The sports accessories available on the shelves nowadays are nothing like those we had to deal with a few years ago. They not only provide the most important parameters, but also make various advanced measurements, such as heart rate. An interesting solution are optical heart rate sensors – what is it?
Until recently, in order to count the number of heartbeats it was necessary to measure the frequency of electric impulses during the contraction of the heart muscle. For this purpose, a special strap worn on the chest was used. Although this solution is extremely precise, it is not the most comfortable one. To meet the expectations of the most demanding customers, manufacturers of sports equipment have introduced a method of heart rate measurement that does not require the use of the aforementioned belt. We are talking about an optical heart rate sensor.
Don’t you like heart rate measuring belts put on your chest? Polar has a solution for that. Polar OH1 is an optical heart…
Published by Active Wrist Thursday, November 2, 2017
A number of different factors influence the precision of the heart rate measured from the wrist. We can influence some of them, but not others. A very important issue here is the place and strength of fastening the watch. It is worth realizing that the more soft tissue there is under the sensor, the better. This is due to the fact that there will be more veins there to make the necessary measurements. In the case of slim wrists, there is less tissue and therefore less precision.
It is important to make sure that the watch is fastened at a height so that the optical sensor for measuring heart rate is not located on the wrist bones. If you bend your hand upwards and the edge of your hand presses against the side of the watch envelope, this means that the device has been strapped too low. If you fasten the watch too tightly, the blood will not be able to flow freely in your veins. On the other hand, if you fasten it too lightly, light will get under the sensor, which will negatively affect the amount of light received by the photodiode. This will result in incorrect interpretation of signals.
Such a device should be fastened firmly enough so that it does not move on the wrist, no external light penetrates under it, and lightly enough so as not to disturb the blood flow in tissues. In order to ensure that the measurement is as precise as possible it is advisable to remove any hair from the area where the sensor meets the skin. This will positively influence the adjustment of the device equipped with an optical heart rate sensor, at the same time revealing the light emitted from the light-emitting diodes.
Factors beyond our control include the amount of pigment in the skin and tattoos. The pigment absorbs more light, which makes the amount of reflected light smaller, resulting in less precise measurement.
It is also worth mentioning sports and exercises that require the hands to be held above the heart line, such as pull-ups. As the hands are then directed upwards, blood does not flow efficiently due to gravity, which may negatively affect the accuracy of measurement.
Another factor that is beyond our control is the high level of vibration, such as that experienced while riding a motorcycle. They can make the optical heart rate sensor detach from the surface of the wrist.
The next important factor is the flexing of the wrist while cycling. This results in blood vessels closing and problems with free blood flow. It is worth realizing that the measurement from the wrist will be the most precise when the heart rate does not undergo sudden changes. Therefore, an optical heart rate sensor will work best during recreational cycling or long runs.
Featured Photo: StockSnap / Pixabay
