What is the fate of any lactic acid produced in the muscles?

Answer 1

Once sufficient oxygen is restored, the lactic acid produced via anaerobic glycolysis can be utilized for energy or reconverted into glucose by the liver and other tissues (a process known as oxidation).

Answer 2

70% is converted to pyruvate and oxydised in the mitochondria,

20 in converted to glucose in liver,

10% converted to amino acids.

Answer 3

Look up "glycolysis" and then look at the diagram. Note that the lactic acid is reprocessed.