Module 1-8: Understand Your Heart Using Heart Rate Monitor

Until you learn what the numbers displayed on your wrist mean, the heart rate monitor is just a "gee whiz" toy. To give the numbers meaning, you need a reference point, a heart rate unique to you at a given level of intensity. Depending on the brand and model of your heart rate monitor, some will take you through a simple workout to determine this number, but this isn't always the most accurate method to use. It's better to calculate this on your own.

First, find your Functional Threshold Heart Rate (FTHR). There are a few ways to find your FTHR. Wear your heart rate monitor and warm up, then run hard for 30 minutes as if you were in a race. Or you may actually participate in a race that will take you about 60 minutes to complete. Your average heart rate for either run, if you were going hard, is a good predictor of your FTHR.

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.

Active Recovery Zone
Multiply your FTHR by 0.86; this is your active recovery rate, so any time your heart rate monitor reads below this number, you are in an Active Recovery state and haven't reached the endurance level.

Aerobic Endurance Zone
Multiply your FTHR by 0.91. Any time your heart rate monitor reads between your active recovery rate and this number, you are within your Aerobic Endurance state and burning a significant number of calories per hour.

Muscular Endurance Zone
Multiply your FTHR by 0.96. Any time your heart rate monitor reads between your aerobic endurance rate and this number, you are within your Muscular Endurance state and burning a moderate amount of calories per hour.

Anaerobic Endurance Zone
Multiply your FTHR by 1.02. Any time your heart rate monitor reads between your Muscular Endurance Rate and this number, you are within your Anaerobic Endurance rate.

Aerobic Capacity Zone
Anything greater than your maximum Anaerobic Endurance rate is your Aerobic Capacity, which may be your maximum calorie-burning potential and highest performance/endurance level.

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.