Heart rate inacurate

Mavrishis5
Registered Users Posts: 2 
Apprentice Seeker

Apprentice Seeker
Hi guys
My watch is showing an incredibly inaccurate heart rate reading when running of over 180 which would kill me had it been true. Have done latest updates and reset devise as well but still no joy. Without a fairly accurate heart rate the devise is useless to me as its the main function for my needs. Any suggestions anyone? Would be grateful
My watch is showing an incredibly inaccurate heart rate reading when running of over 180 which would kill me had it been true. Have done latest updates and reset devise as well but still no joy. Without a fairly accurate heart rate the devise is useless to me as its the main function for my needs. Any suggestions anyone? Would be grateful
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Best Answer
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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.6
Answers
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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.6
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Thank you
very much for your useful and elaborate feedback which makes sense. Yes mine locks at anything between 180-190 and only on run mode which is approximately my cadence as you say. I have not tried any of your suggestions so will do now thank you very much, most useful information.0