RCX5 User Manual


Polar Sport Zones

Polar sport zones introduce a new level of effectiveness in heart rate-based training. Training is divided into five sport zones based on percentages of maximum heart rate. With sport zones, you can easily select and monitor training intensities.

Target zone

Intensity % of HRmax, bpm

Example durations

Training benefit



171–190 bpm

less than 5 minutes

Benefits: Maximal or near maximal effort for breathing and muscles.

Feels like: Very exhausting for breathing and muscles.

Recommended for: Very experienced and fit athletes. Short intervals only, usually in final preparation for short events.



152–172 bpm

2–10 minutes

Benefits: Increased ability to sustain high speed endurance.

Feels like: Causes muscular fatigue and heavy breathing.

Recommended for: Experienced athletes for year-round training, and for various durations. Becomes more important during pre competition season.



133–152 bpm

10–40 minutes

Benefits: Enhances general training pace, makes Moderate intensity efforts easier and improves efficiency.

Feels like: Steady, controlled, fast breathing.

Recommended for: Athletes training for events, or looking for performance gains.



114-133 bpm

40–80 minutes

Benefits: Improves general base fitness, improves recovery and boosts metabolism.

Feels like: Comfortable and easy, low muscle and cardiovascular load.

Recommended for: Everybody for long training sessions during base training periods and for recovery training sessions during competition season.



104–114 bpm

20–40 minutes

Benefits: Helps to warm up and cool down and assists recovery.

Feels like: Very easy, little strain.

Recommended for: For recovery and cool-down, throughout training season.

HRmax = Maximum heart rate (220-age). Example: 30 years old, 220–30=190 bpm.

Training in heart rate zone 1 is done at a very low intensity. The main training principle is that performance improves when recovering after, and not only during training. Accelerate the recovery process with very light intensity training.

Training in heart rate zone 2 is for endurance training, an essential part of any training program. Training sessions in this zone are easy and aerobic. Long-duration training in this light zone results in effective energy expenditure. Progress will require persistence.

Aerobic power is enhanced in heart rate zone 3. The training intensity is higher than in sport zones 1 and 2, but still mainly aerobic. Training in sport zone 3 may, for example, consist of intervals followed by recovery. Training in this zone is especially effective for improving the efficiency of blood circulation in the heart and skeletal muscles.

If your goal is to compete at top potential, you will have to train in heart rate zones 4 and 5. In these zones, you exercise anaerobically in intervals of up to 10 minutes. The shorter the interval, the higher the intensity. Sufficient recovery between intervals is very important. The training pattern in zones 4 and 5 is designed to produce peak performance.

The Polar target heart rate zones can be personalized by using a laboratory measured HRmax value, or by taking a field test to measure the value yourself. When training in a target heart rate zone, try to make use of the entire zone. The mid-zone is a good target, but keeping your heart rate at that exact level all the time is not necessary. Heart rate gradually adjusts to training intensity. For instance, when crossing from heart rate target zone 1 to 3, the circulatory system and heart rate will adjust in 3-5 minutes.

Heart rate responds to training intensity depending on factors such as fitness and recovery levels, as well as environmental factors. It is important to look out for subjective feelings of fatigue, and to adjust your training program accordingly.

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Heart Rate Variability

Heart rate varies with every heartbeat. Heart rate variability (HRV) is the variation of beat to beat intervals, also known as R-R intervals.

HRV indicates the fluctuations of heart rate around an average heart rate. An average heart rate of 60 beats per minute (bpm) does not mean that the interval between successive heartbeats would be exactly 1.0 sec, instead they may fluctuate/vary from 0.5 sec up to 2.0 sec.

HRV is affected by aerobic fitness. HRV of a well-conditioned heart is generally large at rest. Other factors that affect HRV are age, genetics, body position, time of day, and health status. During exercise, HRV decreases as heart rate and exercise intensity increase. HRV also decreases during periods of mental stress.

HRV is regulated by the autonomic nervous system. Parasympathetic activity decreases heart rate and increases HRV, whereas sympathetic activity increases heart rate and decreases HRV.

HRV is used in the OwnIndex and ZoneOptimizer features.

