Suunto Smart Heart Rate Belt 2

snow*

@martintrail said:

@isazi Hmm, I don’t have any service that would show me that. Once I figure it out, I’ll send it here…

e.g. Runalyze tracks that data

martintrail

@isazi

snow*

@martintrail weird! it’s perfect

martintrail

@snow Yeah, it looks like it. I think I’ll try wetting the electrodes a little more and tightening the strap a bit more. No idea…This didn’t happen with my old Suunto strap.

isazi

@martintrail cannot see where the drops come from or why zonesense is not working from this, it seems that there is no noise in the data

Tieutieu

As anyone seen yet the new belt (without sensor) somewhere ?
My old ones are starting to decline.

martintrail

@Tieutieu In my country, it’s only for the old model.

@isazi Hmm, interesting. Well, we’ll see how it goes next time.

atoponce

Well, my SHRM2 is not a week old and I’m already getting bad HR readings.

I’m wetting the electrodes (water and licking) before placing it on the chest
I do not have a hairy chest
I have oily skin
I’m a heavy sweater
I’ve tried adjusting it’s position vertically
I’ve tried rotating it slightly such that the module is left of my sternum
I rinse it and hang to dry after every use
I’ve hand washed it once with mild soap in cold water

I guess I’m wearing the strap wrong. Maybe it’s too tight? It’s snug, but not uncomfortable. I don’t know what else to do.

Sept 25 (day 2):

Yesterday (day 5):

Today (day 6):

Mff73

@atoponce
For testing, we were advised to wear it, not too tight. Maybe try to loose a bit the belt.

atoponce

@Mff73 I wonder if having oily skin creates a film under the electrodes preventing a strong conductive connection until sweat breaks through. Perhaps an alcohol wipe to degrease the skin and electrode or ultrasound gel would improve things.

martintrail

@atoponce Well, it shouldn’t be rocket science. Just put it on and go. It seems more like a FW issue to me. But we’ll see after a few more runs. I’ve never had any problems with my old Suunto HRM or my Garmin HRM.

Inge Nallsson

@martintrail said:

It seems more like a FW issue to me

I sure hope it is! My replacement unit arrives today because you guys had a good streak with other units… And talking about streaks, the last bad one you had with strong drops in the HR (and ZS pruning) visavis a perfect R-R plot, did you upload the correct run for analysis? The timeline from the SA graph is ca 38 minutes while the R-R data has a timeline of ca 27 minutes.

martintrail

@Inge-Nallsson What I know, is the R-R chart is built from the beats the strap actually sent, so when the strap loses contact, those minutes simply disappear instead of showing as a gap. About 10 minutes are missing, all in the first half of the run.

That matches the HR graph in the Suunto app: during the first 20 minutes there are flat lines and impossible drops (down to 88 bpm while climbing), which look like the watch filling in gaps. After that the HR looks natural, and ZoneSense started showing data around minute 28, roughly 10 minutes after the signal became stable.

The R-R data that did get recorded is very clean, so it’s not noise, it’s dropouts.

Inge Nallsson

@martintrail Thanks for the clarification. I’m not that at home with the workings of R-R, obviously.

atoponce

Today’s run. I first wiped my chest clean with an alcohol wipe, then applied aloe vera gel to the electrodes. Aloe vera should be a good enough water-based stand-in until my electrode-specific gel is delivered.

The first ~8 minutes are noisy in the R-R intervals plot, then it settles. Took a bathroom stop at ~18 minutes, thus the jump there. This seems to be an improvement over the previous plots, but I don’t know if that scatter in the first ~8-10 minutes is normal. Also, I’m tapering for a Saturday marathon, thus the shorter run duration. Comparing apples-to-apples in duration is probably preferred.

Regardless, the average line tells me this is largely physiology. R-R is settling while HR climbs as I warm-up. But the scatter in those first minutes tell me perhaps the contact between the strap and chest isn’t uniform, thus the artifacts. I was kind of hoping the SHRB2 artifact detection in the module would remove this, but maybe that’s looking for something different?

Inge Nallsson

Inge-Nallsson said:

I will definitely initiate a return of the SHRM2. The faith in this unit is lost and questions about the overall hardware/software interactions are raised in my mind.

Alright, a new unit arrived today and I groaned when seeing that the serial number began as “SN: 2625”, which means manufactured in week 25 of this year (middle of june) - exactly the same as the previous bad one.

I proceeded with the pairing in Suunto App (no new firmware), but this time I left everything as default. That is, I did not turn on running dynamics. My reasoning being that I didn’t want anything to possibly interfere with my main interest; good HR data.

After pairing with the Race S I turned off the optical HR option in the Running configurations, as well as the switch for running dynamics registration from the belt, minimising error paths as much as possible.

Turning the watch off and on again (yeah, computer basics) I went out and did the exact same running experiment as before: 1 km on flat asphalt (ca 5 metres Asc/Desc) in about 7 minutes. I do it as 500 metres out and then back again.

Live HR looked just like it should with a slowly rising bpm number from a normal 70-ish standing base. Saving the run, the HR graph on watch looked All OK. The Suunto App had a beautiful curve with a slight dip where I turned the run around; just as expected. I was however slightly worried about the flat section of 124 bpm neighboring the 3 minutes mark seen in the graph below:

So I went to the Runalyze site to scrutinize the R-R data. And it turned out that the 124 bpm section indeed was a period with a stable heart rate, not a loss of signal or some other anomaly. Look at these nice graphs:

Tomorrow I will do a Run/Walk session (still injured with cracked rib and ankle problems), doing 10 * 200 metres running/800 metres walking at a skiing path. A good source of Asc/Desc and HR variations over ca 1 hour 33 minutes.

Here’s hoping this SHRM2 unit will stay sound…