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Wrist heart rate monitor WHR inaccurate

Former Member over 6 years ago

Anyone else experienced issues with the heart rate inaccuracy? My FR945's HR reading is often higher than actual by 10%-30%. Usually when walking or moving around (e.g. cooking or talking & moving hands). It is disappointing because my $200 Fitbit tracks my heart rate accurately. This is a critical feature, because many other calculations depend on it.

Resetting the sensor (with garmin's support) did not fix it.

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0 talsela over 5 years ago in reply to Woo

How is the HR (or display) stuck if it changes from 102 to 100, then to 99, then to 102 again? When it changes to 59, it's because the HRM-Run kicks in.

I'm on firmware 2.50 and sensorhub 2.20

0 Former Member over 5 years ago in reply to GarminMarathoner

Hi, I bought the 245 a few days ago and find the same thing. My resting HR is 10-20 higher than my 235 (which I know is accurate from manual checks and an ECG I had last week as part of a medical check up). The 245 is more accurate if fastened uncomfortably tightly, but it’s disappointing in that regard.

0 talsela over 5 years ago

So far my experience with the OHR in everyday life is that it's completely useless. It is wrong most of the time and has just no correlation to the activity I'm doing. When it seems to give a plausible HR and I check it against an HR strap, it's still 20-30% higher than reality about 80% of the time. Other times it's up to and sometimes above 100% higher than the actual HR.

Some examples:

I could sprint between 250m between subway trains, including sprinting up ~40 stairs, and my HR would be 70bpm when I'm on the train, even when I monitor it for minutes after. Nothing changes.
On the other hand I can lay on my couch doing nothing and see 110bpm for very long periods of time.
Sometimes when I climb the 70 steps I have to my apartment the HR doesn't pass 70, other times it can reach 100, and sometimes walking downstairs reaches 90.
Even when the OHR reading seems plausible, for example 63bpm when sitting down at the computer, switching to the HRM-Run belt shows 45-50, meaning that even when the OHR seems plausible, it's still showing 20-30% higher than reality.
Many times when sitting down with "plausible" HR, for example 55, getting up and walking around the office can make the OHR shoot to 90-110bpm. Even if all you did is walk 20 steps to get some water from the cooler

I have tried to wear the watch in three different notch settings, and on either wrists - no difference at all between the different options.

Former Member I would still really appreciate your take on this.

0 talsela over 5 years ago

With help from a ConnectIQ app and some members of this forum I was able to plot OHR and Strap-HR side by side, during about 35 minutes of just being around the house on a Saturday. The results aren't good, although I've seen much worse.

Until (1), I was just sitting at my computer and hardly moving. OHR behaves quite well.

(1) I get up and do very light activities around the house - putting away some wash in the closet, etc. OHR jumps high, and also takes a long time to reach real resting HR once I'm sitting back down.

The glitch in between (1) and (2) on HRM-Run was when the watch suddenly lost connection to the strap, so that can be disregarded.

(2) The same kind of house chores, although I'm not quite sure exactly when they ended so I didn't add the black lines. OHR is totally off anyway, and totally unsure why it jumped a 2nd time.

(3) walked downstairs, about 75 stairs. OHR jumps too high, and also doesn't cool down as I just stood completely still leaning on a wall at the entrance level.

(4) Walked back upstairs. OHR picked this one up (this time) very well, albeit with a constant 20 second delay. Notice how the OHR reported something quite similar upon walking downstairs to walking up them.

Like I said, I've seen much worse behavior than this in every day life (although I find this is already bad) and I will try to wear the strap on a full day and see what results I get. As I said, sometimes walking up these stairs results in zero change in HR (can be as low as 55).

0 Former Member over 5 years ago in reply to talsela

It's obvious you've conducted a well thought out test, but it's important to know your results are user specific and not something all users should expect. The sensor and software Garmin uses is only part of the equation. The oHRM's accuracy will also depend on how the watch is worn, where it is worn on the wrist, skin complexion, body hair, perspiration, movement of the arm or movement of the watch when worn, activity being performed, gripping an object, etc... If you had nine others mimicking your movements during the test, you'd most likely have 10 different test results. The oHRM works well for some and poorly for others. Personally it doesn't work well for me, though the 945 seems a little better then my 935. I'll only use readings while sleeping or sitting around. Everything else I take with a grain of salt.

https://support.garmin.com/en-US/?faq=xQwjQjzUew4BF1GYcusE59&productID=621922&searchQuery=optical%20heart%20rate%20monitor&tab=topics

0 talsela over 5 years ago in reply to Former Member

Actually this wasn't a well thought out test. What I want to do it wear the watch an entire day at the office and see how OHR does vs. HRM-Run, while lapping at the start and stop of "activities" (anything other than sitting at my computer). This was actually just a dry run.

The sensor and software are definitely only a part of the equation, but the way I wear my watch, my skin complexion, body hair, perspiration, and other things you've mentioned - haven't changed between my usage of the 645M and the 945 (the way I wear it might be a tad different due to the bigger form factor but from what I can tell that's a negligible difference). The only variables which really did change are the sensor/software.

I really do wonder what results people would have doing what I did while plotting both from the OHR and the HRM-Run. I don't see that I'm the only person complaining about the OHR.

For me, the OHR is almost completely useless - some error is fine- sure, but not when the error is 20%-100%. The only time it's always "right" is when sleeping. I sometimes get 20 minutes of 110bpm while chilling on the couch. These are things that didn't happen with the 645M.

I think that dismissing the issues by saying that the person is the problem shouldn't be the way to go for Garmin. Also, I see that there's a new posted thread about OHR accuracy created by Garmin - unless I misunderstood something.

I read your link. While I used to wear the watch a bit too tight in the past, I don't anymore - and based on the description on that link I wear it just right, but that hadn't made any difference.

0 Former Member over 5 years ago in reply to talsela

talsela said:

I think that dismissing the issues by saying that the person is the problem shouldn't be the way to go for Garmin.

I'm not insinuating that at all. I was just saying the oHRM works well for some and poorly for others due to the many factors. I also wasn't aware you were comparing your 945 sensor to your 645. My bad. I guess I needed to read the post more thoroughly.

0 Peter Hand over 5 years ago in reply to Peter Hand

I haven't done any rigorous tests, but the average OHR seems to have improved, perhaps due to firmware updates, at least to the point that it isn't useless. I am now on 2.70. I will have to dig into it in a more formal way, though. The ratings of "load" compared to my experience of effort don't line up. I ran a marathon yesterday, and it was one of my easiest races ever. It was over 20 minutes faster than the watch estimated I would run. So either the OHR was again too high or the watch's estimate of my max HR is way off. I'll look around on the forum for any ways to use the watch itself to calibrate to a better max HR.

0 robsy45 over 5 years ago

I have crazy readings on mine - when i do activity. On one of my runs i took my watch off becuase it said i was 100% HR. I put it back on a minute later and i was in zone 1. All over the place for me.

0 LoreRoc over 5 years ago in reply to robsy45

I have the same issue :(