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Swim Pool HR wrist vs HRM TRI belt on fénix 6

teissonj
over 5 years ago

As i forgot to pair my HRM TRI before before going to swim my first time with fénix 6, It records HR with the wrist sensors.

But After the session as I had my HRM TRI on my chest, i succesfully download the HR data to my recorded swim workout.

Here the 2 results as garmin connect record the workout 2 times  (please do not comment on my poor swimming speed!)

https://connect.garmin.com/modern/activity/4459924544

https://connect.garmin.com/modern/activity/4457404768

As you can see the shape of the HR is very similar , ... however average with HR Wrist is 25bpm higher than HRM TRI

So some fine tuning of the HR Wrist firmware for swimming is expected 

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  • 0 over 5 years ago in reply to Crispin_Ellisdon

    Additionally, according to my findings, the HRM-Tri records data not only when you start an activity but anytime you put the strap on, even if it's not connected/not paired with the watch. Basically, it seems it just blindly stores all HR data marking them with a timestamp and when you select downloading HR data after the workout it matches the timestamps of the start and end of the activity and download the data between them.

    Based on that, my method is:

    - Turn off the external HRM-Tri strap on the watch, put it on and start the activity.
    - When you finished, save the activity and sync it with GC. Do not enable HRM-Tri on the watch at this point.
    - When the sync is done and you can see your workout on GC, turn on the HRM-Tri sensor, go to the activity history and select downloading the HR data.
    - When the download finished, sync your watch with GC again. You will see, that there are two identical activities on GC, the only difference is the HR data (and some metrics based on that, such as calories, training effect).
    - You can take off the strap.
    - The fit/tcx/gpx files can be exported and analyzed from both.

    I have tried this method with the Run, Walk, Other and Yoga activities, the first three are working fine, with the Yoga one though sometimes I get only one activity on GC after the second sync, I haven't yet managed to figure out why.

  • 0 over 5 years ago in reply to crt_hun

    To me, my heart rate while swimming are always 20bpm lower in comparison to HRM-Swim

  • 0 over 5 years ago


    I noticed another issue : the swim workout is recorded with a start at 06:56 , but if I opened the swim App at 06:56 I actually press the start button at 07:01.

    So HR with wrist is recorded from 06:56 but HR from HRM TRI from 07:01! but both have exactly the same duration ! I suspect that there are some timer/timestamps issue between "open the swim app" and  "start"  there.

  • 0 over 5 years ago in reply to mcalista
    mcalista said:
    that looks like the dcranalyzer

    Correct, but I have seen other fitness data analysing tools similarly defaulting to displaying the WHR data rather the HRM Tri. Analysing the raw data in a OWS or Pool Swim fit file using https://fit2tcx.runalyze.com/temp/ is interesting. It seems the WHR data is recorded in the ‘every second’ packets, along with temperature, GPS location and the like, whereas the HRM Tri data is all appended in a big lump at the end of the file. Example below from the pool swim I posted earlier:

    WHR data in with every second data packets   

    HRM Tri data ‘lumped’ at the end of the file