Why does my heart beat faster when I run?
Heart's Speedy Delivery
Why does my heart beat faster when I run?
You're sprinting across the field, feet pounding, and suddenly you notice: your heart is going wild in your chest. Thump-thump-thump-thump, way faster than it was a minute ago when you were standing still. What's it doing in there?
Your heart is a pump — its whole job is to push blood through your body, delivering oxygen to every muscle, organ, and cell. When you're sitting on the couch, your muscles don't need much oxygen, so your heart can take it easy. Beat... beat... beat... about once per second.
