How your body responds to aerobic exercise

During aerobic activity, you repeatedly move large muscles in your arms, legs and hips. You'll notice your body's responses quickly.

You'll breathe faster and more deeply. This maximizes the amount of oxygen in your blood. Your heart will beat faster, which increases blood flow to your muscles and back to your lungs.

Your small blood vessels (capillaries) will widen to deliver more oxygen to your muscles and carry away waste products, such as carbon dioxide and lactic acid.

Your body will even release endorphins, natural painkillers that promote an increased sense of well-being.