In rats, the reversal of exercise-enhanced insulin sensitivity following carbohydrate refeeding occurs independently of muscle glycogen supercompensation, as glycogen synthase 1 knockdown blocks glycogen synthesis without preventing the loss of insulin sensitivity.

After exercise, eating a lot of carbohydrates causes excess sugar to flow into a specific biochemical pathway in muscle cells. This pathway modifies key proteins involved in insulin signaling by adding sugar molecules to them. These modifications block the signal that tells muscle cells to bring glucose transporters to their surface. Without those transporters on the surface, muscle cells cannot take in glucose in response to insulin, so insulin sensitivity drops.