Valéria Cristina de Faria

Influência do índice glicêmico na glicemia em exercício físico aeróbico

Abstract: Objective: Evaluate the influence of glycemic index (GI) on the glycemic response before and during the physical exercise after to different experimental sessions pre-exercise. Methods: Twelve adult males performed three experimental sessions pre-exercise: of high glycemic index (HGI); of low glycemic index (LGI); In condition of fast, although this one take two different ways of hydration while the exercise: water and carbohydrate drink. Results: During the repose period, the type of meal, even the HGI and also the LGI, interfered on glycemic’s behavior, both tendency to the “Rebound Effect”. During the exercise, it was not observed differences in glycemic answers between the four tested actions, although the intervention with CHO drink maintained constant blood along all 60 min of exercise. Conclusion: The GI is determinant in the glycemic response over an hour before exercise, but does not interfere in the glycemic response during the activity. Key Words: Dietary carbohydrates. Physical exercise. Fluid therapy. Blood glucose.

Metabolic response to different glycemic indexes of pre-exercise meal

INTRODUCAO: Para garantir o desempenho e a saude, o tipo de alimento e o tempo de ingestao pre-exercicio devem ser considerados pelos praticantes de atividade fisica matutina. Objetivo: Este estudo avaliou a resposta metabolica apos as refeicoes pre-exercicio com diferentes indices glicemicos (IG) e no estado de jejum, adotando diferentes tipos de hidratacao. METODOS: Doze homens realizaram quatro testes; dois com refeicoes pre-exercicio de alto IG (AIG) e baixo IG (BIG), e dois foram conduzidos em jejum com hidratacao: agua (H2O) e bebida carboidratada (CHO). Cada teste consistiu em 30 minutos de repouso antes do exercicio, seguidos por 60 minutos de bicicleta ergometrica com carga continua equivalente a 60% do consumo maximo de oxigenio extrapolado (VO2MaxExt). Durante o exercicio, os participantes foram hidratados a cada 15 minutos com 3 ml por kg de peso corporal. Durante cada teste, foram obtidas amostras de sangue venoso em jejum e em intervalos de 15 minutos durante o repouso, e a cada 20 minutos durante o exercicio. A analise de gases foi realizada em periodos de 5 minutos a cada 20 minutos de exercicio. RESULTADOS: Nao houve diferenca na oxidacao de substrato. Depois de 20 minutos de exercicio, os procedimentos de ingestao de alimentos pre-exercicio apresentaram comportamento semelhante, mostrando somente reducao dos niveis de glicemia em comparacao com os procedimentos em jejum (p < 0,01). Houve manutencao da glicemia em niveis estaveis e mais altos durante o exercicio com relacao aos outros testes no procedimento de jejum com CHO. CONCLUSAO: Os dados sugerem que, apesar do comportamento metabolico semelhante entre refeicoes de BIG e AIG, a adocao de uma refeicao de BIG antes do exercicio matinal parece ser uma pratica de alimentacao mais adequada devido a maior propensao de hipoglicemia de rebote apos a refeicao AIG e, quando o exercicio matinal e realizado em jejum, a hidratacao com CHO parece minimizar o risco hipoglicemico decorrente desse estado.INTRODUCTION: To ensure performance and health, the type of food and the time of pre-exercise ingestion should be considered by practitioners of morning physical activity. Objective: This study assessed the metabolic response after pre-exercise meals with different glycemic indexes (GI) and in the fasting state adopting different types of hydration. METHODS: Twelve men performed four experimental tests; two with pre-exercise meals of high GI (HGI) and low GI (LGI), and two were performed in the fasting state with hydration: water (H2O) and carbohydrate drink (CHO). Each test consisted of a pre-exercise rest period of 30 minutes followed by 60 minutes of cycle ergometer with continuous load equivalent to 60% of the extrapolated maximal oxygen consumption (VO2MaxExt). During the exercise, participants were hydrated every 15 minutes with 3mL per kg body weight. During each experimental test, venous blood samples were obtained for fasting and at 15-minute intervals during rest, and every 20 minutes during exercise. The gas analysis was carried out in periods of 5 minutes every 20 minutes of exercise. RESULTS: There was no difference in substrate oxidation. After 20 minutes of exercise, pre-exercise food intake procedures showed similar behavior, having only reduced blood glucose levels compared to fasting procedures (p<0.01). There was maintenance of blood glucose at stable and higher levels during exercise in relation to the other tests in the fast procedure with CHO. CONCLUSION: The data suggest that despite the similar metabolic behavior between LGI and HGI meals, the adoption of a LGI meal before the morning exercise seems to be a more suitable feeding practice due to higher tendency of rebound hypoglycemia after HGI meal and when morning exercise is performed on fasting, hydration with CHO seems to minimize the hypoglycemic risk arising from that state.

