ACE Personal Trainer Practice Exam

What does creatine phosphate do in muscle cells?

1. It breaks down carbohydrates for energy

2. It serves as a storage form of high energy phosphate

3. It transports oxygen to muscle tissue

4. It helps maintain muscle hydration

The correct answer is: It serves as a storage form of high energy phosphate

Creatine phosphate plays a crucial role in the energy metabolism of muscle cells. It serves as a rapid source of high-energy phosphate that is used to regenerate ATP (adenosine triphosphate), the primary energy carrier in cells. When muscles contract during short bursts of intense activity, they rapidly consume ATP. Creatine phosphate donates its phosphate group to ADP (adenosine diphosphate) to reform ATP, allowing the muscles to sustain short-duration, high-intensity efforts. While carbohydrates are indeed broken down for energy, that process is distinct from the specific function of creatine phosphate in energy storage and ATP regeneration. Additionally, creatine phosphate does not transport oxygen; that role is served by hemoglobin in red blood cells and myoglobin in muscle tissues. Muscle hydration is maintained through fluids and electrolytes, not directly by creatine phosphate. Therefore, its primary function as a storage form of high-energy phosphate is what makes this answer correct.