How Do I Calculate my Maximum Heart Rate and Ideal Target Heart Rate?
Methods with High Potential for Error:
The Charts
We have all seen them hanging there on the gym wall. These charts use columns where you find your age and the correlating target heart rate zone. These charts can produce errors of plus or minus 20 beats per minute! The reason for this huge potential error is that they all use the generic formula of 220 -- AGE = maximum heart rate. This can be off by as much as +/- 30 beats per minute! In real life this means if you are 50 years old -- the charts will predict a maximum heart rate for you of 170 beats per minute. Meanwhile, your true maximum heart rate could be as low as 140 or as high as 200 beats per minute. That is the normal range of human maximum heart rates. From the charts you have no way of knowing if your maximum heart rate is lower or higher than 220 -- AGE. Remember that your maximum heart rate tells us nothing about your fitness level.
Exercise Machines and Heart Monitors
Unfortunately, these pieces of equipment use the same 220 -- Age estimation of maximum heart rate as the charts do. So any time you provide the equipment with your birth date or age, the onboard computer software is calculating 220 -- Age and all of the potential error that comes along with it.
Naturally, if you begin with incorrect maximum heart rate estimation you have no way of accurately calculating your training zone. You can do better than using the charts. Here's how:
Methods with Higher Accuracy:
An EKG (Electro Kardio Gram) Exercise Stress Test With a Physician
Most of the time these tests are done to screen people for safe participation in exercise. As a result, physicians are usually focused on looking for heart disorders such as arrhythmias and or changes in your EKG that suggest problems.
You need to advocate for yourself here and let your doctor know that you would like to know what your maximum heart rate is and what your optimal heart rate range is for exercise. During this test, you are hooked up to 12 electrode leads and put through a graded exercise test. "Graded" means that the work you are doing is increased every minute or so until either you get too tired to continue or your doctor stops the test. Since this test actually measures your individual heart rate response to exercise, your real maximum heart rate can be determined.
Keep in mind that most of the time these tests are stopped before actual maximum heart rate is reached. This is absolutely fine and normal (remember the description of what maximum heart rate feels like from above). However, since the test will not take you to your maximum heart rate, you and your doctor need to extrapolate what your actual maximum heart rate is. Some cardiologists will calculate a stopping point of the test of 85 percent of your age-predicted maximum heart rate. By now you should know that this is not necessarily going to be 85 percent of your maximum heart rate and is most likely not going to be your true maximum heart rate.
Once you and your doctor estimate your actual maximum heart rate, all that is left to calculate is 70 to 85 percent of that maximum to arrive at your target heart rate.
A Submaximal Exercise Test With an Exercise Physiologist
This test is done by an Exercise Physiologist (Look for a practitioner with a degree in the field and at least one certification from the American College of Sports Medicine). The physical part of the test is almost identical to the EKG exercise stress test discussed above. The primary differences are:
In the submaximal test with an exercise physiologist you will wear a heart monitor strap, not the 12 lead EKG electrodes. Therefore, this is not a diagnostic test. You must have clearance from your doctor permitting exercise program participation to do the submaximal test.
The submax test can be done on any piece of cardiovascular exercise equipment such as a treadmill, stationary bike, elliptical, stairclimber, rowing ergometer, etc. In this test you will wear a portable telemetric heart rate monitor during an eight to 15 minute graded exercise test. Every two minutes or so your exercise physiologist will increase the workload and record your heart rate. You will also be asked to rate the level of exertion you are feeling in your legs and breathing.
The exercise physiologist should be trained at determining 70 to 85 percent of your maximum heart rate based upon your exertion level, breathing pattern and speech pattern. These tests should always be stopped at 85 percent of maximum heart rate unless a physician is on the premises.
The take home message here is do not rely upon the charts or any other mathematical calculation to determine your maximum heart rate or your target heart rate zone. There is simply too much biological variation in heart rates to use anything other than a test which measures your individual response to exercise.
Stay tuned for my next article where I'll discuss how to use your target heart rate information to design the most effective calorie and fat burning exercise program for you.