Are You Working Out Efficiently?

Maximize your workout with a heart-rate monitor.

According to Prevention Magazine, knowing the range of your target heart rate means knowing how to either intensify your workout or maintain a pace that is comfortable but still effective.

"Exercise is like medication," says the magazine's senior fitness editor, Michele Stanton, on The Early Show "You can get an overdose and an under-dose. And by knowing your target heart-rate zone, that can help you get the right dose. (With) a heart-rate monitor, (it) is easy to calculate that."

Here is how you can determine what your target heart-rate zone is:

"A target heart-rate is 60-90 percent of maximum heart rate," notes Stanton. Calculating the target heart-rate zone for CBS News John Roberts who is 47, she explains how to do the math.

First, subtract Roberts' age from 220, which equals 173. Then multiply 173 by .6 to get the lower number in the range: which is 104. Then multiply 173 by .9, to get the higher number in the range: which is 156.

The higher the intensity, the more calories you'll burn. So in this case, Roberts will want to keep his heart rate between 104 and 156 to get a maximum fat burning workout.

"If you're just starting out," Stanton says, "stay toward the lower end. If you've been exercising for a while, bump up the intensity. Try going to the higher end."

Here are few of the heart-rate monitors featured in the August edition of the magazine:

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