Heart Rate Monitors

By monitoring heart rate, the simple observation that the harder we exercise, the faster our heart beats is put to good use. Professional athletes and amateurs alike have for decades been relying on the information provided by their heart rate monitor for the following reasons:

A heart rate monitor is like a rev counter, giving a precise measurement of exercise intensity.

Training at your own ideal pace is made possible with a heart rate monitor.

Direct measurement of heart rate during exercise is the most accurate way to gauge performance.
Progress can be monitored and measured, increasing motivation.

It maximizes the benefits of exercise in a limited amount of time.

It introduces objective observation. Are you on the right track? Are you improving?

It is a tool for regulating frequency and intensity of workouts.

Because of the immediate feedback it provides, heart rate monitoring is an ideal training partner.
How does it work?

When you start training, your heart rate increases rapidly in proportion to the intensity of the training. In Polar Heart Rate Monitors, the transmitter belt detects the electrocardiogram (ECG – the electric signal originating from your heart) and sends an electromagnetic signal to the Polar wrist receiver where heart rate information appears.

The heart moves blood from the lungs (where the blood picks up oxygen) to the muscles (which burn the oxygen as fuel) and back to the lungs again. The harder the training, the more fuel the muscles need and the harder the heart has to work to pump oxygen-rich blood to the muscles.

As you get fitter, your heart is able to pump more blood with every beat. As a result, your heart doesn’t have to beat as often to get the needed oxygen to your muscles, decreasing resting heart rate and exercise heart rate on all exertion levels

Exercise zones are ranges between the lower and upper heart rate limits expressed as beats per minute (bpm) or as percentages of your maximum heart rate (HRmax). HRmax is the highest number of heartbeats per minute during maximum physical exertion.

Heart Rate Target Zones

Exercise can be divided into three different intensity zones. Each of these intensity levels corresponds to various health and fitness improving mechanisms in your body.

Light Intensity Zone

When your heart beats at 60-70% of your HRmax (HRmax %), you are in the Light Intensity Zone. Whether you have just started working out or you exercise fairly regularly, much of your workout will be in this zone. Fat is the body’s main source of energy at this level of intensity; therefore this zone is also good for weight control. This intensity still feels fairly easy for most people and provides, for example, the following benefits:

Helps in weight control

Improves endurance

Improves aerobic fitness

Moderate Intensity Zone

Push on to 70-80% of your HRmax, and you are in the Moderate Intensity Zone. This is especially good for people who are exercising regularly. For most people, this is often the fastest pace they can maintain and still remain comfortable and free of pain. Exercising in this zone is particularly effective for improving aerobic (i.e. cardiovascular) fitness. If you are out of shape, your muscles will use carbohydrates for fuel when you are exercising in this zone. As you get fitter, your body starts using a higher and higher percentage of fat for fuel, thus preserving its limited stores of muscle carbohydrate. Exercising in the moderate intensity zone results in some additional benefits:

Improves aerobic fitness

Improves endurance

Helps in weight control

Accustoms your body to exercising at a faster pace

Begins to raise the speed you can maintain without building up lactic acid

Hard Intensity Zone

At 80-90% of your HRmax, you have moved into the Hard Intensity Zone. Exercise in the hard intensity zone definitely feels “hard”. You will find yourself breathing heavily, having tired muscles and feeling fatigued. This intensity is recommended occasionally for fit people. Exercising in this zone is intensive, so it provides some unique benefits:

Increases muscles’ tolerance to lactic acid

Improves hard, short effort ability

When you exercise in the correct intensity zones, it guarantees your enjoyment in your favorite sports. Alternate between intensity zones to improve your fitness and get variation in your exercise. Remember that the lower the intensity the longer you can comfortably exercise in it. Exercise in the higher intensity for shorter periods.

Note: Polar target heart rate intensity definition is modified from international exercise science authorities’ recommendations in which light intensity can reach lower than 60% of HRmax.

In addition to exercise intensity and your level of aerobic fitness, the following factors affect your heart rate during outdoor training :

Activity. Heart rate can change across activities, due to different muscle mass involved, level of experience and technical proficiency. Running typically elicits the highest maximum heart rate during a stress test, whereas cycling and paddling maximum heart rates can be 10-15 beats lower during a similar test. This means that you may need to adjust your training heart rate intensities by 5-10 beats for activities other than running.

Heat and Humidity. Temperature and humidity will influence your heart rate. As the environment gets warmer and more humid, heart rate will gradually increase throughout your activity, even if your pace doesn’t change. This is due to your “air-conditioning” and level of hydration. You produce a lot of energy in the form of heat when you move and this heat needs to be dissipated, typically via sweating. Humidity reduces the effectiveness of sweating, resulting in an increase in body temperature, and thus an increase in heart rate. Even if the humidity is low, heart rate will still be elevated, due the extra work the heart must do to help cool your body. It’s not uncommon for heart rates to be 5-10 beats above normal ranges in these conditions. Use your heart rate combined with perceived exertion and subjective feeling to set an appropriate pace.

Hydration. Failing to stay hydrated can result in an increase in heart rate, as your blood volume decreases and your body runs low on the fluids needed to maintain body temperature. Dehydration can occur in cold as well as hot environments. If you notice your heart rate increasing with no change in pace or other variables, then increase your fluid intake.

Altitude. The lower air pressure at altitude means there is less pressure to drive oxygen into your lungs. Less pressure means your heart has to work harder to deliver enough oxygen to your working muscles. The result is a higher heart rate at a given pace. Fortunately, your body adapts to higher altitude in several days to 2 weeks, but if you’re only at altitude briefly, you’ll need to slow your pace to keep your heart rate in the proper range. It also takes longer to recover from a hard effort at altitude, so rest periods may need to be longer.

Fuel. Your body is always using a combination of carbohydrates, fats and proteins for energy production. As the exercise intensity increases, you burn more carbohydrates and less fat (protein metabolism is always fairly small). Even at low intensities, you need some carbohydrate to burn fats (fats burn in the flame of carbohydrate). What does this have to do with heart rate? If you start to run low on carbohydrate, it will become difficult to maintain your pace at a given heart rate. Your perceived exertion and subjective feeling will increase, but your heart rate will be falling. This is informally called “bonking” and can be remedied by eating foods high in carbohydrate. As a rule of thumb, always bring along some form of ingestible energy on any outing lasting more than 2 hours