Suunto Smart Heart Rate Belt 2
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Today was an easy 35’ on the treadmill, my first run since a best-effort marathon 9 days ago. I did a factory reset of the SRMB2 before this run in hopes to address the early HRV chatter. I guess this is just my physiology. I don’t know what else to do.
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I guess this is just my physiology. I don’t know what else to do.
Well, you are not alone with this alleged incompatible physiology. I’ve now done multiple factory resets of the new SHRM2 unit and all my runs still start out with bad readings of the beat to beat data for the first 10 minutes. What really makes this a ‘sour grapes’ situation is the claim from Suunto about better HRV reading which should benefit the ZoneSense technology. Since ZS calibrates itself during the first 10 minutes can we, with the ‘physiology’, trust the ZS levels?
Another irritant is the inconsistency between HRV and HR. Sometimes the HRV is registered badly and the HR follows suit, e.g. getting stuck at about 90 bpm the fist 6 minutes. At other times the HRV is bad but the HR only exhibits a slight hiccup. For example my latest run where Runalyze claims 3.4% Anomalies:
But both the Race S and the Suunto App showed just this little dip down from 120 to 76 bpm after 3 minutes 13 seconds:
While the reality seen through the control watch (Forerunner 955 using OHR) was without a dip:
I am so tired of having to use a control watch!
FR955 Avg HR 128 bpm, Max 141. SHRM2 Avg HR 129 bpm, Max 141.
Edited: Changed the dip low bpm to real figure of 76 bpm (wrongly wrote 90).
Suunto Race S
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What really makes this a ‘sour grapes’ situation is the claim from Suunto about better HRV reading which should benefit the ZoneSense technology. Since ZS calibrates itself during the first 10 minutes can we, with the ‘physiology’, trust the ZS levels?
This is exactly why I ditched my Polar H10 for the Suunto SHRB2. I was getting consistent HRV noise in the first 10-15 minutes of every run. I always assumed this was electrostatic discharge from my shirt to the H10 module before my shirt got wet from sweat. But I’ve also had nothing but consistent battles with my H10 regardless, so I was eager to find something new.
When the SHRB2 was released with the promise that it had artifact rejection at the module, specifically addressing ESD, I was sold. But after wearing it, I’m seeing the same early HRV noise, despite moistening the strap, adding electrode gel, pre-run lunges, slightly shifting the module to the left, tightening and loosening the strap, and performing a factory reset.
Maybe it’s shirt fabric. I was wearing a 50/50 cotton/poly blend. I would hope the SHRB2 would be catching ESD at the module, but maybe it’s not. I should see if 100% cotton or linen shirts reduce my early HRV noise. If so, ESD might be the problem and the module isn’t doing what’s claimed. Or I’m misunderstanding the marketing.
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Maybe it’s shirt fabric. I was wearing a 50/50 cotton/poly blend. I would hope the SHRB2 would be catching ESD at the module, but maybe it’s not. I should see if 100% cotton or linen shirts reduce my early HRV noise. If so, ESD might be the problem and the module isn’t doing what’s claimed. Or I’m misunderstanding the marketing.
Please come later with results once you get them. My running T-shirts are all 100% poly and I have never saw any weirdness like this with Garmin HRM Dual (I have run with HRM about 300 km.)
Thanks!Suunto Race 2 Titanium
Garmin Forerunner 255 -
Maybe it’s shirt fabric. I was wearing a 50/50 cotton/poly blend. I would hope the SHRB2 would be catching ESD at the module, but maybe it’s not. I should see if 100% cotton or linen shirts reduce my early HRV noise
This is my latest R-R collection following the many good ones I had after the reset:
Apparently, something (who knows what) triggered this oddity. Also tried shirts made of 100% cotton or linen, and didn’t notice any difference compared to those made of polyester or other materials. Btw HR was spot on compared to H10
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While there definitely are effects of plastic shirts or dry skin, the RR measurement itself is rather simple. It is the exact milliseconds between heartbeats.
The calibration during the first minutes of an exercise is not calibration of the sensor. The sensor is just reading the time between heartbeats.
