Last Updated on December 1, 2023 by pg@petergamma.org
When Polar released the Polar OH1 the battery running time was about 8 hours. To use this device 24 * 7 requires 3 fully charged Polar OH1. Then Polar released the Polar OH1 successor Verity Sense. The battery running time of the Verity Sense was longer than that of the Polar OH1, but shorter than 24 hrs. Garmin OHMs for instance have battery running times which are longer than 24 hrs which requires only one charge for running it 24 hrs. We wrote in the DC Rainmaker blog some time ago that we miss a non-wrist based optical heart rate monitor from Polar which runs more than 24 hrs:
https://www.dcrainmaker.com/2021/02/polar-verity-sense-optical-hr-sensor-band-in-depth-review.html
Shortly after that Polar increased the running time of the Verity Sense by a firmware update which made the Verity Sense run more than 24 hrs.We could not believe this. How can Polar change the specifications of the Verity Sense by a firmware update? The Verity Sense predecessor Polar OH1 was validated in scientific study in PLOS ONE with a g.tec medial multi purpose device which costs 50 000 USD. Who writes validation papers about OHRMs before and after a firmware update? Eventually Polar developers who do not publish their results, but who else?
This procedure of Polar lead us doubt about the Verity Sense. Is this really a completely new sensor than the Polar OH1? It runs longer, but the size of the sensor is the same as of the Polar OH1. Is it possible to increase the running time of a heart rate monitor without increasing the size of the battery? Yes for instance by decreasing the sampling rate, which means how often the sensor makes a measurement in a certain time interval. But does this not lead to a decrease in accuracy? Usually this is so. It is possible to decrease the sampling rate optical heart rate monitors also by the user himself. Also Garmin watches decreases the sampling rate for activity tracking compared to the sampling rate during activities. We have no proof for this this is our hypothesis. This makes those devices run in activity tracking mode for near to one week. But we suppose this decreases the accuracy, but we do not know of any scientific studies who tested this.
But does it make any sense for Polar to reduce the accuracy of a HRM with a firmware update which is mesuarable? No, which company who is interested to have heart rate monitors of the highest accuracy does this? We therefore suppose that the accuracy of the Polar OH1 has already reached the limit of what is technologically possible with this architecture. Since there is no evidence that the Verity Sense has a bigger battery than the Polar OH1 we suppose the longer battery life was obtained by using different algorithms. We do not know of any substantial scientific progress which would make optical heart rate monitors more accurate since the Polar OH1 which has been published in scientific papers.
But what whas new is the PhD. thesis of Paul Van Gent:
https://scholar.google.com/citations?user=OOhuA6gAAAAJ&hl=de&oi=sra
who developed HeartPy: A novel heart rate algorithm for the analysis of noisy signals:
https://www.sciencedirect.com/science/article/abs/pii/S1369847818306740
Better algorithms for the analysis of noisy signals make OHRMs more accurate. Our hypothesis is therefore that Polar integrated Paul Van Gents HeartPy algorithms in the Verity Sense to increase the running time but not the accuracy, which means that Polar kept the accuracy constant while increasing the running time.
At about the same time Apple was able to increase the accuracy of their wrist based watches to values which are higher than the values of the non-wrist based Polar OH1 and Verity Sense. It was argued that the Polar OH1 and the Verity Sense are non-wrist based sensors since wrist based sensor ar not an optimum of accuracy matters. Or hypothesis is therefore that Polar integrated HeartPy algorithms in the Verity Sense to make it run longer than the Polar OH1. On the other hand Apple integrated these algorithms in their wrist based devices to make the Apple watches more accurate. But we have only the data of Rob ter Horst for this hypothesis. We do not know of any scientific studies who would confirm this.
But why did scientists not study these topics in scientific papers? If these increases in running time and accuracy would be of interest for scientists would they not have performed scientific studies about it and publish it? But we do not know of such studies. The only scientist which made a big story about it was Rob ter Horst who discussed this topic in great detail on his his YouTube videos but without having any numerical and statistical data to proof his observations. But if Rob ter Horsts observations would be of interest for other scientists would they not have performed scientific studies to investigate this? But we do not know of such studies.
Did these paper authors do some scientific tests to find out that there are no major changes in these new optical heart rate monitors which would make it interesting to write a new validation paper about it?
Our hypothesis is therefore that Polar increased the running time of the Verity Sense and Apple increased the accuracy ot the Apple watches by using better algorithms which have become available in recent years. So what now – as long as there are no new high quality validation papers which show that these new heart rate monitors are more interesting for scientists than the old ones. On the contrary the study of the scientific papers about these heart rate montors lets us conclude that these have become more accurate in recent years but not in a way so that companies who sell devices for scientific research such as iWorx, Adinstruments, Biopac or g.tec medical would have picked those up to sell those for scientific research or would have developed devices which are similar to those to sell those as their own products.