Rating of perceived exertion (RPE) can help you measure how hard your body is working when you exercise. To do this, you monitor yourself as you exercise. For example, you think about how tired you are, how hard it is to breathe, and how hard it is to do the activity.

An RPE is usually used as part of a cardiac rehab program. Your cardiac rehab team will teach you how to use RPE. Then you may be able to use it when you exercise on your own.