While training for a triathlon, a 25-year-old female follows a high-carbohydrate diet that provides for adequate glycogen and fat synthesis. When she begins the competition, fatty acid synthesis stops. The best explanation for this is a decrease in which of the following?

Question

Quizplus · Accepted Answer

During intense exercise, the demand for ATP increases, leading to a shift in metabolic pathways. The pentose phosphate pathway (PPP) is less active during exercise because the focus is on generating ATP through glycolysis and oxidative phosphorylation, rather than producing NADPH for fatty acid synthesis.  Fatty acid synthesis requires NADPH derived from the PPP via the oxidation of G6P. During strenuous exercise the vast majority of the glucose is shunted into glycolysis for complete oxidation. Therefore, little G6P is available for the PPP.

While Training for a Triathlon, a 25-Year-Old Female Follows a High-Carbohydrate