Archive for November, 2006

Why You Might Be Getting Abnormal Heart Rate Readings When Exercising

Thursday, November 30th, 2006

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 or the heart rate stays at zero (0).

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.

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.

3. Electromagnetic disturbances

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.

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.

Care and Maintenance of Your Polar Heart Rate Monitor and Transmitter

Thursday, November 30th, 2006

The following suggestions help in maintaining the water resistance:
• Keep your unit clean.
• Wipe off any moisture before putting the unit away.
• Do not store the unit in non-breathable material (i.e. plastic bag or damp gym bag).
• Do not operate the buttons whilst under water or when wet.
• Keep your Polar Heart Rate Monitor out of extreme cold (below –10 º C/14 ºF) and heat (above 50 ºC/120 ºF).

• The first sign that the battery may be running down is when the display fades. This may become apparent when the digits fade when the back light is used (certain models).
• We recommend that you send your unit to the Polar Service. The rubber seal that ensures water resistance should be checked and the unit should be tested for water resistance every time it is opened.
• Service to your unit by yourself or an unauthorized service may damage your unit.
• Warranty does not cover damage or consequential damage caused by service not authorized by Polar.

• Wash and dry your transmitter after use. To maximize the battery life do not store your transmitter in a damp environment or with conductive material such as a wet towel.
• Readjust the elastic strap periodically so that the transmitter fits firmly around the chest. The strap needs to be replaced every one to two years.
• Do not stretch or bend the transmitter. This may damage the electrodes.
• Clean the transmitter belt regularly with a mild soap and water solution. Never use alcohol or any abrasive material such as steel wool or cleaning chemicals on any part of the HRM.
• If your T31 transmitter does wear out, a new one is available at the Polar Heart Rate Monitor Store at If your WearLink Transmitter strap wears out, you can also purchase one in the Store. If your WearLink Transmitter needs a new battery, please send it to Polar USA at this address:
Polar Electro Inc.
1111 Marcus Avenue,
Suite M15 Lake Success, NY 11042-1034
Attn: Service Center (800) 227-1314 (tel) (516) 364-5454 (fax)

Why Polar Chose the S1 Foot Pod Technology Instead of GPS

Thursday, November 30th, 2006

Q: Why didn’t Polar use GPS technology for speed and distance for the S625X Running Computer and the new RS400sd?
We considered both GPS and inertial technologies carefully before choosing to go with inertial technologies. GPS has some positive elements but we chose the best overall technology for running anywhere and in any conditions. We recognized that existing GPS was too heavy and consumed too much power for an application that was meant for runners who are demanding and relatively heavy users and train frequently. Existing GPS applications are simply not as practical for someone who is running frequently because of the need to constantly recharge/replace batteries and because of the discomfort of hauling abound a large GPS unit on the upper body. When used in a real life running scenario- GPS is no more accurate that inertial sensor technology. With inertial technology we saw that we could provide the best solution for runners who want accurate and reliable speed and distance measurement that performs in all conditions (indoors and outside), in urban city settings with tall buildings, even in very heavily wooded trails and twisting turning trails and tight turning paths.
Q: GPS technology is considered advanced by many. What about the Polar inertial sensor technology that Polar uses?
The inertial technology that Polar uses is very advanced, inertial technology is used in aerospace positioning and guidance systems, industrial robotics and in advanced automotive applications such as active suspensions and emergency airbag deployment to name a few. The inertial sensors measure the acceleration of the S1 foot pod more than 1000 times per second and use this data with advanced algorithms to calculate foot angles and gait velocity the Polar S1 running speed and distance sensor is NOT A PEDOMETER. Instead, it is very advanced running speed sensor.
Q: GPS provides speed and distance while running, cycling and even during X-C skiing. What about the Polar S625X?
The Polar S625X was designed primarily for runners and tri-athletes. So we have ensured that the running functions are optimized for running and cycling. The S625X is fully compatible with all Polar cycling sensors. Combining cycling speed and cadence and power options provides many more dimensions to the cycling cross-sports experience than that offered by GPS speed and distance unit.
Q: Some GPS units provide directional features to help navigation. Why has Polar opted to leave this out in the S625X? The S625X was designed with the knowledge that 80% of runners generally run the same 3-5 routes. The speed and distance element of the S625X will support people who want to track speed and distance on these routes and also lets them find more new routes with no need for external mile markers. Navigation features are best suited for outdoor and adventure products, while the S625X is focused on providing runners the most relevant features for building performance and enhancing their every running experience.
Q: Is the S1 footpod heavy? You can’t feel it when once its attached to your shoe. Infact, you will struggle to figure out (by feel) which shoe has the footpod on it once you put it on. The Polar S1 footpod is built to last with robust water resistance, shock resistance and easy battery change while still not reducing shoe comfort or running performance.
Q: How accurate is the S625X? Generally the S625X is at minimum 97% accurate even without calibration. The accuracy increases to 99% with calibration. In relative terms, this accuracy is as good or better than the accuracy provided by GPS. Interestingly, this degree of accuracy is generally far better than what is seen on running treadmills. Have you ever heard of a runner complain that a treadmill was not accurate enough for their training purposes?
Q: Do I need to re-calibrate my footpod everytime my foot pod or wrist unit battery is changed? If you choose to calibrate your Polar S1 foot pod, the calibration factor will be stored in the permanent memory of the S625X Running Computer. This calibration will be stored permanently, unless you decide to change it….so if you calibrate, you only need to do it once.
Q: Will the Polar S1 foot pod leak water? Robust water-resistance and durability are key elements in the design of the Polar S1 foot-pod. It will survive immersion, wet running environments and continue to perform reliably. However, the S1 was not designed for swimming or aqua-running so please do not going swimming with it.
Q: What is the foot pod battery lifetime? The battery lifetime is 20 hours of use in average.
Q: How do I know that the foot pod battery needs to be replaced? When the green light on the foot pod turns red, you need to replace the battery. Replace the battery in case the foot pod does not start or the running speed shows 00 constantly.
Q: Can I replace the battery myself and if so, what is the battery type? The foot pod is designed so that the user can replace the battery him/herself without tools.The battery type is AAA. You can learn more about Polar running heart rate monitors with the S1 Foot Pod at - - as well as the Polar RS800sd with the S3 Foot Pod by going to