NETA Personal Trainer Practice Exam

What is the duration of energy provided by the Phosphagen System?

1. Up to 15 seconds

2. 10 seconds or less

3. 2-3 minutes

4. 3+ minutes

The correct answer is: 10 seconds or less

The Phosphagen System, also known as the ATP-PCr system, is predominant during short bursts of high-intensity activity. It primarily uses adenosine triphosphate (ATP) and phosphocreatine (PCr) stored within the muscles to fuel immediate energy needs. The duration of energy provided by this system is typically around 10 seconds or less, which is why this choice is accurate. During high-intensity exercises, the body quickly taps into these readily available energy stores for rapid bursts of activity, such as sprinting or heavy lifting. As these stores are depleted quickly, the energy system becomes insufficient for sustaining performance beyond that very short duration. Other energy systems, such as anaerobic glycolysis and aerobic metabolism, would then take over to provide energy for longer durations of exercise. The other options reflect durations that exceed the capacity of the Phosphagen System, which are more aligned with other energy systems that can sustain exercise beyond that immediate time frame.