrane Library, e encontrados vinte e dois Questionários de Frequência Alimentar elaborados para populações brasileiras. Entre os Questionários de Frequência Alimentar encontrados 50% deles (n=11) foram elaborados a partir de recordatório de 24 horas, 27,27% (n=6) de Questionários de Frequência Alimentar pré-existentes, 13,63% (n=3) de registro alimentar e 9,09% (n=2) de outras fontes; 72,72% (n=16) apresentaram listas com 50 a 100 itens, número ideal. Quanto ao tipo, 45,45% (n=10) eram quantitativos, 45,45% (n=10) semiquantitativos e 9,09% (n=2) qualitativos. Apenas 27,27% (n=6) relataram teste em estudo-piloto e apenas 45,45% (n=10) referiram teste de validação ou validação e reprodutibilidade. Quanto à faixa etária, apenas 36,36% (n=8) dos Questionários de Frequência Alimentar apresentavam público-alvo específico: crianças, adolescentes ou adultos. O maior número de Questionários de Frequência Alimentar (54,54%; n=12) foi desenvolvido na região Sudeste, especialmente no estado de São Paulo. A revisão da literatura permitiu conhecer os Questionários de Frequência Alimentar elaborados para a população brasileira e suas respectivas metodologias, público-alvo, bem como sua distribuição em termos de região do País. Embora exista uma orientação em termos de proposta metodológica de elaboração aqui discutida, há algum distanciamento em relação ao recomendado que deve ser observado pelos pesquisadores da área, ainda que haja uma maioria de procedimentos adequados aos métodos pressupostos