NUTRITION IN SPORT - Index of

Sugar
activation
Cleavage
SUBSTRATE
LEVEL
PHOSPHORYLATION
OF ADP
ATP
ADP
ADP
ATP
ADP
ATP
Glycolysis
glycolytic intermediates, but when this happens,
the associated hydrogen ions cause intracellular
pH to fall. Some lactate will diffuse into the extracellular
space and will eventually begin to accumulate
in the blood. The lactate that leaves the
biochemistry of exercise 25
Glucose
Glycogen
ATP Hexokinase
Pi Glycogen
ADP
phosphorylase
Phosphoglucomutase
Glucose-6-phosphate
Glucose-1-phosphate
Fructose-6-phosphate
Glucose-phospate isomerase
6-phosphofructokinase
Fructose-1,6-bisphosphate
Aldolase
Dihydroxyacetone phosphate Glyceraldehyde-3-phosphate
Triose-phosphate
isomerase
Lactate dehydrogenase
Lactate
NADH
NAD +
P i , NAD +
NADH
1,3-diphosphoglycerate
3-phosphoglycerate
2-phosphoglycerate
Phosphoglycerate kinase
Phosphoglyceromutase
Enolase
Phosphoenolpyruvate
Pyruvate
Pyruvate kinase
NAD +
NADH
CoA
Glyceraldehyde-phosphate
dehydrogenase
Mitochondrion
Pyruvate dehydrogenase
Cytosol
Acetyl-CoA TCA cycle
Fig. 2.3 The reactions of glycolysis. Glucose, a six-carbon sugar, is first phosphorylated and then cleaved to form
two molecules of the three-carbon sugar glyceraldehyde-3-phosphate, which is subsequently converted into
pyruvate, accompanied by the formation of ATP and reduction of NAD + to NADH. Glycolysis makes two
molecules of ATP available for each molecule of glucose that passes through the pathway. If muscle glycogen is the
starting substrate, three ATP molecules are generated for each glucose unit passing down the pathway. Pyruvate
may enter the mitochondria and be converted into acetyl-CoA, or be reduced to form lactate in the cytosol.
Enzymes are set in small type; P i , inorganic phosphate; TCA, tricarboxylic acid.
muscle fibres is accompanied by hydrogen ions,
and this has the effect of making the buffer capacity
of the extracellular space available to handle
some of the hydrogen ions that would otherwise
cause the intracellular pH to fall to a point where