Hormonal
High carbohydrate availability during prolonged exercise enhances performance time and delays fatigue by maintaining higher carbohydrate combustion rates and slower plasma glucose decline compared to high fat diets.
For prolonged exercise, eating a high-carbohydrate diet for several days prior significantly extends your time to exhaustion compared to a high-fat diet. This is due to better maintenance of blood glucose and higher carbohydrate usage. Simply drinking glucose during exercise when you are already tired does not significantly extend your performance time, suggesting that pre-exercise fuel stores are critical.
Time to exhaustion was longer in CH- (106+/-5 min (S.E.)) than in F-expts. (64+/-6). During exercise, overall carbohydrate combustion rate, muscular glycogen depletion and glucose ma lactate concentrations, carbohydrate metabolites in plasma, and estimated rate of hepatic glucose production were higher, fat metabolites lower, and the decrease in plasma glucose slower in CH- than in F-expts.
Why this rating
Controlled crossover trial with clear metabolic and performance outcomes, though small sample size (n=7).
Source
The effect of different diets and of insulin on the hormonal response to prolonged exercise
H. Galbo et al. · Acta Physiologica Scandinavica · 1979
DOI 10.1111/j.1748-1716.1979.tb06438.x
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