Which energy system is primarily engaged during prolonged, moderate-intensity activity such as a slow jog?

Which energy system is primarily engaged during prolonged, moderate-intensity activity such as a slow jog?

• A. ATP-CP (Phosphagen) system
• B. Lactic acid system
• C. Oxidative phosphorylation system
• D. Anaerobic glycolysis

Answer: (C)

During prolonged, moderate-intensity activity, the body relies primarily on the oxidative phosphorylation system. This aerobic pathway uses oxygen to completely break down carbohydrates and fats to produce ATP, supporting sustained energy production for extended periods. Because it depends on oxygen and mitochondria, its rate of ATP production is slower than the quick-energy systems, but it has a much larger capacity, making it ideal for activities like a slow jog that continue for many minutes or longer. The other systems provide energy for shorter, higher-intensity efforts: immediate energy from the phosphagen system lasts only a few seconds, and anaerobic glycolysis supplies energy for higher intensity efforts lasting roughly from tens of seconds up to a couple minutes but does so without relying primarily on oxygen.

During prolonged, moderate-intensity activity, the body relies primarily on the oxidative phosphorylation system. This aerobic pathway uses oxygen to completely break down carbohydrates and fats to produce ATP, supporting sustained energy production for extended periods. Because it depends on oxygen and mitochondria, its rate of ATP production is slower than the quick-energy systems, but it has a much larger capacity, making it ideal for activities like a slow jog that continue for many minutes or longer. The other systems provide energy for shorter, higher-intensity efforts: immediate energy from the phosphagen system lasts only a few seconds, and anaerobic glycolysis supplies energy for higher intensity efforts lasting roughly from tens of seconds up to a couple minutes but does so without relying primarily on oxygen.