As long as you are reading this article the answer to that question is "Yes." The real question is, "Do you know what your heart rate is while you train?" Even more importantly, do you know what your heart rate should be during any given workout? Monitoring your heart rate is an important component of successful endurance training, and can help you train better and race faster in the long run - pun intended!

Let's begin first with a basic exercise physiology lesson. Heart rate is simply the speed at which your heart contracts, measured in beats per minute (BPM). The heart rate response to exercise is an effective estimate of exercise intensity in most situations. Keep in mind that heart rate can be significantly affected by temperature, caffeine use, stress, illness and race anxiety.

Exercising at the proper intensity can speed your improvement as an endurance athlete. Working out too hard and too often can lead to overtraining, while training too easy will lead to underperformance. Since time is a commodity for most runners, efficient training sessions performed at the right intensity give you the biggest bang for your buck - or better put, a faster time in your next race.

Using a heart rate monitor, now available for around $50 for a basic model, is the first step. From this point forward, I will assume that you are using a heart rate monitor. There are many models out there from a basic one, all the way up to computer downloadable monitors that will keep track of almost everything you can imagine, including temperature and altitude. Athletes who have been using heart rate monitors for a long time often develop an uncanny ability to estimate their heart rate within a couple of beats per minute simply by monitoring their perceived effort. With practice, you can develop your own internal heart rate monitor!

Successful use of heart rate to monitor your training comes in the form of establishing proper ranges for different runs. Examples include: Recovery, Overdistance, Endurance, Tempo/Lactate Threshold (LT), and VO2 Max. These zones are not necessarily magic, and sometimes include some overlap in heart rate ranges. These ranges are important, though, and are based off of each individual's response to training, not simply a maximum heart rate.

You can base training recommendations off of the blood lactate and heart rate response to exercise. This requires a lactate profile test where heart rate and blood lactate concentrations are measured at progressively faster four-minute stages. The lactate threshold is the heart rate and pace at the point where blood lactate levels begin to increase significantly.

This heart rate and pace is close to what a well-trained runner can sustain during races of about 10 miles to a half marathon. For most runners, this heart rate is about 10 beats per minute lower than their average heart rate during a 10K race. Once the lactate threshold pace and heart rates are determined, training zones can be assigned based on your blood lactate response.

Most runners should spend a majority of their time in Overdistance and Endurance intensities, with one or two workouts at the Tempo/Lactate Threshold effort each week. Once you have a strong base and are beginning to peak for a race, cut back your total volume of training, and begin adding a weekly VO2 max session. During higher intensity workouts, your heart rate may drift upwards during the progress of a workout. Don't worry about that, but do try to monitor your effort during these sessions. These harder days shouldn't leave you completely wasted - that's what race day is for!

Many athletes tend to train at an intensity that's too high during their base and endurance training, and at too low of an intensity during Tempo/LT and VO2 Max sessions. This "regression toward the mean" results in decreased motivation and poor race performances. By expanding your range of training intensities and using your heart rate monitor effectively, you will become a faster and more time efficient athlete!

Determine Your Training Zones

Recovery Zone
This zone includes your warm-up, cool-down and easy workouts. Train at a level less than 40 beats per minute below your LT heart rate for 20-40 minutes.

Overdistance Zone
This zone includes your base training and your long runs to improve the body's ability to use fat as a fuel source. Train at a level 20 to 40 beats per minte below your LT heart rate for 60- 180 minutes.

Endurance Zone
This zone includes workouts to improve your aerobic capacity and muscular endurance. Train at 10-25 BPM below your LT heart rate for 30-60 minutes.

Tempo/LT Zone
This zone includes workouts to improve lactate tolerance and race-pace economy. To determine this zone, take your LT heart rate +/- 3-8 BPM. Duration: 15-30 minutes of intervals or sustained effort.

VO2 Max
This zone includes workouts to increase the amount of blood pumped by the heart and to increase leg speed. Train at 90-95% of YOUR max HR (Don't estimate - use the highest heart rate you've seen while running). Duration: Shorter intervals totaling 8-15 minutes.

Estimated lactate threshold heart rate =
Average 1/2 marathon HR - 5 BPM
Average 10K HR - 8 to 12 BPM
Average 5K HR - 15 BPM

Use the following equation to estimate your lactate threshold heart rate. You can also determine your lactate threshold heart rate by performing a lactate profile test at a physiology lab.

Neal Henderson, MS CSCS won the 2001 Snow Mountain Ranch Trail Marathon and is the Coordinator of Sport Science at the Boulder Center for Sports Medicine.