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Polar ZoneOptimizer

Polar ZoneOptimizer feature adopts this principle as it recommends lower intensity training when little heart rate variability is detected and higher intensity training, when plenty of heart rate variability is detected. It also gives you feedback on daily physiological status (good/normal/low) in respect to the amount of heart rate variability measured when compared to earlier measurements.

Benefits of the ZoneOptimizer feature

Each Sport Zone has a different physiological response which is described briefly in the Polar Sport Zones . The measurement takes your current physiological state into account and changes Sport Zones values so that it is more certain for you to get the same physiological response when training in specific Sport Zones on different days. This means that when training in optimized Sport Zones the training intensity is adjusted to match the daily physiological status of your body.

ZoneOptimizer measurement

Polar ZoneOptimizer recommends lower intensity training when little heart rate variability is detected and higher intensity training, when plenty of heart rate variability is detected at a given heart rate. It also gives you feedback if your current limits are higher, normal or lower than your normal level, when compared to your earlier measurements. You may get feedback on your daily physiological status by paying attention to how fast and how easily you can do training at the recommended heart rates.


Heart rate in beats per minute


How to achieve

Keep your heart rate between 70 and 100 beats per minute.

70 - 100 bpm

2 minutes

Standing or training with very light training intensity, for example, walking slowly.

Increase heart rate gradually from 100 to 130 beats per minute within two minutes.

100 - 130 bpm

2 minutes

Walking briskly or cycling/ jogging at low intensity during warm up.

Gradually increase your heart rate above 130 beats per minute.

130 bpm <

At least 30 seconds

Gradually increase your heart rate and continue as planned. The ZoneOptimizer determination will finalize in one minutes time.

Measurement phases

Target zone limit determination is done in three phases.

  1. Preparing for training session and plenty of heart rate variability exists. As there is a lot of heart rate variability, this is a very good and sensitive phase to detect daily changes. In absolute figures this means heart rates from 70 to 100 beats per minute.

  2. Warming up, heart rate rises slowly and heart rate variability drops. During this phase heart rate variability starts dropping, and the body prepares for higher intensities. In absolute figures this means heart rates from 100 to 130 beats per minute.

  3. Heart rate variability levels off. After this phase heart rate variability stays at a very low level or almost disappears. This usually takes place at around 130 beats per minute and higher. All Zone limits are updated after heart rate has been continuously, for at least 30 seconds, above the upper limit of Phase2 (130 beats pre minute / 75% of HRmax).

ZoneOptimizer guidance normally uses absolute figures (70-100-130 beats per minute), but the two uppermost figures change if personal HRmax is very low. The second phase upper limit, which is normally 130 beats per minute, is limited not to exceed 75% of HRmax. This is done automatically without actions from you.

ZoneOptimizer allows different durations of Phase1 (preparing for training session, heart rate in between 70-100 beats per minute) and Phase2 (warming up, heart rate in between 100-130 beats per minute). The recommended minimum durations to get the limits successfully determined are 2 minutes at Phase1, 2 minutes at Phase2 and half a minute or more in Phase3.

ZoneOptimizer function is developed for the use of healthy people. Some health conditions may cause heart rate variability-based ZoneOptimizer determination to fail or give lower intensity targets. These conditions include high blood pressure, cardiac arrhythmia, and certain medications.

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Maximum Heart Rate

Maximum heart rate (HRmax) is the highest number of heartbeats per minute (bpm) during maximum physical exertion. It is individual and depends on age, hereditary factors, and fitness level. It may also vary according to the type of sport performed. HRmax is used to express training intensity.

Determining Maximum Heart Rate

Your HRmax can be determined in several ways.

  • The most accurate way is to have your HRmax clinically measured, usually on a maximal treadmill or by taking a bicycle stress test supervised by a cardiologist or an exercise physiologist.

  • You can also determine your HRmax by taking a field test together with a training partner.

  • You can obtain a HRmax-p score that predicts your HRmax by taking the Polar Fitness Test.

  • HRmax can also be estimated by using the commonly used formula: 220 - age, although research shows that this method is not very accurate, especially for older persons or those who have been fit for many years.

