What is the first means by which ATP is produced at the onset of contractile activity

Question

Quizplus · Accepted Answer

Creatine phosphate is stored in muscles and can be rapidly broken down to transfer a phosphate group to ADP, creating ATP for immediate energy needs at the start of contractile activity. This is known as the phosphagen system and is the first means by which ATP is produced. Glycolysis and oxidative phosphorylation also contribute to ATP production but take longer to start up. The degradation of myoglobin does not directly produce ATP.

What Is the First Means by Which ATP Is Produced