What is the first source for supplying additional ATP when exercise begins

Question

Quizplus · Accepted Answer

Creatine phosphate is the first source for supplying additional ATP when exercise begins because it can rapidly donate its phosphate group to ADP to instantly form ATP. This process is anaerobic and occurs within the muscle cells themselves. The energy from creatine phosphate can sustain muscle contractions for a brief period, typically lasting for up to 10 seconds. After that, glycolysis becomes the main source of ATP.

What Is the First Source for Supplying Additional ATP When