Question: How important is taking your heart rate while you are exercising to get a good exercise effect?
Answer: There are four basic guidelines for developing aerobic fitness: choosing the proper mode of exercise; working at the correct intensity; going the optimum frequency each week; and exercising long enough to make a change. Taking your heart rate during exercise has long been the primary means of determining intensity.
However, there are problems with using heart rate to determine intensity. First, the heart-rate guidelines are quite broad. The American College of Sports Medicine recommends an intensity between 60 percent and 90 percent of maximum heart rate. To figure your maximum heart rate, subtract your age from 220. For example, a 40-year-old person would have a maximum predicted heart rate of 180. The training range for that person would be between 108 (180 x .6) and 162 (180 x .9), quite a difference. To make it even more confusing, a person with a low initial level of fitness would use an even lower percentage.
The second problem is that maximum heart rate, as mentioned, is predicted by subtracting your age from 220. But there is a wide variability between actual versus predicted maximum heart rate. Only two-thirds of the population is within 12 beats of the predicted. I have seen people who exercise at a heart rate that is higher than their predicted maximum heart rate and others whose maximum rate is below the recommended training rate.
Another problem relates to the difficulty of measuring heart rate accurately. Many people are unable to count the pulse very well while they are exercising, and if they stop to count, the pulse goes down so rapidly that it is difficult to get a realistic number. Because of these problems, I teach people to count for 10 and multiply by six (or 15 seconds and multiply by four ) to get the heart rate during the exercise bout. When done properly, this is a pretty good estimation of actual exercise heart rate.
Of course, using heart rate in a professional setting, such as a cardiac rehabilitation center or hospital fitness center is much easier and more meaningful. In these centers, maximum heart rate can be actually measured during a graded exercise stress test and the fitness level that was measured in the test can be used to determine the most effective heart rate. Then, monitors can be work by the person during a few exercise sessions to be sure that he or she works at the proper intensity.
So how do you measure intensity if you don't have a fitness facility to get better information? First, be sure to check with your personal physician if you have any questions about your health of if you simply want to feel safer changing your activity level. If you haven't exercised for a long while or if you are a little overweight, you don't need to worry about the intensity — you should exercise easily and slowly for only five to 10 minutes a time for a week or so just to see how your body will respond.
After several weeks, when you are sure that your body is responding well to the exercise and you have worked up to 10 to 15 minutes a workout, calculating a training heart rate could be valuable in terms of feedback. Begin with 60 percent to 70 percent of your predicted maximum heart rate. Calculate your pulse after exercising easily for three or four minutes. This calculated pulse rate will give you a rough idea if you are in the heart-rate range for effective exercise.
If your heart rate during exercise is quite a bit below the calculated heart rate for training, increase your intensity a little and check again. Just remember that your maximum heart rate may be different from the one you calculated, so listen to your body and exercise at a level that feels comfortable to your.
I used to check my heart rate quite often, and my calculated heart rate was similar to the heart rate that felt comfortable for my workout. Now, I seldom check my heart rate; but some days I can do more than others. If I am jogging and feel a little too tired, I slow down and walk for a minute or two. The key? Listen to your body and you will seldom go wrong.
Garth Fisher is the former director of the Human Performance Research Center at Brigham Young University.