Índice glicêmico da refeição pré-exercício e metabolismo da glicose na atividade aeróbica

The glycemic index (GI) is a functional indicator that can be used to classify carbohydrates according to their glycemic and insulin response in relation to a known food, white bread or glucose. In the field of sports nutrition,it is mainly considered to constitute the meal prior to exercise, as it directly affects the postprandial glycemic response, and depending on certain factors, such as time prior to intake, there is the risk of rebound hypoglycemia during exercise. To elucidade, through a systematic review, which nutritional strategy is the most appropriate, employing pre-exercise meals of different glycemic indexes. The PubMed database was consulted using the combined keywords: aerobic exercise, glycemic index and glycemia. The inclusion criteria were original articles published in English in the last five years and performed with humans. Exclusion criteria were unhealthy subjects and non aerobic exercises. Eleven articles were selected, varying by gender of the sample and its conditioning, the type of exercise selected, as well as its duration and intensity, the IG value adopted, and the time prior to food intake from 15 minutes to three hours. Based on the recurrence of some results, low glycemic index foods cause fewer postprandial glycemic alterations which may entail a more stable behavior throughout the exercise, making it a more conservative nutritional strategy for the general population.O indice glicemico (IG) e um indicador funcional que pode ser usado para classificar carboidratos de acordo com sua resposta glicemica e insulinemica em relacao a um alimento conhecido, pao branco ou glicose. No ramo da nutricao esportiva, este e considerado principalmente para compor a refeicao pre-exercicio, pois afeta diretamente a resposta glicemica pos-prandial, e dependendo de alguns fatores, tais como o tempo previo de ingestao, existe o risco de hipoglicemia de rebote durante o exercicio. Elucidar, atraves de uma revisao sistematizada, qual estrategia nutricional e a mais adequada empregando refeicoes de diferentes indices glicemicos pre-exercicio. Foi consultada a base de dados PubMed, utilizando os descritores: aerobic exercise, glicemic index e glycemia, de forma combinada. Foram adotados como criterios de inclusao artigos originais, publicados em ingles nos ultimos cinco anos e realizados com humanos, e como criterio de exclusao, amostra nao saudavel e exercicio sem predominância aerobica. Foram selecionados 11 artigos, os quais variavam quanto ao genero da amostra e seu condicionamento, o tipo de exercicio selecionado, assim como sua duracao e intensidade, o valor de IG adotado, e o tempo previo de ingestao alimentar, de 15 minutos a tres horas. Pela recorrencia de alguns resultados, alimentos de baixo indice glicemico causam menor alteracao glicemica pos-prandial, o que pode acarretar em um comportamento mais estavel ao longo do exercicio, tornando-se uma estrategia nutricional mais conservadora para a populacao em geral.

