What happens to the body during the aerobic phase of a workout?

During aerobic exercise your body must supply fuel for working muscles. To do this your body performs a series of chemical reactions that breakdown primarily carbohydrates and fat into a usable form of energy (glucose). Think of carbohydrates and fat as fuel for your body like gasoline is the necessary fuel for your car. In addition your body’s heart rate and breathing rates increase as well as slight increase in temperature. The harder and faster you work the more energy is needed and subsequently the faster your heart beats to supply oxygen to working muscles.

During the aerobic phase, you rev up, keep your body moving, and get your heart pumping. Your muscles will require more oxygen during this phase. Your heart beats faster and your lungs breathe deeper to deliver oxygen through your small blood vessels to muscles.

If you are starting a new exercise program, you may not be able to sustain aerobic activity for very long. That’s okay. Try 5–10 minutes at first, and gradually increase the aerobic phase. An easy workout is better than none at all. Sometimes once you get going, you will feel better and will go the whole way. Eventually, you will be able to go the full 20–30 minutes. Just listen to your body and slow down when you need to.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.