If you have done some hard training in recent weeks and know that you can safely reach maximum heart rate, you can safely take a test to determine your HRmax yourself. Having a training buddy with you during the test is recommended. If you are uncertain, consult your physician before undertaking the test.

Here is an example of a simple test.

Step 1: Warm up for 15 minutes on a flat surface, building up to your usual training pace.

Step 2: Choose a hill or stairwell that will take more than 2 minutes to climb. Run up the hill/steps once, building to as hard a pace as you can hold for 20 minutes. Return to the base of the hill/steps.

Step 3: Run up the hill/steps again, building towards a pace you could just about hold for 3 kilometers. Note your highest heart rate. Your maximum is approximately 10 beats higher than the noted value.

Step 4: Run back down the hill, allowing your heart rate to drop 30-40 beats per minute.

Step 5: Run up the hill/steps once again at a pace that you can only hold for 1 minute. Try to run halfway up the hills/steps. Note your highest heart rate. This brings you close to your maximum heart rate. Use this value as your maximum heart rate to set training zones.

Step 6: Make sure you get a good cool-down, a minimum of 10 minutes.

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Running Cadence and Stride Length

Cadence* is the number of times the foot with the stride sensor* hits the ground per minute.

Stride length* is the average length of one step. That is the distance between your right and left foot contacting the ground.

Running speed = 2 * stride length * cadence

There are two ways to run faster: moving your legs at a higher cadence or taking longer steps.

Elite long distance runners typically run with a high cadence of 85-95. On uphills, typical cadence values are lower. On downhills they are higher. Runners adjust stride length to gather speed: stride length increases as speed increases.

Yet one of the most common mistakes novice runners make is over-striding. The most efficient stride length is the natural one – the one that feels most comfortable. You will run faster in races by strengthening your leg muscles so they take you forward with a longer stride.

You should also work on maximizing cadence efficiency. Cadence does not progress easily, but if properly trained, you will be able to sustain it throughout your runs and maximize your performance. To develop cadence, the nerve-muscle connection needs to be trained - and reasonably frequently. A session of cadence training a week is a good start. Incorporate some cadence work into the rest of your week. During long easy runs, you could include some faster cadence every now and then.

When training for longer running events (½ marathon, marathon or longer), it may be helpful to monitor cadence. A low cadence at expected race pace can cause problems later in the event, as your legs tire. One way around this is to work on increasing leg speed at expected race pace. You can set your training computer to show pace and cadence. Try to shorten your stride and increase cadence while holding the same pace (set a narrow pace zone to give you audio feedback).You can aim to raise running cadence above the following:

  • 80/min (4 hour marathoners)

  • 85/min (3 hour 30 min marathoners)

  • 88/min (3 hour marathoners)

This is a general guide only, taller runners will naturally have slightly lower cadences. Runners should also tune in to what feels comfortable for them personally.

A good way of improving stride length is to undertake specific strength work, like running hills, running in soft sand, or running up steps. A six-week training period including strength work should result in noticeable improvements in stride length, and if combined with some faster leg speed work (such as short strides at best 5km pace), noticeable improvements should be seen in overall speed, as well.

*Optional s3+ stride sensor required.

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Polar Running Index

Running Index offers an easy way to monitor performance changes. Performance (how fast/easily you run at a given pace) is directly influenced by aerobic fitness (VO2max) and training economy (how efficient your body is at running), and Running Index is a measurement of this influence. By recording your Running Index over time, you can monitor progress. Improvement means that running at a given pace requires less of an effort, or that your pace is faster at a given level of exertion. The Running Index feature calculates such improvements. Running Index also gives you daily information on your running performance level which may vary from day to day.

Benefits of Running Index:

  • emphasizes the positive effects of good training sessions and resting days.

  • monitors fitness and performance development at different heart rate levels - not only during maximal performance.

  • you can determine your optimal running speed by comparing running indexes from different kinds of training sessions.

  • stresses progress through better running technique and fitness level.

Running Index is calculated during every training session when heart rate and the s3+ stride sensor/G3/ G5 GPS sensor* signal is recorded, and when the following requirements apply:

  • speed should be 6 km/h / 3,75 mi/h or faster and duration 12 minutes minimum.