Resposta metabólica a diferentes índices glicêmicos da refeição pré-exercício

INTRODUCAO: Para garantir o desempenho e a saude, o tipo de alimento e o tempo de ingestao pre-exercicio devem ser considerados pelos praticantes de atividade fisica matutina. Objetivo: Este estudo avaliou a resposta metabolica apos as refeicoes pre-exercicio com diferentes indices glicemicos (IG) e no estado de jejum, adotando diferentes tipos de hidratacao. METODOS: Doze homens realizaram quatro testes; dois com refeicoes pre-exercicio de alto IG (AIG) e baixo IG (BIG), e dois foram conduzidos em jejum com hidratacao: agua (H2O) e bebida carboidratada (CHO). Cada teste consistiu em 30 minutos de repouso antes do exercicio, seguidos por 60 minutos de bicicleta ergometrica com carga continua equivalente a 60% do consumo maximo de oxigenio extrapolado (VO2MaxExt). Durante o exercicio, os participantes foram hidratados a cada 15 minutos com 3 ml por kg de peso corporal. Durante cada teste, foram obtidas amostras de sangue venoso em jejum e em intervalos de 15 minutos durante o repouso, e a cada 20 minutos durante o exercicio. A analise de gases foi realizada em periodos de 5 minutos a cada 20 minutos de exercicio. RESULTADOS: Nao houve diferenca na oxidacao de substrato. Depois de 20 minutos de exercicio, os procedimentos de ingestao de alimentos pre-exercicio apresentaram comportamento semelhante, mostrando somente reducao dos niveis de glicemia em comparacao com os procedimentos em jejum (p < 0,01). Houve manutencao da glicemia em niveis estaveis e mais altos durante o exercicio com relacao aos outros testes no procedimento de jejum com CHO. CONCLUSAO: Os dados sugerem que, apesar do comportamento metabolico semelhante entre refeicoes de BIG e AIG, a adocao de uma refeicao de BIG antes do exercicio matinal parece ser uma pratica de alimentacao mais adequada devido a maior propensao de hipoglicemia de rebote apos a refeicao AIG e, quando o exercicio matinal e realizado em jejum, a hidratacao com CHO parece minimizar o risco hipoglicemico decorrente desse estado.INTRODUCTION: To ensure performance and health, the type of food and the time of pre-exercise ingestion should be considered by practitioners of morning physical activity. Objective: This study assessed the metabolic response after pre-exercise meals with different glycemic indexes (GI) and in the fasting state adopting different types of hydration. METHODS: Twelve men performed four experimental tests; two with pre-exercise meals of high GI (HGI) and low GI (LGI), and two were performed in the fasting state with hydration: water (H2O) and carbohydrate drink (CHO). Each test consisted of a pre-exercise rest period of 30 minutes followed by 60 minutes of cycle ergometer with continuous load equivalent to 60% of the extrapolated maximal oxygen consumption (VO2MaxExt). During the exercise, participants were hydrated every 15 minutes with 3mL per kg body weight. During each experimental test, venous blood samples were obtained for fasting and at 15-minute intervals during rest, and every 20 minutes during exercise. The gas analysis was carried out in periods of 5 minutes every 20 minutes of exercise. RESULTS: There was no difference in substrate oxidation. After 20 minutes of exercise, pre-exercise food intake procedures showed similar behavior, having only reduced blood glucose levels compared to fasting procedures (p<0.01). There was maintenance of blood glucose at stable and higher levels during exercise in relation to the other tests in the fast procedure with CHO. CONCLUSION: The data suggest that despite the similar metabolic behavior between LGI and HGI meals, the adoption of a LGI meal before the morning exercise seems to be a more suitable feeding practice due to higher tendency of rebound hypoglycemia after HGI meal and when morning exercise is performed on fasting, hydration with CHO seems to minimize the hypoglycemic risk arising from that state.

Respuesta metabólica a diferentes índices glucémicos de la ingestión de alimentos antes de los ejercicios

