Over the years, I've had many a client who started on my fitness program who stated they were working out before and getting nowhere. After a quick observation of their program, I realize they are not working out hard enough. They usually don't know at what intensity they should be exercising.
Target Heart Rate
According to the American College of Sports Medicine, to improve your cardiorespiratory fitness you must workout between 55% to 90% of maximum heart rate. You want to keep your heart rate between 55% to the high end of 90%. If you are new to working out or have cardiac conditions, keep your intensity on the low end of the scale between 55%-70%. As your cardiorespiratory system becomes more fit, you can increase your target rate to 75% to 90% MHR. If you don't know how to take your pulse see the picture to the left. Make sure you take your pulse with two fingers and not your thumb. When taking the pulse on the wrist make sure you place your fingers on your thumb side of your arm (Radial pulse). Click the link, to follow the Karvonen target heart formula. http://www.wikihow.com/Calculate-Your-Target-Heart-Rate
Rate of Perceived Exertion
People on medication that slows down the heart rate cannot use the target heart rate method, so another intensity measurement is needed and it is called rate of perceived exertion or RPE. It is a scale based on your overall feeling as you exercise. Read the following chart below, this is from the Cleveland Clinic:
The RPE scale is used to measure the intensity of your exercise. The RPE scale runs from 0 – 10. The numbers below relate to phrases used to rate how easy or difficult you find an activity. For example, 0 (nothing at all) would be how you feel when sitting in a chair; 10 (very, very heavy) is how you feel at the end of an exercise stress test or after a very difficult activity.