  • heart rate should be above 40% HRmax.

Make sure that the stride sensor is calibrated. Calculation begins when you start recording the session. During the session, you may stop once at traffic lights, for example, without interrupting the calculation.

In the end, your training computer displays a Running Index value and stores the result in the Training files section. Compare your result to the table below. Using the software, you can monitor and analyze your progress in Running Index values against time and different running speeds. Or compare values from different training sessions and analyze them in short and long term.

Short-term analysis

Running Index

Performance Level

< 30 - 30

Very poor










Very good

> 65


There may be some daily variation in the Running Indexes due to running circumstance changes, for example different surface, hills, wind or temperature.

Long-term analysis

The single Running Index values form a trend that predicts your success in running certain distances.

The following chart estimates the duration that a runner can achieve in certain distances when performing maximally. Use your long-term Running Index average in the interpretation of the chart. The prediction is best for those Running Index values that have been received at speed and running circumstances similar to the target performance.

Running Index

Cooper test (m)

5 km (h:mm:ss)

10 km (h:mm:ss)

21.098 km (h:mm:ss)

42.195 km (h:mm:ss)





































































































































*Optional s3+ stride sensor or G3/G5 GPS sensor required.

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Polar Training Load Feature

The training load feature in the calendar view in polarpersonaltrainer.com will conveniently tell you how hard your training session was, and how much time is needed for complete recovery.This feature tells you if you have recovered enough for your next session, helping you find the balance between rest and training. In polarpersonaltrainer.com you can control your total workload, optimize your training, and monitor your performance development.

Training load takes into consideration different factors which affect your training load and recovery time, such as heart rate during training, duration of training, and your individual factors, e.g. sex, age, height, and weight. Continuous monitoring of training load and recovery will help you recognize personal limits, avoid over or under training, and adjust training intensity and duration according to your daily and weekly targets.

Training Load feature helps you to control total workload, optimize your training, and monitor your performance development. The feature makes different kinds of training sessions comparable with each other, and helps you to find the perfect balance between rest and training.

For more information on Training load, see polarpersonaltrainer.com Help.

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Polar Endurance Training Program for Running and Cycling

Polar has created tailored Endurance training programs for running and cycling, which are available for you in polarpersonaltrainer.com. You get a personalized training program to best suit your current fitness level.

Endurance training programs are ideal for you, if running or cycling is incorporated in your main fitness routine. Endurance programs improve cardiovascular fitness and are not targeted to any sport event.

Endurance training programs are continual i.e. the program will continue as long as you want to stop it. The program guides you to train in the correct way by defining the training volume, training intensity and training placement on weekdays, for the optimal fitness improvement.

Training program works together with the ZoneOptimizer feature, which means that program training sessions are modified according to your present condition i.e. your physical condition and recovery from previous training sessions are taken into consideration. For more information, see Polar ZoneOptimizer.

Suitable Program Starting Level for Everybody

Program level must be known before a suitable training module can be selected. The determination of the program level can be done:

  • automatically using your previous training history in polarpersonaltrainer.com

  • or using a short questionnaire which you will have to fill in.

General programs are compiled of 4 week long training modules. Training module in level 1 is the least demanding and the module in level 20 is the most demanding. Steps between 1-20 are linear, which means that you can improve your fitness step by step (for example from level 7 to level 8 et cetera).

Training modules and your training activity are linked together so that training modules get more challenging as your training activity increases, and also less challenging if your training activity decreases.

Beginner stage consists of levels 1-5. At this stage the 4 weeks training module contains mainly medium and long training sessions; interval training sessions are given from level 5 onwards.

Moderate stage consists of levels 6-10. At this stage the 4 weeks training module contains mainly medium, long and interval training sessions; tempo training sessions are given from level 11 onwards.

Advanced stage consists of levels 11-20. At this stage the 4 weeks training module contains mainly medium, long, interval and tempo training sessions; easy training sessions are given from level 12 onwards.

For more information on Polar Endurance training programs see polarpersonaltrainer.com Help.

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Polar Training Articles

For more facts and know-how to enhance your running, visit Polar Article Library .

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