Why does my heart hurt when i run?

Careful: If you are out of shape and just getting into running, your heart and blood vessels are not accustomed to your sudden increase in activity. Start more slowly and gradually build up to more activity. It's generally a good idea to go have a full physical exam before starting a running program if you haven't been running before.

Stress test: If your "heart hurts", you need a stress test to determine if you have blocked arteries in your heart. At your age, it's more likely that running is causing muscular chest wall pain or acid reflux (in your digestive tract).