INTRODUCAO: Para garantir o desempenho e a saude, o tipo de alimento e o tempo de ingestao pre-exercicio devem ser considerados pelos praticantes de atividade fisica matutina. Objetivo: Este estudo avaliou a resposta metabolica apos as refeicoes pre-exercicio com diferentes indices glicemicos (IG) e no estado de jejum, adotando diferentes tipos de hidratacao. METODOS: Doze homens realizaram quatro testes; dois com refeicoes pre-exercicio de alto IG (AIG) e baixo IG (BIG), e dois foram conduzidos em jejum com hidratacao: agua (H2O) e bebida carboidratada (CHO). Cada teste consistiu em 30 minutos de repouso antes do exercicio, seguidos por 60 minutos de bicicleta ergometrica com carga continua equivalente a 60% do consumo maximo de oxigenio extrapolado (VO2MaxExt). Durante o exercicio, os participantes foram hidratados a cada 15 minutos com 3 ml por kg de peso corporal. Durante cada teste, foram obtidas amostras de sangue venoso em jejum e em intervalos de 15 minutos durante o repouso, e a cada 20 minutos durante o exercicio. A analise de gases foi realizada em periodos de 5 minutos a cada 20 minutos de exercicio. RESULTADOS: Nao houve diferenca na oxidacao de substrato. Depois de 20 minutos de exercicio, os procedimentos de ingestao de alimentos pre-exercicio apresentaram comportamento semelhante, mostrando somente reducao dos niveis de glicemia em comparacao com os procedimentos em jejum (p < 0,01). Houve manutencao da glicemia em niveis estaveis e mais altos durante o exercicio com relacao aos outros testes no procedimento de jejum com CHO. CONCLUSAO: Os dados sugerem que, apesar do comportamento metabolico semelhante entre refeicoes de BIG e AIG, a adocao de uma refeicao de BIG antes do exercicio matinal parece ser uma pratica de alimentacao mais adequada devido a maior propensao de hipoglicemia de rebote apos a refeicao AIG e, quando o exercicio matinal e realizado em jejum, a hidratacao com CHO parece minimizar o risco hipoglicemico decorrente desse estado.INTRODUCTION: To ensure performance and health, the type of food and the time of pre-exercise ingestion should be considered by practitioners of morning physical activity. Objective: This study assessed the metabolic response after pre-exercise meals with different glycemic indexes (GI) and in the fasting state adopting different types of hydration. METHODS: Twelve men performed four experimental tests; two with pre-exercise meals of high GI (HGI) and low GI (LGI), and two were performed in the fasting state with hydration: water (H2O) and carbohydrate drink (CHO). Each test consisted of a pre-exercise rest period of 30 minutes followed by 60 minutes of cycle ergometer with continuous load equivalent to 60% of the extrapolated maximal oxygen consumption (VO2MaxExt). During the exercise, participants were hydrated every 15 minutes with 3mL per kg body weight. During each experimental test, venous blood samples were obtained for fasting and at 15-minute intervals during rest, and every 20 minutes during exercise. The gas analysis was carried out in periods of 5 minutes every 20 minutes of exercise. RESULTS: There was no difference in substrate oxidation. After 20 minutes of exercise, pre-exercise food intake procedures showed similar behavior, having only reduced blood glucose levels compared to fasting procedures (p<0.01). There was maintenance of blood glucose at stable and higher levels during exercise in relation to the other tests in the fast procedure with CHO. CONCLUSION: The data suggest that despite the similar metabolic behavior between LGI and HGI meals, the adoption of a LGI meal before the morning exercise seems to be a more suitable feeding practice due to higher tendency of rebound hypoglycemia after HGI meal and when morning exercise is performed on fasting, hydration with CHO seems to minimize the hypoglycemic risk arising from that state.

Glycemic index of pre-exercise meal and glucose metabolism in aerobic physical activity

