Understand Your Exercising Heart Rate

You can use this chart to find your optimal exercise heart rates by using your resting heart rate and your age. This chart is based on the Karvonen Formula.

Maximum Heart Rate

100% is the level of your heart rate at its maximum intensity. It is your survival heart rate. For example; if there was a fire and you had to gather your belongings, flee a building, and get out to your car, by the time you reached your car, your pounding heart would probably have reached its maximum heart rate, its 100%. It is your "fight or flight" heart rate. You won't die at that heart rate, but, you only have 9 seconds of energy at that intensity. The fuel our bodies uses during emergencies such as this is glucose or "sugar" (carbohydrate), not body fat. Our bodies store a small amount of "sugar" in our muscles (called glycogen) and there is glucose traveling around in our blood. Glucose is the only fuel our brain uses, so when we use up this blood sugar during a high impact aerobics class, we feel fatigued, hungry, and sometimes dizzy during or afterwards.
We should never exercise at that maximum intensity (100% of your maximum heart rate equals 220 minus Your Age ). In addition to exhausting us for many hours afterward and increasing our appetite, high intensity activity can easily cause an injury, which stops our exercise program temporarily or even permanently, and besides, we're not even burning body fat.

Sports Heart Rate
80% is our sports heart rate. We get to this high an intensity for a few minutes at a time playing tennis or running bases in a softball game. Athletes use short spurts of energy at 80% in a football game or running the 50 yard dash. However, most "no pain, no gain" aerobics exercise classes have you exercise at 80% heart rates. This is wrong and dangerous! 80% is very close to 100% and much too intense for a sustained exercise session, especially for some one who is over 50, deconditioned or overfat. The more recent studies show that at 80% intensities the injury rate is very high and not worth the risk. In other words the wrong exercise might be worse than no exercise. Besides, the high intensity of the exercise causes the body to think it's in a "fight or flight" situation so the fuel the body uses is primarily glucose not fat.

Optimal Heart Rate - for cardiovascular fitness and burning body fat
60% is our optimal heart rate during exercise. The studies that looked at exercise intensities at 80% compared these rigorous activities with more moderate exercise, like walking, stationary biking, and Walkaerobics, which get heart rates up to 60%. They found that the cardiovascular improvements were similar in 60% and 80%, but the injury rate was substantially lower at 60%. They also found that the moderate intensities burned more body fat as fuel.

Most enlightened exercise specialists now agree with the ACSM that the optimal heart rates during exercise should reach an intensity of 60% or less.