Why do you feel warm when you work out?

• A. Because your body absorbs heat directly from the surrounding air.
• B. Because your sweat cools your body by increasing your internal temperature.
• C. Because your muscles convert chemical energy from food into thermal energy during exercise.
• D. Because your blood releases energy in the form of light.

Answer: (C)

Verified step by step guidance

1. Understand that when you work out, your muscles require energy to contract and perform work.
2. Recognize that this energy comes from the chemical energy stored in the food you have consumed, primarily in molecules like glucose.
3. Know that during exercise, your muscles convert this chemical energy into mechanical energy to move, but not all energy is perfectly converted; some is lost as thermal energy (heat).
4. This thermal energy raises your body temperature, which is why you feel warm during physical activity.
5. Therefore, the warmth you feel is due to the conversion of chemical energy into heat by your muscles, not because of heat absorbed from the air, sweat increasing temperature, or light energy from blood.