Influência do índice glicêmico da refeição pré-exercício sobre a glicemia e parâmetros cardiometabólicos durante exercício aeróbico matinal
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2013-03-08
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Universidade Federal de Viçosa
Resumo
A literatura estabelece que uma alimentação realizada com três horas prévias ao exercício é recomendada para fornecer energia, produzir um adequado esvaziamento gástrico e manter níveis normoglicêmicos durante a atividade (Ribeiro et al., 2005), assim como adotando duas horas prévias (Chen et al., 2009; Wong et al., 2009). Porém, para a prática física matinal essa conduta não reflete a realidade, já que o tempo prévio se torna restrito devido ao período de sono, o que pode levar o praticante a se exercitar em jejum ou se alimentar muito próximo à atividade, estando em ambas às situações sujeito a um quadro de hipoglicemia. O objetivo geral desta dissertação foi acompanhar e avaliar a resposta glicêmica 30 minutos antes e durante uma atividade em cicloergômetro com 1 hora de duração, após três procedimentos nutricionais de café da manhã : a) alto índice glicêmico (AIG); b) baixo índice glicêmico (BIG); c) em estado de jejum, administrando dois tipos de hidratação: água e bebida carboidratada com concentração de 60 g/L. Os objetivos específicos foram monitorar e avaliar o comportamento dos gases sanguíneos antes e durante o exercício físico, estabelecer correlações de possíveis mudanças desses com os parâmetros cardiorrespiratórios, avaliar a oxidação de substratos durante exercício, analisar hematócrito, hemoglobina, cálcio, sódio, potássio, lactato e avaliar o balanço hídrico. No primeiro estudo foi realizada uma consulta na base de dados PubMed, utilizando os descritores: aerobic exercise, glicemic index e glycemia, de forma combinada. Foram adotados como critérios de inclusão, artigos originais, publicados em inglês nos últimos cinco anos e realizados com humanos, e como critério de exclusão, amostra não saudável e exercício sem predominância aeróbica. Foram selecionados 11 artigos, os quais variavam quanto ao sexo da amostra e seu condicionamento, o tipo de exercício selecionado, assim como sua duração e intensidade, o valor de IG adotado, e o tempo prévio de ingestão alimentar de 15 minutos a três horas. De acordo com os resultados, alimentos de baixo índice glicêmico causam menor alteração glicêmica pós-prandial o que pode acarretar em um comportamento mais estável ao longo do exercício, tornando-se uma estratégia nutricional mais conservadora para a população em geral, além disso, deve-se destacar que uma refeição oferecida entre 15 e 45 minutos antes do início do exercício pode não ser o mais indicado, devido ao pico de ação da insulina ocorrer normalmente nesse período, o que somado à ação da contração muscular poderia desencadear um quadro de hipoglicemia de rebote. Nenhum dos estudos relacionados na revisão abordou esse tempo prévio. No segundo estudo 12 homens saudáveis e fisicamente ativos realizaram quatro testes experimentais, sendo dois com refeições pré-exercício, de AIG e BIG, e dois realizados em estado de jejum diferenciados pela hidratação, água (H2O) e bebida carboidratada (CHO). Cada teste consistiu de um período de repouso pré-exercício de 30 minutos, seguido por 60 minutos de cicloergômetro com carga contínua equivalente a 60% do consumo máximo de oxigênio extrapolado (VO2MaxExt). Durante o exercício os participantes eram hidratados a cada 15 minutos, sendo 3mL por kg de peso corporal. Não houve diferença na oxidação de substratos, observou-se uma menor alteração glicêmica pós-prandial causada pela refeição de BIG, porém, não significativa, e uma elevação dos níveis de potássio no final do exercício após a refeição de BIG, sendo significativa em relação ao jejum CHO. Além disso, houve uma manutenção da glicemia em níveis estáveis e mais altos durante o exercício em relação aos demais no procedimento de jejum CHO. O desenho experimental do terceiro estudo foi o mesmo descrito no trabalho anterior, sendo, porém, realizada coleta de amostras sanguíneas para análise de lactato, pH, PCO2, PO2, TCO2, HCO3, BE e SO2em jejum, imediatamente antes do consumo do café da manhã , assim como 15 e 30 minutos após seu consumo. Durante o exercício, foram obtidas amostras em intervalos de 20 minutos até o final dos 60 minutos de exercício, assim como os parâmetros cardiorrespiratórios. Os resultados demonstraram que os quatro procedimentos experimentais foram capazes de manter os parâmetros cardiorrespiratórios e hemogasométricos dos participantes, o que provavelmente ocorreu devido à manutenção do estado de hidratação. Dessa forma, diante das evidências científicas apontadas no primeiro estudo de que alimentos de BIG causam menor alteração glicêmica pós-prandial, esta parece ser uma estratégia nutricional mais conservadora para a população em geral. Este fato foi comprovado no segundo trabalho e reforçado pelo terceiro, pois independente do procedimento nutricional adotado em conjunto com uma hidratação de 3 mL/kg de peso corporal a cada 15 minutos, não houve alterações nos parâmetros cardiorrespiratórios e gases sanguíneos. Além disso, quando realizado em jejum, a hidratação com bebida carboidratada parece minimizar o risco hipoglicêmico advindo desse estado.
