Suunto Smart HR Belt - Beware module orientation - HRV and ZoneSense
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Ever since I bought the “Suunto Smart Heart Rate Belt” I have been extremely diligent in keeping the module oriented correctly, following the manual instructions:
“Suunto Smart Heart Rate Belt User Guide”:
“Putting on belt
[…]
4. Put the belt on so that it fits tightly and the Suunto logo is facing up.”This has worked well, with little problems regarding both Puls and Heart Rate Variability. A typical HRV curve looks like the Runalyze graph below, which only has 0,8 % Anomalies. And that is what Suunto ZoneSense really craves; reliable data:
Today I returned home after a short Run session and realised that I had snapped the HR module on upside down. Well, I thought, it shouldn’t make much of a difference since (to my knowledge) there are no other sensors present - like gyroscopes or accelerometers. But when looking at the ZoneSense graph I really stood corrected! This is not a normal result in my case:
And although Runalyze claim that the session only had 0,7 % Anomalies, the graph looks rather suspect:
Using the ‘fill screen’ button to zoom in on the graph, we see even clearer that the main line is surrounded, above and below, by two fuzzy ‘ripple’ or ‘echo’ areas:
So, not only are we in danger of getting bad HRV data through the usual channels like dry belts, poor belt contacts, static electricity, worn-out belts asf, with the Suunto belt, module orientation is imperative. This surprised me to such a degree that I felt compelled to write this forum post.
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@Inge-Nallsson said in Suunto Smart HR Belt - Beware module orientation - HRV and ZoneSense:
(to my knowledge) there are no other sensors present - like gyroscopes or accelerometers
not sure this is true, by searching on the Movesense web site it seems that all their devices have also movement sensors (3 axes):
https://www.movesense.com/movesense-sportconcerning the HR/HRV only measurements I also expect that flipping the module shouldn’t affect the measurements …
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@Stefano-M64 Thank you for the Movesense link. Now I know that they normally are packed with sensors! And the company provide datasheets by e-mail if you give them a lot of information in return…
The flipping result is indeed surprising. The example of a normal HRV graph I posted was from Saturday, chosen because of the Run session length being closer to today’s than the session length yesterday which I’ll provide as an OK evidence below. 0.0% Anomalies according to Runalyze:
There are some scattered readings but nothing that affected ZoneSense:
There is very little chance that the HR belt got worn-out from yesterday to today, but if I get bad HRV data with a correctly positioned module tomorrow I’ll be sure to edit the first post with a strikeout of all incorrect text
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@Inge-Nallsson I got this scattered reading when my heart is skipping. I have an implanted ECG monitor and have been diagnosed with ventricular extrasystole, along with occasional short pauses in my pulse. When I feel my heart skipping during running or cycling, and then later look at the R-R interval chart or successive differences chart, I can clearly see the symptoms at the exact moments I felt them. Many people have this condition and don’t feel anything. I’m “lucky” enough to feel every single extrasystole
— and sometimes it’s very annoying. It shouldn´t be dangerous if there are no other symptoms. But sometimes I got this reading even with no symptoms, when I feel good and that must be anomalies.This is run with my problems, 0.1% anomalies, successive differneces:
And another one without that feelings, 0% anomalies:
Cycling with very strong heart skipping at start (long uphill), exhausted from previous ride and work on cottage, 0% anomalies:
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@Jan-Suchánek wow, those are very good readings, are you using Suunto HR belt?
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@Likarnik No, sorry. I realized, that my answer is off topic, because I use Polar H10 strap. Always make it wet with ultrasound gel and moved about 5cm to the left breast. This makes the highest voltage reading to me. Tried with FatMaxxer app.
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@Jan-Suchánek great for offtopic as I also use h10
