I suspect it was just enough to deplete muscle glycogen stores.

In hepatocytes glucokinase (GK) and glucose-6-phosphatase (Glc-6-Pase)1 have converse effects on glucose 6-phosphate (and fructose 6-phosphate) levels. To establish whether hexose 6-phosphate regulates GK binding to its regulatory protein, we determined the effects of Glc-6-Pase overexpression on glucose metabolism and GK compartmentation. Glc-6-Pase overexpression (4- fold) decreased glucose 6-phosphate levels by 50% and inhibited glycogen synthesis and glycolysis with a greater negative control coefficient on glycogen synthesis than on glycolysis, but it did not affect the response coefficients of glycogen synthesis or glycolysis to glucose, and it did not increase the control coefficient of GK or cause dissociation of GK from its regulatory protein, indicating that in hepatocytes fructose 6-phosphate does not regulate GK translocation by feedback inhibition. GK overexpression increases glycolysis and glycogen synthesis with a greater control coefficient on glycogen synthesis than on glycolysis. On the basis of the similar relative control coefficients of GK and Glc-6-Pase on glycogen synthesis compared with glycolysis, and the lack of effect of Glc-6-Pase overexpression on GK translocation or the control coefficient of GK, it is concluded that the main regulatory function of Glc-6-Pase is to buffer the glucose 6-phosphate concentration. This is consistent with recent findings that hyperglycemia stimulates Glc-6-Pase gene transcription.

It is a particular risk if one starts a ride withouta full tank, so to speak, of muscle glycogen.

The second argument against fruit is more directly related to the above discussion on glycogen replenishment. To review, glucose is especially good for replenishing muscle glycogen but not liver glycogen. Fructose is the exact opposite; it can be used to replenish liver glycogen but not muscle glycogen.

Fructose/Galactose/Glycogen Flashcards | Quizlet

Ensuring maximal repletionof glycogen on multi day rides starts even before you get on the bike.

This type of fatigue is a particular risk at the elite athlete level where there may be multiple training sessions (or competitions) per day, and limited time to eat.It is important to maximize your total body glycogen stores by using dietary carbohydratesto your advantage - before, during, as well as after a ride.

Glycolysis, Gluconeogenesis and Glycogen Synthesis

Only the glycogen stored in the liver can be made accessible to other organs, and these hepatocytes have the highest concentration of it – roughly 3-5%, but up to 8% of the fresh weight in well fed state, or 100–120 g in an adult.

It differs from glycogen synthesis in …

There were no differences between diets in muscle glycogen storage over 24 h between equi-Caloric diets of carbohydrate alone (approx 10 grams of CHOper kg body wt per 24 hours and a mixed diet of CHO/Pro/fat.

Carbohydrates | Glycogen | Carbohydrates

In the muscles, glycogen is found in a much lower concentration (0.5-1% of the muscle mass), but the total amount exceeds that in liver because of the relatively large mass of muscle present in the body.
BIOC 212
Apnea = suspension of external breathing
F-1,6-BPase deficiency:
Elevated lactate
BIOC 212
Glycogen is a highly-branched polysaccharide of glucose that represents the sugar’s principal storage form in animal cells.

Glucose Supplies: Glycogen, Gluconeogenesis, & Disease …

The glucose is derived from three primary sources:
Lactate from anaerobic glycolysis is converted to pyruvate, then oxaloacetate, then malate for mitochondrial export, back to oxaloacetate, then PEP and onward to glucose.
BIOC 212
One of the most severe glycogen storage diseases – glycogen is found in very long chains, and has reduced solubility.