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with less chance of injury. As you get more fit, you may want to do some of

your training in the middle and upper end of your zone. In Chapter 7, we offer

examples of ways to mix up your training.

So how do you know what your maximum heart rate is? Well, we don’t recom-

mend running as hard as you can until you keel over, and then counting your

heartbeats for one minute. A safer and more accurate way is to have your

max measured by a professional such as a physician or exercise specialist.

(See Chapter 2 for details on exercise testing.) You can also use a number of

mathematical formulas to estimate your max.

112 Part III: Getting to the Heart of the Matter

The Karvonen method for target heart rate

One of the problems with the standard formula

for finding your target heart rate is that it takes

only your age into consideration. This is a valid

consideration because your recommended

maximum heart rate declines as you age.

However, the following formula, called the

Karvonen method, is somewhat more accurate

because it also factors in your resting heart

rate,the number of times your heart beats when

you’re sitting still. Typically, as you become

more fit, your heart rate drops.

The Karvonen method requires a bit more math,

but don’t let that intimidate you. In this example,

we use the case of a 40-year-old man who has

a resting heart rate of 60 beats per minute and

wants to work at between 50 percent and 85

percent of his maximum heart rate. Grab your

calculator and follow these step-by-step

instructions:

1. Subtract your age from 220.
   Using our example, 220 – 40 = 180.

This is our subject’s estimated maximum.

2. Subtract your resting heart rate from your
   estimated maximum.

180 – 60 = 120.

3. Multiply the number you arrived at in Step
   2 by 50 percent. Then add your resting heart
   rate back in.
   120 ×0.50 = 60

60 + 60 = 120

120 is the low end of the man’s target zone.

4. Multiply the Step 2 result by 85 percent.
   Then add your resting heart rate back in.
   120 ×0.85 = 102

102 + 60 = 162

162 is the high end of the man’s target zone.

Okay, now that you feel like you’ve earned your

Ph.D. in calculus, you can compare the results

of this formula with those of the traditional for-

mula. Using the age-related formula, this 40-

year-old’s target zone is 90 to 153 beats. But

when you factor in his resting heart rate, this

allows him to work up to 162 beats per minute.

And he knows that if he drops below 102 beats,

he probably needs to pick up the pace.