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Wrist heart rate very inaccurate in cold weather

Former Member
Former Member over 6 years ago
Hi all,

First cold weather since having my Garmin 935 and my heart rate measured via the wrist sensor is very far off, it registers very high heart rates. Instead of an average around 140 I'm facing 160 bpm and more.

I remember when the wrist hr sensor concept was introduced the inaccuracy was one of the cons of this kind of HR measuring when operating in cold weather.
I was one of the early adaptors of this kind of technology when having the Adidas Smart Run based on Mio technology in 2014.
However I'm a little bit disappointed the technology integrated in the 935 anno 2018 is far worse.

As I use the 935 for steering my training programma based on my measured HR and the watch predictions on how and when to run I'm a little bit lost and very disappointed to say it friendly.
I don't think there is a hardware fault or scratches on the sensor...

Anyone else experiencing this malfunctioning of the watch when running in cold weather?

I also noticed that the speed of variation (heart rate increase/drop when changing running intensity) is far less accurate than when measuring with the classic heart rate strap.

I wondering if the latest Polar Vantage having 4 leds instead of 3 on the Garmin makes better measurements.

The wrist heart rate is a very nice feature (user friendly to wear) if it works fine, but I doubt this strongly.

Best regards,
Frank
  • 0 over 6 years ago
    This is fairly standard, and I would even say 'expected'. I sometimes get similar even with a wahoo tickr fit on my bicep - its just a drawback of OHR.
    As someone else has suggested - the high HR will be due to a cadence lock. You can try adjusting the watch to try and get it to 'recapture' the heart rate, and wearing the watch a little tighter.
    (I've come from Mio link, to scosche rhythm to Tickr.)
  • 0 over 6 years ago
    Yes, the colder it is the worse it gets, restricted blood flow as mentioned above. I for one am tired of second guessing the Wrist oHR so I use te HRM-run strap when training and a cheap bicep OHR (RunAR for $25) during races as I find it less distracting (no slippage risk for a start) and it actually does better with heavy sweat than the chest strap that can get confused.

    If need be the RunAR can be restarted with a quick on/off to set it straight. In the summer it might require 1/2 restarts but in the winter, up to 4/5 There's no way of doing that easily with the Wrist oHR unfortunately as it might help too.
  • Former Member
    0 Former Member over 6 years ago
    Frank, you are certainly not alone. I love my 935, but it has never given me reliable OHR while running, let alone in the cold. I have tried to follow the usual advice out there on where it should sit on the wrist, how tight etc. So I just wear a HRM-tri strap. Which works very well for me.
  • 0 over 6 years ago
    Frank, you are certainly not alone. I love my 935, but it has never given me reliable OHR while running, let alone in the cold. I have tried to follow the usual advice out there on where it should sit on the wrist, how tight etc. So I just wear a HRM-tri strap. Which works very well for me.



    I wrote about how to wear any OHRM (Wrist/Bicep) in a different thread, I just don't remember where. Other than cold restricting blood flow, OHRM face way too many hindrances to make them reliable.

    ~Wearing them too loose allows ambient light to seep in which can confuse results. Some OHRM uses a yellow led to diffuse the outside light others rely on algorithmic answers to deal with this.
    ~Wearing it too tight effectively "smushes" the LED'S and they can't actually get a good bead on surface blood flow. Personal opinion here but I think this is more of a wrist OHRM problem than a BICEP one
    ~Skin color is an issue as is Tattoos. In the last year, I got a tattoo on my right bicep, and my old Rhythm + is now all over the place (which is where I used to wear it). I get a smoother (but still inaccurate) result wearing it now on my right arm
    ~Muscle flexion has always been an issue for OHRM (particularly wrist ones)
    ~High intensity--anything tends to throw OHRM out of control (again more so with wrist ones). I've always noticed anything above Z2 tends to either go walk-a-bout or locks on to some other rhythmic metric (like cadence if running)

    While there are problems with chest straps (slippage or late responding), the negatives with OHRM, in my opinion, outweigh the usefulness. I only use my OHRM as a passive gauge (all-day-tracking) and the occasional long tracked walk and have done so for half a decade now. I'd love it if they matched, beat-for-beat a chest strap in every category with none of the weaknesses, but none of them are there yet.
  • 0 over 6 years ago
    I am having very similar issues with my Vivoactive 3 Music HR monitor. Whenever my heart rate gets near 170, the watch appears to be unable to distinguish between cadence and HR and sticks at very high HR levels. For example, yesterday it showed excessive HR levels for most of my run, including almost no HR difference between my last 7 min mile hard mile and an 8.30 warm down mile. The watch is recording easy runs correctly.

    Weather has been mild this week so who knows how bad it will get once winter hits? I’m wearing the watch tight and higher up from my wrist than in day to day usage. I don’t need to track immediate HR changes for short intervals, where I know wrist HR tech can struggle, but without the ability to monitor average HR over mile splits, this watch does not allow me to track fitness and monitor my training load, which is the main reason I bought it.

    I previously used a TomTom Cardio Runner for 3 years and never encountered any of these issues so I know that wrist HR tech can absolutely work for me. It is really frustrating that Garmin can’t seem to get this right, because I like the functionality of their devices otherwise. From reading this forum it seems like a long term issue that they have done little to address, which is surprising since TomTom seemed to have this nailed 3+ years ago.
  • 0 over 4 years ago

    Hi Frank,

    I have similar issues. Yesterday I did a long run, and my heart rate just went up and up until at around 10K it was about 178, when it suddenly dropped down and I averaged 156 for the rest of the run... Cold conditions seem to have some influence, because indoors my HR sensor seems to be much more accurate

  • 0 over 2 years ago

    I have the same problem with Forerunner 45. Just today, on an easy run, my HR registered over 150 which is maxed out for my age,  whereas in the summer the same pace would put my HR at about 113.  Sometimes, on a longer run, it will start responding accurately after a while.

  • 0 over 2 years ago

    I have the same problem with Forerunner 45. Just today, on an easy run, my HR registered over 150 which is maxed out for my age,  whereas in the summer the same pace would put my HR at about 113.  Sometimes, on a longer run, it will start responding accurately after a while.

  • 0 over 2 years ago in reply to 7372936

    Yes, optical heartrate sensor is inaccurate. If it can’t find your pols pulse, it will look for an other pattern and find your cadence and use that for heartrate. If you want accurate heartrate use a cheststrap. If you just what some random numbers that are labelled heartrate, a optical sensor is fine.

    garmin marketing will tell you their next watch is super more accurate.