How to Use a Heart Rate Monitor

Another easy but less precise option for finding FTHR is to pay close attention to how you feel when running and rate your effort on a 1 to 10 scale, with 1 being very easy and 10 being all-out. When you say to yourself, "This feels like a 7," look at your heart rate monitor. You are close to FTHR.

Once you find your FTHR, determine your training zones—the heart rate ranges that will help you reach specific fitness goals—by using this table. Be aware that your FTHR and zones vary by sport. The following is how you find your zones for running. The more times you repeat your FTHR with the above methods, the more accurate your zone numbers will become.

Zone Equation To Determine Zones Zone Purpose
Zone 1 <0.86 x FTHR Active recovery
Zone 2 0.86-0.91 x FTHR Aerobic endurance
Zone 3 0.92-0.96 x FTHR Muscular endurance
Zone 4 0.97-1.02 x FTHR Anaerobic endurance
Zone 5 >1.02 x FTHR Aerobic capacity

More: Calculate Your Training Heart Rate Zone

How does a heart rate monitor work—and do I have to wear a chest strap?

A heart rate monitor works by detecting the electrical activity your heart creates when it beats, much the same way a cardiologist uses an electrocardiogram to measure your heart's electrical impulses. As you work harder, the heart beats faster and your nervous system directs more closely spaced electrical firings.

The most accurate way to capture this data is to wear a sensor on your chest, close to your heart. Other methods, such as the common infrared sensor on the end of your finger, are more likely to produce highly variable and less accurate readings. Heart rate monitors use a wireless device, worn on the chest strap, which transmits heart rate data to your wrist receiver, where it is deciphered and displayed. Sports bras and athletic apparel made by Numetrex (numetrex.com) are designed to hold this device, making a chest strap unnecessary.

As with most tech devices, you can find all sorts of bells and whistles in a heart rate monitor. One handy feature is a calorie counter. Using your body weight, the type of exercise you perform and your intensity, it can correctly estimate how many calories you burn in a workout—good information if you are watching your waistline or want to know how many calories you need for recovery.

Other possible add-ons are speed and distance measurements—using GPS or an accelerometer, on-wrist graphs and memory recall by zones. Expect to pay more every time you add on a feature. None of these add-ons changes the basic function of the monitor, which is to measure your precise heart rate at any given moment during exercise.

I'm a triathlete and already use a lot of electronics to monitor my workouts. Is there something that combines all my needs in one interface?

There are lots of products on the market—made by companies like Polar (polarusa.com)—that combine heart rate monitoring with other features. While running, you can use a speed-and-distance device such as an accelerometer or sport GPS to capture and simultaneously display pace, distance covered, altitude, hill grades and heart rate. On the bike, a power meter shows both power and heart rate along with normally displayed handlebar computer data such as speed, time, distance and cadence.

Combining heart rate with pace or power adds a great deal of value to the data you gather. Pace and power are output measures when running and riding. Heart rate is a measure of input. When you compare output with input, you know economy. You're used to doing this with your car when you determine its miles (output) per gallon (input).

More: Understanding Your Heart Rate and Exercise

To determine your bike economy using a power meter, divide the workout average watts by the average heart rate. For the run, divide average speed by average heart rate. If you know your exercise economy and see it improve with more training (more power or faster pace per heart beat), then you have a sure sign you're becoming more fit.

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