Bad readings from an external HRM while RUNNING and JUMPING — TomTom Community

Bad readings from an external HRM while RUNNING and JUMPING

Hi!
I have a TT Music+Cardio and I'm using a Polar H10 HRM strap to measure my HR accurately during workouts, but I have noticed the TT gives me bad readings ONLY when I'm running (no matter the mode) or jumping - it basically stops measuring HR and shows some random number between 70 and 80. If I connect the HRM to an app on my phone, the readings are always ok, hence I know it has to do something with the TT.

I've tried turning all the surrounding BTs off, resetting the HRM, resyncing and nothing.

Anyone has a different idea?

Comments

  • tfarabaughtfarabaugh Posts: 16,688
    Superusers
    It is losing signal, probably because the swing of your arms is putting the watch behind your body (or the watch could be dying). Your phone has the room for a much bigger receiver so it will hold signal better, Try factory resetting the watch but I do not really know of any other solution.
  • Filip_BorowskiFilip_Borowski Posts: 3 [Apprentice Seeker]
    Even when I run on a treadmill and the watch is directly in front of me, lying on the dashboard. Factory reset did nothing too :/
  • tfarabaughtfarabaugh Posts: 16,688
    Superusers
    Even when I run on a treadmill and the watch is directly in front of me, lying on the dashboard. Factory reset did nothing too :/

    Check the battery in your HR strap. It may be producing a weaker signal (again strong enough for a phone to get with no problem but not enough for the watch).
  • Filip_BorowskiFilip_Borowski Posts: 3 [Apprentice Seeker]
    tfarabaugh wrote: »
    Even when I run on a treadmill and the watch is directly in front of me, lying on the dashboard. Factory reset did nothing too :/

    Check the battery in your HR strap. It may be producing a weaker signal (again strong enough for a phone to get with no problem but not enough for the watch).

    Already done, multiple times, with different brands of batteries :/

    So I guess the TT is shot, probably.
  • tfarabaughtfarabaugh Posts: 16,688
    Superusers
    tfarabaugh wrote: »
    Even when I run on a treadmill and the watch is directly in front of me, lying on the dashboard. Factory reset did nothing too :/

    Check the battery in your HR strap. It may be producing a weaker signal (again strong enough for a phone to get with no problem but not enough for the watch).

    Already done, multiple times, with different brands of batteries :/

    So I guess the TT is shot, probably.

    Possibly, although I honestly have never heard of that behavior.
  • Pamir911Pamir911 Posts: 3 [Apprentice Seeker]
    On a morning jog with my pulse rate was 120 beats per min. my Runner 3 can show 150 or 170 bpm ! The average difference is 40 beats! Very bad product...
  • tfarabaughtfarabaugh Posts: 16,688
    Superusers
    Pamir911 wrote: »
    On a morning jog with my pulse rate was 120 beats per min. my Runner 3 can show 150 or 170 bpm ! The average difference is 40 beats! Very bad product...

    You can get spikes in HR due to the watch either losing the pulse signal and locking onto another signal, like cadence, or the cadence simply overpowering the pulse signal. Spikes in HR are generally from poor blood flow producing weak pulse strength, so the watch reads cadence instead. This is most common in running and is particularly apparent early in a workout or during a non-intense workout when you are not warmed up or when you are doing sprints with very high effort. You should think of the optical heart rate as an algorithm that is attempting to track a signal in a set frequency range (30-230 or whatever it uses). If the pulse signal is weak it latches onto the next strongest rhythmic signal, which is your cadence in running and the vibrations of the bike in cycling. For most people who experience this while running it spikes to around 180-200 bpm which is also the average cadence people run at. Additionally, each person has a different HR signal ‘strength’, depending on a range of factors, so some are prone to get it more than others. But usually their signal strength is lower for the first 5-10 minutes until they warm up properly. So, in that time, it is prone to latching onto cadence, which is a common fault with all optical HRs, not just TomTom unfortunately. Optical HR also can tend to lag in measurements, so if you are doing intervals it can take a but to catch up, so it shows high HR during the rest periods. If you notice it while it is happening you can try moving the watch a bit or briefly pausing your run, so it loses the cadence reading and latches back onto HR, which I find usually corrects it. I generally pause the watch, stand still for 20-30 seconds and will see it immediately start to drop. Once it gets into a more reasonable range and the pulse reading stops dithering (dithering is when it is not getting a good signal and it is a lighter grey in color) I start up again and it stays true for the rest of the run. You can also try switching wrists and the position on the wrist. I find I got better readings on my right wrist over my left and some people find they get better readings if the watch is on the inside of the wrist rather than the outside. It also helps if you warm up a bit to get your blood moving and your HR up, so it is producing a strong signal. Play around with it and see if any of this helps you. The challenge for the manufacturers of optical HRs (and this is a common issue with all brands, my Scosche also does it) is to figure out how to factor out the other "noise" that is overriding the pulse signal without also factoring out other important data.
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