What are the primary energy systems used during physical activity?

The primary energy systems used during physical activity include the phosphagen system, anaerobic glycolysis, and the aerobic system.

The phosphagen system is the body’s immediate source of energy, utilizing stored ATP and creatine phosphate for quick, high-intensity efforts lasting about 10 seconds or less. It is critical for activities like sprinting or heavy lifting, where rapid bursts of energy are needed.

Anaerobic glycolysis kicks in for slightly longer durations of high-intensity activity, providing energy for about 30 seconds to 3 minutes. This system breaks down carbohydrates without the need for oxygen, producing ATP rapidly but also creating lactic acid as a byproduct, which can lead to fatigue.

The aerobic system is the primary energy system for prolonged, lower-intensity activities, such as jogging or cycling. It relies on oxygen to break down carbohydrates, fats, and proteins to produce ATP, allowing for sustained energy supply over long periods.

In combination, these systems give the body a well-rounded capability to respond to various intensities of physical activity, making option B the most accurate representation of the primary energy systems used during exercise.