The glycemic index (GI) is a functional indicator that can be used to classify carbohydrates according to their glycemic and insulin response in relation to a known food, white bread or glucose. In the field of sports nutrition,it is mainly considered to constitute the meal prior to exercise, as it directly affects the postprandial glycemic response, and depending on certain factors, such as time prior to intake, there is the risk of rebound hypoglycemia during exercise. To elucidade, through a systematic review, which nutritional strategy is the most appropriate, employing pre-exercise meals of different glycemic indexes. The PubMed database was consulted using the combined keywords: aerobic exercise, glycemic index and glycemia. The inclusion criteria were original articles published in English in the last five years and performed with humans. Exclusion criteria were unhealthy subjects and non aerobic exercises. Eleven articles were selected, varying by gender of the sample and its conditioning, the type of exercise selected, as well as its duration and intensity, the IG value adopted, and the time prior to food intake from 15 minutes to three hours. Based on the recurrence of some results, low glycemic index foods cause fewer postprandial glycemic alterations which may entail a more stable behavior throughout the exercise, making it a more conservative nutritional strategy for the general population.O indice glicemico (IG) e um indicador funcional que pode ser usado para classificar carboidratos de acordo com sua resposta glicemica e insulinemica em relacao a um alimento conhecido, pao branco ou glicose. No ramo da nutricao esportiva, este e considerado principalmente para compor a refeicao pre-exercicio, pois afeta diretamente a resposta glicemica pos-prandial, e dependendo de alguns fatores, tais como o tempo previo de ingestao, existe o risco de hipoglicemia de rebote durante o exercicio. Elucidar, atraves de uma revisao sistematizada, qual estrategia nutricional e a mais adequada empregando refeicoes de diferentes indices glicemicos pre-exercicio. Foi consultada a base de dados PubMed, utilizando os descritores: aerobic exercise, glicemic index e glycemia, de forma combinada. Foram adotados como criterios de inclusao artigos originais, publicados em ingles nos ultimos cinco anos e realizados com humanos, e como criterio de exclusao, amostra nao saudavel e exercicio sem predominância aerobica. Foram selecionados 11 artigos, os quais variavam quanto ao genero da amostra e seu condicionamento, o tipo de exercicio selecionado, assim como sua duracao e intensidade, o valor de IG adotado, e o tempo previo de ingestao alimentar, de 15 minutos a tres horas. Pela recorrencia de alguns resultados, alimentos de baixo indice glicemico causam menor alteracao glicemica pos-prandial, o que pode acarretar em um comportamento mais estavel ao longo do exercicio, tornando-se uma estrategia nutricional mais conservadora para a populacao em geral.

Índice glicémico de la comida pre-ejercicio y metabolismo de la glucosa en la actividad aeróbica

The glycemic index (GI) is a functional indicator that can be used to classify carbohydrates according to their glycemic and insulin response in relation to a known food, white bread or glucose. In the field of sports nutrition,it is mainly considered to constitute the meal prior to exercise, as it directly affects the postprandial glycemic response, and depending on certain factors, such as time prior to intake, there is the risk of rebound hypoglycemia during exercise. To elucidade, through a systematic review, which nutritional strategy is the most appropriate, employing pre-exercise meals of different glycemic indexes. The PubMed database was consulted using the combined keywords: aerobic exercise, glycemic index and glycemia. The inclusion criteria were original articles published in English in the last five years and performed with humans. Exclusion criteria were unhealthy subjects and non aerobic exercises. Eleven articles were selected, varying by gender of the sample and its conditioning, the type of exercise selected, as well as its duration and intensity, the IG value adopted, and the time prior to food intake from 15 minutes to three hours. Based on the recurrence of some results, low glycemic index foods cause fewer postprandial glycemic alterations which may entail a more stable behavior throughout the exercise, making it a more conservative nutritional strategy for the general population.O indice glicemico (IG) e um indicador funcional que pode ser usado para classificar carboidratos de acordo com sua resposta glicemica e insulinemica em relacao a um alimento conhecido, pao branco ou glicose. No ramo da nutricao esportiva, este e considerado principalmente para compor a refeicao pre-exercicio, pois afeta diretamente a resposta glicemica pos-prandial, e dependendo de alguns fatores, tais como o tempo previo de ingestao, existe o risco de hipoglicemia de rebote durante o exercicio. Elucidar, atraves de uma revisao sistematizada, qual estrategia nutricional e a mais adequada empregando refeicoes de diferentes indices glicemicos pre-exercicio. Foi consultada a base de dados PubMed, utilizando os descritores: aerobic exercise, glicemic index e glycemia, de forma combinada. Foram adotados como criterios de inclusao artigos originais, publicados em ingles nos ultimos cinco anos e realizados com humanos, e como criterio de exclusao, amostra nao saudavel e exercicio sem predominância aerobica. Foram selecionados 11 artigos, os quais variavam quanto ao genero da amostra e seu condicionamento, o tipo de exercicio selecionado, assim como sua duracao e intensidade, o valor de IG adotado, e o tempo previo de ingestao alimentar, de 15 minutos a tres horas. Pela recorrencia de alguns resultados, alimentos de baixo indice glicemico causam menor alteracao glicemica pos-prandial, o que pode acarretar em um comportamento mais estavel ao longo do exercicio, tornando-se uma estrategia nutricional mais conservadora para a populacao em geral.