gen-explain-the-energy-systems-of-exercise-as-you-would-to-a-cap-3a89

Explain the energy systems of exercise as you would to a capable student, in 3-4 sentences.

# Energy Systems of Exercise Your body uses three energy systems to fuel movement, depending on the intensity and duration of exercise. The **ATP-PC system** provides immediate energy for explosive efforts lasting up to 10 seconds (like a sprint start), while the **glycolytic system** kicks in for high-intensity activities lasting 30 seconds to 2 minutes (like a 400m run), producing energy quickly but creating lactic acid as a byproduct. For longer, sustained efforts, your **aerobic system** uses oxygen to break down carbohydrates and fats efficiently, powering activities like distance running or cycling. These systems don't work in isolation—they overlap and contribute simultaneously, with their relative contributions shifting based on how hard and how long you're exercising.