It is “calibration” of the body. Or better: reading what the base line of the individual body is. Everyone is different here…
Also HRV during activity is not something that changes quickly with effort as HR itself. This is the reason why the ZoneSense readings only make sense when running at a rather steady state and it does not work for short intervals. -
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Hello everybody,
First of all, I would like to ask an official Suunto representative:
Will Suunto Ocean support Running Form metrics from the Suunto Smart Heart Rate Belt 2 in a future firmware update?
Or will the data at least be available to Suunto Ocean users through the Suunto app?
Thank you in advance for your response. -
Really not what I hoped for:
Thats worse than most of my runs with the old belt. I soaked it in water, also little bit of gel for the electrodes and a lot of sweat. Belt was very tight.Zonesense couldn’t detect anything of course, but at least heart rate looks good compared to power and feeling. But still very underwhelming
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Please come later with results once you get them.
It was @atoponce who brought up shirt fabric and wondered about electrostatic discharges, but I thank you for the prodding which made me test the theory over three new running sessions!
The very first post in this SHRM2 thread quotes product sale blurbs from the site cam2.com.hk. One paragraph contains:
“Enhanced signal shielding prevents static electrical noise caused by dry performance fabrics”
A more generic description at us.suunto.com says at the Overview and Specifications sections:
“Trust Every Beat A new chest-strap construction shields the signal from static noise, holding readings stable from the first minute […] Module: Stainless steel cover plate + fiber reinforced composite material”
I can now confidently state that Suunto has failed, to a staggering degree, with this construction aim [Disclaimer: Using my SHRM2 unit in combination with my exercise clothes].
During the three Run/Walk sessions conducted because of injuries - and detailed in this thread - I used a 100% cotton T-shirt and an outer layer jacket being a blend of 80% cotton and 20% polyester. In spite of wetting both chest and strap with a high saline water solution (and doing a short warmup), all exercises had poor HRV data sections during the first 10 minutes, and one bad HR strangeness.
The Runalyze site lists (unexplained) something called Anomalies in percentage at the R-R intervals section, and Artifacts when clicking on DFA-a1. Since the exercise times were somewhat long, ca 1.5 hours, these numbers did not seem in excess:
An: 0.4%
Ar: 1.9%An: 0.5%
Ar: 1.8%An: 0.3%
Ar: 0.8%But when I started doing regular running, using a T-shirt of 100% polyester and a windbreaker jacket also of 100% polyester, the An/Ar numbers in the much shorter times (ca 20 - 27 minutes) became significant:
An: 5.4%
Ar: 8.7%An: 9.0%
Ar: 19.9%An: 3.4%
Ar: 7.3%Polyester rubbing against polyester can build up significant charges and the first two runs showed major HR faults at the first 4 to 6 minutes, the third only had the ‘little’ dip from 120 to 76 bpm at 3 minutes detailed in my previous posting. Prior to these runs I only ran the strap (both sides) under a water faucet and scooped the same water over my chest.
When this electrostatic discharges and shirt fabric question came up, I first extended the water routine to also running the whole front of the (100% polyester) T-shirt under the faucet. Sopping wet first layer! And that did a tremendous job of keeping the An/Ar numbers down:
An: 0.0%
Ar: 0.5%Here’s the complete R-R chart from Runalyze:
Not bad, eh? And the HR graph compared as a twin to the one from the control watch; Garmin FR955 using its OHR. But why stop there… During the 13.5 years I’ve done running exercises, both Garmin (all their 4 or 5 models of chest HR monitors I’ve owned) and Polar (the H10) have forced me to appreciate rubber as a solution to the chafing problem. Suuntos HR pod (previous small round one) and band was the first that did not rub the skin raw or completely off during longer runs. With the others I used a sleeve of inner tubing from an old bicycle tire. Cutting a small piece for the SHRM2, just covering the pod not any of the electrodes, I tried the easiest running session path I can find hereabouts, smooth asphalt and little undulations, for a 33 minutes out-and-back:
An: 0.0%
Ar: 0.2%
As can be seen, the result was even better than water on the T-shirt. No HR shenanigans at all. The two R-R zigzags in the graph correspond to real HR changes which also were registered by the FR955 control watch.