The literature states that a feed conducted with a three hour prior to exercise is suitable for powering an adequate gastric emptying and maintain during the same normoglycemic (Ribeiro et al., 2005) and 2 hours (Chen et al. 2,009 ; Wong et al. 2009). But for practice this morning physical conduct does not reflect reality, since the previous time becomes restricted, which may lead the practitioner to exercise fasting or eating very close to the activity, being in both situations subject to a framework hypoglycemia. The aim of this thesis was to monitor and evaluate the glycemic response 30 minutes before and during an activity cycle ergometer with 1 hour, after three procedures nutritional "breakfast": a) a high glycemic index, b) low glycemic index; c) in the fasting state, administering two kinds of hydration: water and carbohydrate drink with a concentration of 60 g/L. The specific objectives were to monitor and evaluate the behavior of blood gases before and during exercise, establish correlations of thesewith possible changes cardiorespiratory parameters, assess substrate oxidation during exercise, analyze hematocrit, hemoglobin, calcium, sodium, potassium, lactate and evaluate the water balance. The first study was conducted in a query PubMed database using the keywords: aerobic exercise, glicemic and glycemia index, combined. Were adopted as inclusion criteria, original articles, published in English in the last five years and performed with humans, and as exclusion criteria, sample unhealthy and exercise withoutpredominance aerobic. We selected 11 articles, which varied by gender of the sample and its conditioning, the type of exercise selected, as well as its duration and intensity, the value of IG adopted, and the time prior to food intake from 15 minutes to three hours. According to the results, low glycemic foods cause lower postprandial glycemic alterations which may result in a more stable throughout the year, making it a more conservative nutritional strategy for the general population, it should also be noted that a meal provided between 15 and 45 minutes before the start of the year may not be the most suitable, due to peak insulin action usually occurs during this period, which together with the effects of muscle contraction could trigger a framework of hypoglycemia rebound. None of the studies listed in this review addressed prior time. In the second study twelve men healthy and physically active performed four experimental tests, two with pre-exercise meals, high GI (AIG) and low GI (BIG), and two were conducted in the fasting state differentiated by hydration, water (H2O) and carbohydrate drink (CHO). Each test consisted of a rest period prior to exercise for 30 minutes, followed by 60 minutes of cycle ergometer with continuous load equivalent to 60% of maximal oxygen uptake extrapolated (VO2MaxExt). During exercise participants were hydrated every 15 minutes, and 3mL per kg bodyweight. There was no difference in substrate oxidation, there was a lower postprandial glycemic alterations caused by BIG meal, although not significant, and a high potassium levels at year-end after the BIG meal, being significant in relation to CHO fasting. In addition, there was a maintenance of blood glucose levels stable and higher during exercise in relation to other procedure in fasting CHO. In the third study was carried collection of blood samples for analysis of lactate, pH, PCO2, PO2, TCO2, HCO3, BE and SO2 fasting, immediately before consumption of the "breakfast", like 15 and 30 minutes after consumption .During the exercise, samples were collected at intervals of 20 minutes until the end of 60 minutes of exercise, as well as the cardiorespiratory parameters. The results showed that the four experimental procedures were able to maintain cardiorespiratory parameters and arterial blood gases of the participants, which was probably due to the maintenance of hydration status. Thus, given the evidence cited in the first study that BIG foods cause less postprandial glycemic change, this seems to be a more conservative nutritional strategy for the general population. This fact was confirmed in the second job and the third reinforced therefore independent of nutritional procedure adopted in conjunction with a hydration of 3 mL/kg of body weight every 15 minutes, no changes in cardiorespiratory parameters and blood gases. Furthermore, when performed on fasting, hydration with carbohydrate drink hypoglycemic seems to minimize the risk arising that state.
