3.76 Monitoring the Intensity of Aerobic Exercise
Keeping your intensity level at the right place will help assure that you are getting the proper heart health benefits with your activity and help to you to avoid wearing out too quickly. There are two main ways that we monitor the intensity of aerobic exercise: heart rate monitoring and the “rating of perceived exertion” scale or RPE.
Monitoring your heart rate is very important when doing most exercises, especially aerobic exercises. You want to avoid very intense exercise, which will wear you out quickly. So if you see your heart rate is too high, you will know to reduce your pace.
The target heart rate recommended for you may vary depending on your condition and even based on the medications that you take, but there are specific definitions for “moderate intensity” and “vigorous intensity” exercise. Moderate intensity exercise gets your heart rate up to 50-70% of your maximum and vigorous intensity up to 70-80% of your maximum heart rate.
You can find your maximum heart rate simply by subtracting your age from 220. For example, a 50 year old person will have a maximum heart rate of 170 beats per minute. Once you know your maximum, multiply it by 0.5 to find 50% of your maximum, then multiple it by 0.7 to find 70% of your maximum. This will get you a target heart rate range for moderate intensity aerobic exercise. Do the same calculation, but use 0.7 and 0.8 to find your target heart rate for vigorous intensity exercise.
You can check your heart rate during exercise in multiple different ways, You can briefly pause your exercise and check your “radial pulse” on the front side of your wrist. Count the number of heartbeats in 6 seconds then multiple by 10 to find out how many beats per minute your heart is going.
A perhaps more accurate and convenient way, if you are technologically inclined, is to get a device that monitors heart rate for you during exercise, like an Apple Watch, FitBit or other device. These are easy to use, accurate and will store your heart rate and workout information for you as well as calculate the number of calories that you burned off.
If you are on medications that slow your heart rate down, such as “beta-blockers” like metoprolol or carvedilol or “calcium channel blockers” like diltiazem (Cardizem), then using heart rate during exercise will not be accurate. In these instances, you must use the “ratings of perceived exertion” or RPE that was mentioned earlier and aim for a 6-7 on that scale.
Note that the heart rate fluctuates quite a bit with strength training, so this is not how we gauge the intensity of a strength training routine.