GLOSSARY

Fructose-1,6-Bisphosphatase (FBPase-1) catalyzes fructose-bisphosphate hydrolysis in gluconeogenesis.

For example, after training changes an enzyme result, first ask whether it was measured in blood, tissue or purified protein. Then assess assay conditions, nutrition and time since the last session alongside actual performance; this comparison helps distinguish a regulatory response from a nutritional deficiency or a presumed supplement need.

Gluconeogenesis makes glucose from lactate, glycerol and some amino acids, with major hepatic and context-dependent renal contributions. It costs energy and is not a simple reversal of all glycolysis. Even-chain fatty-acid acetyl units do not normally provide direct net human glucose; glycerol and other routes require separate treatment. Endogenous production does not automatically eliminate exercise fueling needs, particularly at high demand, and precursor availability is only one part of pathway regulation.

Endogenous glucose production includes glycogen breakdown and new synthesis rather than gluconeogenesis alone. Cellular production and release into blood differ because local use occurs. Contributions change with fasting and activity. Tracers and pool definitions matter; a stable blood glucose can coexist with high turnover. It does not mean fuel is unnecessary or glucose use has stopped, nor does one circulating concentration isolate hepatic versus renal contributions to supply.