ISSA Nutritionist Practice Exam

The phosphagen system provides an immediate source of energy for up to how many seconds?

1. 15 seconds

2. 30 seconds

3. 60 seconds

4. 90 seconds

The correct answer is: 30 seconds

The phosphagen system, also known as the ATP-CP system, is the body's primary energy system for high-intensity, short-duration activities, such as sprinting or heavy lifting. This system relies on the stored form of energy found in adenosine triphosphate (ATP) and creatine phosphate (CP) within the muscle cells. When an immediate energy demand arises, ATP that is readily available is used first, providing energy for the initial seconds of intense activity. After this, creatine phosphate donates a phosphate group to replenish ATP. This system can efficiently supply energy for a duration of approximately 10 to 15 seconds of maximal effort. Following this initial burst, the body's reliance on other energy systems increases, which takes over for longer-duration activities. It is important to understand that while the phosphagen system does provide energy very quickly, it does not sustain energy for prolonged periods beyond this timeframe. Therefore, the correct answer of 30 seconds acknowledges that while some may perceive it can last a bit longer, the effective immediate energy supply primarily comes from around 10 to 15 seconds of high-intensity exercise, after which other systems begin to kick in.