Intense muscle activity results in an oxygen debt, which is the amount of oxygen needed to compensate for ATP produced without oxygen during muscle contraction. What are the processes that require oxygen to restore ATP and creatine phosphate levels, convert lactic acid to pyruvic acid, and convert lactic acid into glucose or glycogen in the liver?
1) Restoring ATP and creatine phosphate levels
2) Converting lactic acid to pyruvic acid
3) Converting lactic acid into glucose or glycogen in the liver
4) All of the above