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Details around the HRV feature

derunti

Hi everyone, just bought a Forerunner 265 and I played around with the HRV feature with the following findings (hrv is enabled and I use the HrvMesgListener, to read out the rr-intervals in seconds):

  • With a chest strap heart rate sensor and recording a regular workout (e.g. other) I can read out the rr-intervals within the corresponding fit.file.
  • Using just the optical sensor and recording a regular workout (e.g. other) I can't read out the rr-intervals.
  • When taking a health snapshot it is regardless whether I use a chest strap heart rate sensor or just the built-in optical sensor I can't see the rr-intervals within the corresponding fit-files. Although I can see the RMSSD calculation.

Is this an expected behaviour? Hopefully not, it would be very useful if the hrv-based data (rr-intervals) will be written when using the optical sensor at least during a health snapshot (with hrv disabled, as I don't need hrv-data during a normal workout).

thx, stefan

  • 0
    derunti said:
    With a wrist-based heart rate sensor

    So this is *not* the wrist-based heart rate sensor built into the watch, but a third party sensor that is wrist-based but not optical?

    derunti said:
    Using just the optical sensor and

    And this is the built-in sensor (although it is wrist-based)?

    I am confused by what you call what...

  • 0 in reply to Etupes25

    Just updated my initial post. I mixed up chest strap with wrist based 

  • 0

    RR intervals are *not* logged using the wrist HR sensor.

    Health snapshot is a useless feature: RMSSD changes very quickly (try measuring snapshots several times after each other in normal conditions), and SDRR makes sense only by measuring for a longer period.

    Of course, if you are stressed as *** then RMSSD will be low, but that is not a useful data, because you know already that you are exhausted and that data is already available in you activity history.

    In normal conditions, however, RMSSD is affected a lot by what you've done in the last minutes, so what would you do with that data.

    Used to say that you need to measure the snapshot after waking up, in the morning, but exactly in that period your body changes extremely quickly, your sympathetic nervous system just skyrocketing, so then again, what would you do with that?

    The most useful HRV measurement could be the overnight HRV based on the SDRR, but afaik it uses the RMSSD, so that's it.

    If you are interested in real HRV analysis, you should look elsewhere, I am afraid - but no consumer level products provides that, I think. The best you can do is to record the overnight HRV with a chest strap that provides the RR data (I am not sure that you can do that with a garmin strap, unless you start an activity) and analyse that with a 3rd party tool.

  • 0

    So you're asking why rr intervals are recorded in a regular workout but not in a health snapshot? (Is so, good question!)

    The manual has a setting for recording hrv data in activities which I assume you've got turned on.

    HrvMesgListener sounds like your a developer. Is there an API contact point within Garmin listed anywhere?