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Heartbeats lost after increasing BPM quite fast?

2300288
over 4 years ago

Usually the calorymetric measurement over pulse is working quite well inside absolutely acceptable limits. 

But under some condition this is getting realyy bad - What I observed:

(ME... that is a quite heavy, but well trained person: Weight abt. 110 Kilogram, running under 6 min/km over more than 10 km and I am able tu push 130kg on benchpress... I doing crossover-sports for about 25 Years. Getting a little fat last time... ;-)  )

(1) Capturing only every second (!) beat of the heart...

... after increasing heartbeat quite quick. Cycling quite chilled, 115 BPM over some dozen km - No problem: Kcal and BPM counting is good. But if there will be an extreme spring letting the pulse raise from 115 to ober 180 per minute in less than a minute the GARMIN INSTINCT TACT seems to be suspendes: Until reacing BPM under 100 again the device counts only every second (!) beat. So manual pulse measurement (counting as good as possible at this high rates...) compared to the display will show quite exact a division by 2 - Measurement will get incorrect due to this issue. 

(2) "Underperformance" Sports...

If I am on a trekking tour, wearing a heavy Backpack beneath my own weight in the mountains and GPS will measure correctly: 16km and the kcal will say: You´ve burned 600 kcal... Sorry: No way! At least this should be abt. 1500kcal or more due to severel hundreds of meter climbing and downhill and feeling extremely exhausted. (Quite easy: Over the years I´ve got a feeling for this: Eating meals with several thousands kcal on those trekking tours will effect loss of weight - So the "output" must be over "input"...) 

Trekking and walking: If the pulse stay under (quite exact) 100 BPM, the measurement beacomes quite unplausible. Is this an issue of the algorithm itself - Or the implementation of the algorithm (maybe the principle of measurement?) inside the Instinct Tact?

To simplify - Again the two issues I have examined: 

First: If there is very quick raise of BPM, the Instinct Tact starts counting only every 2nd beat which will lead into wrong result of kcal and wrong pulse logging, too. 

Second: If there are low-performance sports which will have a long duration of hours under a pulse of (quite exact) 100 - The calorimetrical results leaving acceptable tolerance. (Counting will be min. factor of 2 under plausible results.) 

Maybe somebody else detected this two issues. Mostly the watch works well... but in some cases the measurements seems to be inacceptable wrong. This is not a really big thing, but annoying anyway. 

Top Replies

  • over 4 years ago +1 verified
    2300288 said:
    Trekking over hours in the mountains will "cost" more than 600 kcal by sure. 

    If the HRM is not accurate, the Calories calculation cannot be, either. However, besides entering your…

All Replies

  • 0 over 4 years ago

    For 1) You will have to use a heart rate strap in order to get more accurate results, for 2) I think calories count algorithm is based on body weight and heart rate but in your case it will not account the weight of the backpack.

  • 0 over 4 years ago
    darnich said:
    I think calories count algorithm is based on body weight and heart rate but in your case it will not account the weight of the backpack.

    It will, since the weight of the backpack will trigger higher HR, and lower HRV. Both of them influence the Calories calculation.

  • 0 over 4 years ago

    Thank you for quick response. 

    But I don´t agree with you: 

    Even without the weight of the backpack I am 110 kg - Trekking over hours in the mountains will "cost" more than 600 kcal by sure. 

    On the other hand: I´ve choosen a new watch to log my heartbeat, because due to an "happening"... well: To shorten wearing a wrest-belt is no alternative for me. 

    There are some issues and I am not really angry about them: I just want to find out the reasons why and I did a lot of investigations wirh the Instinct: 
    There is a bug in counting kcal under 100 BPM and if you raise the pulse very quick, the issue of dropping every 2nd heartbeat is annoying. 
    Nothing about life or dead - Sure! But interesting to investigate and if there is a "bugfix" (depends on: This may be a bug, or not? Who knows?). 

  • 0 over 4 years ago

    As for the accuracy of the OHRM, have a look at this doument: The Heart Rate Sensor on My Garmin Watch Is Not Accurate

    Personally, for me, the HRM works reasonably well, even under high load (~180 bpm), as well as at rest, but there are people for whom it does not work even al relatively low load. It all depends on the physiology, the fit, and many other factors. Some of them you can influence, others you can't. If you do not manage getting it better, using the tips in the document, a chest belt as  suggested, is the solution.

  • +1 over 4 years ago
    2300288 said:
    Trekking over hours in the mountains will "cost" more than 600 kcal by sure. 

    If the HRM is not accurate, the Calories calculation cannot be, either. However, besides entering your true body data into the User Settings, make sure you correctly adjsuted also the "Activity Level" option - it has a great influence on the Calories calculation too.

  • 0 over 4 years ago in reply to trux

    This is a very useful suggestion!

    I will try to read more about this and maybe this will be the "tuning" I need to make measurement more accurate in lower BPM stages. 

    THANK YOU!



    Maybe I didn´t recognized a "tuning" possibility for the HRM-Measurement, too?

    BTW: I am able to measure high beats, too! This is not problem, if I raise the hearbeat not as fast as described... then 180+ is no problem. But rising from low to maximum in a short time, then the loss will begin... 

  • 0 over 4 years ago in reply to trux

    I agree but there is a big difference for avg 160bpm for 75kg and 160bpm avg for 100kg over 1 hour of running. I can see it almost daily when I run with my heavier friends and we are around the same avg bpm

  • 0 over 4 years ago in reply to darnich
    darnich said:
    I agree but there is a big difference for avg 160bpm for 75kg and 160bpm avg for 100kg

    That's why the body measures and the HR Variabilty are considered too. And as for the additional weight of a backpack - I can assure you that if you try to run a with a heavy backpack, your HR will be higher, and/or the LT onset earlier, and the training stress higher (both of it detected thanks to the HRV). In the consequence, the Calories burn will be higher too, of course.

  • 0 over 4 years ago in reply to trux

    Yeah sure I never said anything contrary, however the "bodyweight" is an important parameter in the algorithm and it changes significantly when you carry a heavy backpack 

  • 0 over 4 years ago in reply to darnich
    darnich said:
    however the "bodyweight" is an important parameter

    I do not think anyone ever doubted it