The literature states that a feed conducted with a three hour prior to exercise is suitable for powering an adequate gastric emptying and maintain during the same normoglycemic (Ribeiro et al., 2005) and 2 hours (Chen et al. 2,009 ; Wong et al. 2009). But for practice this morning physical conduct does not reflect reality, since the previous time becomes restricted, which may lead the practitioner to exercise fasting or eating very close to the activity, being in both situations subject to a framework hypoglycemia. The aim of this thesis was to monitor and evaluate the glycemic response 30 minutes before and during an activity cycle ergometer with 1 hour, after three procedures nutritional "breakfast": a) a high glycemic index, b) low glycemic index; c) in the fasting state, administering two kinds of hydration: water and carbohydrate drink with a concentration of 60 g/L. The specific objectives were to monitor and evaluate the behavior of blood gases before and during exercise, establish correlations of thesewith possible changes cardiorespiratory parameters, assess substrate oxidation during exercise, analyze hematocrit, hemoglobin, calcium, sodium, potassium, lactate and evaluate the water balance. The first study was conducted in a query PubMed database using the keywords: aerobic exercise, glicemic and glycemia index, combined. Were adopted as inclusion criteria, original articles, published in English in the last five years and performed with humans, and as exclusion criteria, sample unhealthy and exercise withoutpredominance aerobic. We selected 11 articles, which varied by gender of the sample and its conditioning, the type of exercise selected, as well as its duration and intensity, the value of IG adopted, and the time prior to food intake from 15 minutes to three hours. According to the results, low glycemic foods cause lower postprandial glycemic alterations which may result in a more stable throughout the year, making it a more conservative nutritional strategy for the general population, it should also be noted that a meal provided between 15 and 45 minutes before the start of the year may not be the most suitable, due to peak insulin action usually occurs during this period, which together with the effects of muscle contraction could trigger a framework of hypoglycemia rebound. None of the studies listed in this review addressed prior time. In the second study twelve men healthy and physically active performed four experimental tests, two with pre-exercise meals, high GI (AIG) and low GI (BIG), and two were conducted in the fasting state differentiated by hydration, water (H2O) and carbohydrate drink (CHO). Each test consisted of a rest period prior to exercise for 30 minutes, followed by 60 minutes of cycle ergometer with continuous load equivalent to 60% of maximal oxygen uptake extrapolated (VO2MaxExt). During exercise participants were hydrated every 15 minutes, and 3mL per kg bodyweight. There was no difference in substrate oxidation, there was a lower postprandial glycemic alterations caused by BIG meal, although not significant, and a high potassium levels at year-end after the BIG meal, being significant in relation to CHO fasting. In addition, there was a maintenance of blood glucose levels stable and higher during exercise in relation to other procedure in fasting CHO. In the third study was carried collection of blood samples for analysis of lactate, pH, PCO2, PO2, TCO2, HCO3, BE and SO2 fasting, immediately before consumption of the "breakfast", like 15 and 30 minutes after consumption .During the exercise, samples were collected at intervals of 20 minutes until the end of 60 minutes of exercise, as well as the cardiorespiratory parameters. The results showed that the four experimental procedures were able to maintain cardiorespiratory parameters and arterial blood gases of the participants, which was probably due to the maintenance of hydration status. Thus, given the evidence cited in the first study that BIG foods cause less postprandial glycemic change, this seems to be a more conservative nutritional strategy for the general population. This fact was confirmed in the second job and the third reinforced therefore independent of nutritional procedure adopted in conjunction with a hydration of 3 mL/kg of body weight every 15 minutes, no changes in cardiorespiratory parameters and blood gases. Furthermore, when performed on fasting, hydration with carbohydrate drink hypoglycemic seems to minimize the risk arising that state.
Descrição
Palavras-chave
Nutrição esportiva, Índice glicêmico, Bebida carboidratada, Exercício aeróbico, Sports nutrition, Glycemic index, Carbohydrate beverage, Aerobic Exercise
Citação
FARIA, Valéria Cristina de. Influence of glycemic index of pre-exercise meal on blood glucose levels and cardiometabolic parameters during morning aerobic exercise. 2013. 98 f. Dissertação (Mestrado em Aspectos sócio-culturais do movimento humano; Aspectos biodinâmicos do movimento humano) - Universidade Federal de Viçosa, Viçosa, 2013.