The most accurate measure of your Maximum Heart Rate (MHR) is to have a stress test performed by a trained professional. Some fitness facilities can do this testing but your best choice would be to consult your doctor about taking a stress test under medical supervision.
This page will calculate your approximate MHR from several different formulas based on gender, age, weight and if known your Resting Heart Rate (RHR). The first set of calculations use the basic formula for MHR. Take the Fetal Heart Rate (FHR), which is 220 for men and 226 for women, and subtract your age:
MHR = FHR - ageThen you use standard percentage calculations to get the 60%, 70% and 80% values.
If you know your RHR the Karvonen Method is more accurate for figuring Target Heart Rate (THR). It uses the same basic MHR calculation but does a better job of estimating an individual's THRs by using the RHR to adjust the numbers.
80% THR = (MHR - RHR) * 0.8 + RHRTo discover your RHR you should take your pulse first thing in the morning before getting out of bed. Repeat this for five days in a row and average the five values to get a base value for your RHR.
The third calculation uses a formula developed by Dr. Dan Heil after studying 1500 walkers at the University of Massachusetts. This formula calculates MHR using the additional factor of body weight. For men only there is a constant value of 4.5 added to the final result. The formula looks like this for men. Leave off the addition of 4.5 for women:
211.415 - (0.5 * age) - (0.05 * weight in lbs) + 4.5Every individual is different. The results of all these MHR calculations are approximate. The standard error for the basic formula can be as high as 12 to 24 beats per minute. Again, the best measure of your MHR is to have a supervised stress test.
Exercising while your heart rate is between 60% and 80% of your MHR is a good aerobic workout. It's recommended for building up a solid fitness base and burns fat that your body has stored rather than carbohydrates that you've recently consumed. A good aerobic workout between 60% and 80% of your MHR should also leave you refreshed and invigorated instead of tired and worn out.
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