The final test with the rubber sleeve was along a normal out-and-back trail path containing both undulations and one (doubled) short technical section:
An: 0.1%
Ar: 0.0%
Hard to find a cleaner result. The HR graph in the Suunto App had one quick change which I at first didn’t recognise, but then remembered as an episode of: running in a slight descent towards a junction while seeing a man and a free running dog, taking the turn, hearing the man shouting ‘No, no, stop, stop’ at the dog, feeling some touching at my heels, turning torso backwards while still running, seeing the dog go to ground and wagging its tail, turning forwards again and continue the run. During this episode my HR jumped 5 beats over 10 seconds:
The FR955 OHR has a more smoothed graph and less change/variation:
So. I can live with this hardware hack. It shouldn’t be necessary, but… Depending on level of air dryness I’ll probably see some R-R points outside of reality at times due to electrostatic charges jumping through air to the pod surface, but the HR registered should stay sane overall.
I will report back if something changes to the worse. Think I’ll also turn on running dynamics in the pod now. Having cadence from the torso is much better than the wrist version.
To end, a picture of the ‘prophylactic’:
Suunto Race S
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I used a sleeve of inner tubing from an old bicycle tire. Cutting a small piece for the SHRM2
Looks like very effective solution
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@Inge-Nallsson I am very impressed by your not giving up and finding a workaround for you problem!
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@Inge-Nallsson Thank you very much! I´ll try your hack too
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@Inge-Nallsson That’s crazy. Thumbs up—I’m impressed. I guess no one at Suunto thought of that. Unfortunately, I decided to send the HRM2 back. I was hoping support for the Vertical 1 will come, and I also feel like the older belt fits me better after all. We’ll see what the future brings.
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@Inge-Nallsson damn, kudos! now, if insulating the module’s outer surface eliminates the noise, the coupling path would be via that surface (specs mention a stainless steel cover plate) and not via the skin.Therefore, the stated “shielding” would not protect against it, and this makes me think of a possible hw-level ESD immunity weakness or issue, hard to fix via firmware alone although Inge’s test cannot distinguish insulation from reduced shirt-module friction
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@Inge-Nallsson Great work, but honestly I don’t like to run with a rubber tube on my breast. I hope Suunto will reuse your analysis to correct the algorithm on SW side (if possible) or provides a replacement or a cap or something.
I don’t understand that a big company couldn’t do what you could do alone in a few days -
@Inge-Nallsson I’ve been spritzing the front of my shirt right in front of the module, and while it’s reduced starting noise, I’m still seeing it in the run. So I’m curious about insulators that I can use to cover the module, like perhaps electric tape or heat-shrink rubber.
The noise at the end of this run is while I was in a headwind. I’m guessing the shirt dried enough that ESD started becoming a problem again.
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All <-- Thank you for the thumbs up asf, but I was just following a logical path. Regretfully my education has been mainly within the Humanities so I have almost nothing to contribute when it comes to electrical engineering. Asking Google about alternatives to the rubber tube they listed some materials but also pointed out that static electricity has a tendency to find paths and discharge into a highly conductive steel cover plate (although measuring I find no conductivity anywhere on the pod, probably due to the coating). And looking at the construction with the push-button area I would consider that an easy path inside for discharges. For peace of mind I will continue with a rubber tube since (Google):
“Your rubber tube, on the other hand, acts as a permanent physical and dielectric barrier that doesn’t care about wind, drying times, or layer-to-layer friction. It completely isolates the pod mechanically”
It helps that I have so many years of running with rubber tubing beforehand
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Regretfully my education has been mainly within the Humanities
So, you didn’t know it couldn’t work - and that’s precisely why you came up with a working solution! Thanks a million for the excellent analysis and the solution!
Only one question remains - if Suunto dev team will get this information and what they do with it. Is there anybody able to pass the info to the dev team?
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