Efeito do índice glicêmico dos alimentos no metabolismo energético em ciclistas

• Autor(a) principal: Cocate, Paula Guedes
• Data de Publicação: 2007
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2702
• topic: Metabolismo energético; Índice glicêmico; Atletas; Composição corporal; Energy metabolism; Glycemic index; Athletes; Body composition; CNPQ::CIENCIAS DA SAUDE::NUTRICAO

The purpose of the present study was to evaluate the effect of the consumption of loads differing in glycemic index (GI), presenting similar macronutrients composition and energy density, in the level of some biochemical parameters (glucose, insulin, free fatty acids, and lactate), in the resting metabolic rate and in the energetic substrate utilization in the post-prandial interval (PP), during and after the exercise has been done. Participated in the study 15 male cyclists, aged 24.4 ± 3.7 years, body mass index of 21,97±1,46 kg/m2, and VO2máx of 70,00 ± 5,32 mL(kg.min)-1. The volunteers participated in two experimental sessions in a random order, when they ingested within 15 minutes 2 daily high glycemic index (HGI) or low glycemic index (LGI) meals (breakfast, afternoon lunch), providing 1/3 of their resting energetic requirements, during 4 consecutive days. After 90 minutes PP, participants underwent an 85 to 95% of the maximum cardiac frequency cycloergometric exercise, during three stages of 10 minutes each. In the 1o and 4o day of each experimental session, after 12 hours fasting, energy expenditure, energetic substrate oxidation rate in the PP interval and the level of the biochemical parameters in the PP interval and during the exercise were evaluated. The consumption of HIG loads lead to higher areas under the glycemic and insulinemic curves in the PP than the ingestion of LGI loads. This difference was not sufficient to affect the glycemia during the exercise. While consumption of HGI loads resulted in higher fat oxidation, ingestion of LGI loads lead to higher carbohydrate oxidation during the 90 minutes PP. These results may have occurred due tot eh high fructose content of the LGI loads, which favors carbohydrate oxidation. The higher fat oxidation observed after the consumption of HGI loads, did not affect the levels of free fatty acids in comparison to the ingestion of the LGI loads. These results suggest that despite the higher fat oxidation associated to the consumption of HGI loads, there was a higher utilization of free fatty acids during the 120 minutes PP, maintaining these levels constant during the 90 minutes of assessment of these parameters. The consumption of HGI or LG loads did not affect the levels of lactate during the 30 minutes of exercise (100 to 120 minutes PP). These results indicate that although there was a higher carbohydrate oxidation after the consumption of the LGI loads, glycogen breakdown and the consequent lactate production during the exercise were not affected by the GI. The consumption of foods differing the GI lead to an increase in energy expenditure in the PP in comparison to what was observed in fasting state. However, this increase was not affected by the GI presented by the ingested loads. Besides, no difference was observed in body composition and in the anthropometric data between the first and the fourth day in which the HGI or LGI loads were consumed. In conclusion, these results indicate that the consumption of high fructose content LGI foods do not result in an increase in fat oxidation rate, and therefore their consumption should not be indicated when a control in body fat is desired. It can also be concluded that such foods are not better than the HGI foods to provide the energy required during the exercise.