FAQ - INCORRECT HEART RATE READINGS

There can be several reasons for abnormal or irregular readings during exercise. Due to the same reasons, heart rate may stay at the same value for a long time, the heart rate stays at zero (0) or a very high reading (230).

1. Poor contact between the skin and the electrodes of the transmitter

For accurate heart rate measurement, the contact between skin and the electrodes should be as good as possible. Polar transmitters measure the ECG signal from the chest, where it is the strongest. The weak heart-generated signals need to be accurately measured before the calculation of the heart rate. It is therefore important to ensure that the contact between the skin and the electrodes is as good as possible. Here are some tips how to ensure good contact:

1.1. Moisten the grooved electrode areas on the back of the transmitter. At the beginning of the exercise session your skin may be dry and the moisture will help ensure better contact. When you start to sweat the contact will improve because the salt in the sweat conducts the electrical signals very well. Saliva is a good conductor as well.

1.2. Tighten the elastic strap of the transmitter. If the transmitter is loose, the movement of the electrodes disturbs the detection of the ECG signal. If the standard strap does not fit satisfactorily, larger and smaller elastic straps are available as accessories.

1.3. The type of the ECG signal slightly varies from person to person. The form of the ECG signal can depend on form of the chest, the anatomical location and position of the heart, position of the electrodes and the amount of body fat. If the ECG signal is weak, disturbances can more easily spoil the signal. Find the best contact by turning the transmitter left or right, or place it lower or higher. There have been cases where the transmitter detects the heart rate better when it is turned upside down so that the Polar logo is upside down and facing out, or even when attached on the persons back with the Polar logo upside down and facing out.

1.4. For active sports like aerobics or marathons, women can use the accessory Heart Bra which makes the transmitter stay in place better. Ask your local Polar dealer or distributor for the availability of this product.

1.5. Hairy chest may also weaken the contact. Try to find the best possible position for transmitter.

1.6. In demanding cases, use conductive electrode lotion or gel to improve the contact. After using them, it is very important to wash the transmitter carefully.

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2. Wear and tear of the transmitter

Proper care of the transmitter after use ensures longer service life for the transmitter.

2.1. Wash the transmitter regularly after use with a mild soap and water solution. Dry it carefully with a soft towel after washing.

Never store the transmitter when it is wet. Sweat and moisture can keep the electrodes wet and the transmitter activated, which shortens the battery life.

2.2. Store your Polar heart rate monitor in a cool and dry place. Make sure that the electrodes do not contact anything damp, such as sport towel or wet elastic strap. Do not store a wet transmitter in any kind of non-breathing material, such as a plastic bag or a sports bag.

2.3. Do not bend or stretch the transmitter. This may damage the electrodes.

2.4. Only dry the transmitter with a towel. Hard-handed handling may damage the electrodes.

2.5. Keep your Polar heart rate monitor out of extreme cold and heat. The operating temperature is -10 ºC to 50 ºC/ 14 ºF to 122 ºF. Do not expose the Polar heart rate monitor to direct sunlight for extended periods, such as leaving it in a car.

2.6. The transmitter can be washed with mild soap and a gentle brush. If the electrodes appear discoloured, the transmitter needs to be washed. Do not use any alcohol or a solvent based detergent.

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3. Electromagnetic disturbances

Sources of electromagnetic signals can cause erratic and faulty heart rate readings. Electromagnetic disturbances may occur near high voltage power lines, traffic lights, the overhead lines of electric railways, electric bus lines or tram lines, televisions, car motors, bike computers, some motor driven exercise equipment, cellular phones or when you walk through electric security gates. Check your surroundings and move away from the source of interference, or remove the source of the disturbance.

4. The distance between the transmitter and the receiver is too great

The maximum transmission range between the transmitter and the receiver is 1 metre (3 ft). If the distance is greater, the receiver may not get all the signals sent from the transmitter. In cases where the transmission range is at it is extremes, for example rowing or biking where the receiver is not attached to the wrist, the receiver may display the same heart rate for a long time. To avoid this, keep the distance within 1 metre.

5. Signals from more than one Polar Transmitter within 1 metre transmission range
Note only with non-coded transmitter (T31)!

In cases where are more than one transmitter nearer than 1 meter, and you are using the non-coded transmitter, your receiver can pick up the signal from all transmitters within the range, this can result abnormal high readings. Even if the other transmitter is coded, and yours is non-coded, your receiver may still give an inaccurate reading. To avoid signal crosstalk, keep the distance to the other transmitters.

The coded transmitter and receiver system does not pick up the signal from other heart rate monitors. In case of false readings with a coded transmitter and receiver, check if the code has been locked. After a successful code search, a frame will appear around the heart symbol on the display. If the frames around the heart cannot be seen start the measurement again and check that you are not near other heart rate monitor users, because they may interfere the code search. Also, high voltage power lines, televisions, mobile phones and other sources of electromagnetic disturbance may interfere with the code search, as well as keeping the receiver too close to the transmitter.

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6. Static electricity, technical sportswear and special conditions

If the humidity of the air is low, or you are exercising in windy conditions (for example high-speed road racing), a fluttering shirt may rub the transmitter and generate static electricity. This causes additional signals, especially if the contact between skin and transmitter is poor. To avoid this:

6.1. Moisten the electrodes before use, or use the conductive lotion or gel

6.2. Use a cotton shirt instead of a synthetic shirt

6.3. Use a tighter shirt to avoid fluttering of the material

6.4. Use the transmitter on a wet shirt

6.5. Wet the shirt

7. Arrhythmia

Polar Heart Rate Monitors are not designed to detect arrhythmia or irregular rhythms and will interpret them as noise or interference. The computer in the wrist receiver will make error corrections, so that arrhythmia beats are not included in the averaged beats per minute. The blinking heart symbol in the face of the wrist receiver, however, will continue to show all heart beats received. In most cases the Polar Heart Rate Monitors will work fine for persons with arrhythmia.

8. Battery of the transmitter is getting empty

The estimated average battery life of the Polar Transmitter is 2500 hours of use. If the battery of the transmitter is running low, the transmission range decreases and may cause errors similar to the ones listed above in this document. See more on the Battery empty in the Polar Transmitter document.

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