The effect of a breakfast’s glycaemic index and type of hydration on metabolism and cycling performance: a crossover, randomized, controlled clinical trial. [El efecto del índice glucémico del desayuno y el tipo de hidratación en el metabolismo y el rendimiento del ciclismo: un ensayo clínico cruzado, aleatorizado y controlado].

Mariana de Melo Cazal, Rita de Cássia Gonçalves Alfenas, Maria do Carmo Gouveia Peluzio, Paulo Roberto dos Santos Amorim, Priscila Alvez Tomaz, João Carlos Bouzas Marins



The purpose of this study was to compare the effect of the glycaemic index of breakfast on metabolic parameters and performance of cyclists with different types of hydration (water or isotonic beverage). Twelve male recreational cyclists participated in four experimental trials where they consumed either a high glycaemic index (HGI) or low glycaemic index (LGI) meal, 30 min before exercise on a cycle ergometer. Exercise was performed at 70% maximal oxygen uptake for 90 min followed by a 6 km performance. During each trial, 3 body mass of either water or isotonic beverage was provided. The postprandial glycaemic response and areas under the blood glucose curve 30 min after ingestion were higher after the consumption of the HGI meals than that after the consumption of the LGI meals. The glycaemic response and carbohydrate oxidation during the trials with isotonic beverage consumption were higher than that in trials with water consumption during exercise (p<0.05). There was no significant difference on exercise performance among all trials (p=0.409). This study demonstrated that, despite significant metabolic changes, neither LGI nor HGI meals consumed for breakfast, 30 min before exercise on a cycle ergometer, affect subsequent cycling performance.


El objetivo de este estudio fue comparar desayunos con diferentes índices glucémicos y efecto del tipo de hidratación (agua o bebida isotónica) sobre los parámetros metabólicos y el rendimiento de los ciclistas. Doce ciclistas recreativos de sexo masculino participaron en cuatro pruebas experimentales en las que consumieron un desayuno de alto índice glucémico (AGI) o de bajo índice glucémico (BGI), 30 minutos antes del ejercicio en un cicloergómetro. El ejercicio se realizó a un 70%VO2max durante 90 minutos, seguido de 6 km al menor tiempo posible. Durante cada prueba, se suministraron 3 de masa corporal de agua o de bebida isotónica. La respuesta glucémica postprandial y las áreas bajo la curva de glucosa en sangre 30 min después de la ingesta fueron mayores tras el desayuno de AGI que tras el desayuno con BGI. La respuesta glucémica y la oxidación de carbohidratos durante los ensayos con consumo de bebidas isotónicas fueron mayores que en los ensayos con consumo de agua durante el ejercicio (p<0,05). No hubo diferencias significativas en el rendimiento del ejercicio entre todos los ensayos (p=0,409). Este estudio demostró que, a pesar de los cambios metabólicos significativos, ni las comidas BGI ni AGI consumidas en el desayuno, 30 min antes del ejercicio en cicloergómetro afectan al rendimiento final del ciclismo.


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Palabras clave/key words

glycaemic response; isotonic solutions; pre-exercise meal; carbohydrate; exercise; respuesta glucémica; soluciones isotónicas; desayuno; carbohidratos; ejercicio.

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RICYDE. Revista Internacional de Ciencias del Deporte

Publisher: Ramón Cantó Alcaraz
ISSN:1885-3137 - Periodicidad Trimestral / Quarterly
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