Swimming with 5X and Mio Link - no heart data in GC

Former Member
Former Member
Hi Everyone,

I had a pool swim today while having my 5X connected to MioLink heart monitor wearing it next to the watch. Watch was performing flawlessly and detected all my laps accurately. It also was reporting heart rate from MioLink as I checked that watch own monitor was off. After finishing my swim I synced my watch with GC and found that my swim activity is missing heart rate data (https://connect.garmin.com/modern/activity/1655510760). Tried to look for information on the topic and found this thread on Fenix 3 (https://forums.garmin.com/archive/index.php/t-324350.html) which didn't get anywhere, although there were a lot of discussion on inaccurate measurements, technical problems of implementing this for pool swim, and Garmin desire to protect its own chest straps monitors.

Does anyone know why Garmin deliberately not saving heart rate data for pool swim activity into GC? Or maybe I am missing some settings? I really really want to believe that I just not set something right?

In the thread I mention people were saying that there is technical issues preventing heart rate data to be saved properly (like because it is laps), but I checked my daily summary page (https://connect.garmin.com/modern/daily-summary/Belarusian/2017-04-02/timeline) and I can see heart rate data during my swim (although with 2 min intervals), so I believe it is technically possible and can be done. Another argument which was given in another thread was that Garmin doesn't want to deal with inaccuracy issue which creates a lot customer support. I believe they do the same disclaimer for UltraTrac mode - which is very similar issue to this. This leaves only last argument that Garmin is trying to protect their own chest straps for swimming. I somewhat can understand that, but at the same time I think Garmin is missing some opportunity. I personally will never ever use chest strap for swimming. Period. I also know a lot of people who swim and they won't use it either. At the same time a lot of people would use wrist-based monitor and I think Garmin should make one (I believe the main problem of inaccuracy is that water changes reflection of the skin, but there are solutions to make sensor-skin attachment completely waterproofed which could solve the problem) or at least allow people to use existing third party ones.

I was literally writing Facebook post about my experience in swimming pool today planning to recommend my setup to other people and found out that heart rate data is missing from activity and now I don't even want to post it, because I am disappointed that I have to look at my daily summary page to figure out what was my heart rate during the swim..., so please someone tell me that it is fixed and I am just missing some proper settings for this? Please save the day.
  • Former Member
    0 Former Member over 8 years ago
    Could anyone share .fit file of pool swim activity with heart rate data from HRM-Swim?
  • Could anyone share .fit file of pool swim activity with heart rate data from HRM-Swim?


    Here you go:
    https://connect.garmin.com/modern/activity/1533218102

    Yeah, I know, I'm a lousy swimmer. But working hard to make progress.

    I will keep this activity public for a couple of days, and then I'll make it private again.
  • Former Member
    0 Former Member over 8 years ago
    Thank you tmk2, unfortunately I can't access .fit file from your activity, the menu doesn't give an option to download original file. Could you download it and share the file itself?

    I have investigated suggested Aux Heart Rate data field app and found that it doesn't show heart rate logged for swimming activity. Moreover, I did some more investigation and finally understood why it is not as trivial as it looks like. .fit file for pool swimming doesn't have records for each second, instead it has records for each stroke which is definitely not every second. Fortunately each stroke record has timestamp. I believe Garmin is appending heart rate data to swim records in a special way, so later they can match stroke records and heart rate data using timestamps. I am trying to understand if there is a possibility to create modified Aux Heart Rate data field which would write the data into .fit file in a such way that it would be matched to stroke records. Before asking on developers forum I would like to look what exactly is stored inside .fit file with HRM-Swim heart rate and how.

    Thanks again for your help!
  • Thank you tmk2, unfortunately I can't access .fit file from your activity, the menu doesn't give an option to download original file. Could you download it and share the file itself?


    Sure thing.


    And since I included the original fit file I made the activity in Garmin Connect private again, so if anyone is still interested, then please use the attached file.
  • Former Member
    0 Former Member over 8 years ago
    Got it. Thanks again!
  • Former Member
    0 Former Member over 8 years ago
    I just had a swim session with the F5X yesterday linked with a Mio Fuse for HR.

    As expected, I could see the HR on the watch but it was not recorded.

    However, the HR was recorded in the Open Water mode and I can see the data in GC now. I am new to the activity tracker world so it may take a while but I will try to see if it is possible to export the data from the Fuse and merge with the F5X file or something like this.

    If anybody tried this before, please let me if this is possible and if yes how...
  • I have written a simple data field to overcome this problem. I only have a Garmin Epix, which does not support writing into the FIT file by external applications, so I could not test it. I hope that it solves your problem. You just have to add this data field to your swimming activity and it writes HR data into the FIT file during the whole session.
    Give it a try, and let me know if it solves the problem:
    https://apps.garmin.com/en-US/apps/11a9036d-29f4-4582-b5fb-9077d7e40d8b



    I tried your data field on my fenix5.
    However, the heart rate was not saved to GCM, though fenix5 shows HR in real time.
  • I tried your data field on my fenix5.
    However, the heart rate was not saved to GCM, though fenix5 shows HR in real time.


    Did you use an external heart rate monitor like Mio Fuse or Mio Link? I still could not test the app in action but it is supposed to work with external heart rate monitors.
  • Did you use an external heart rate monitor like Mio Fuse or Mio Link? I still could not test the app in action but it is supposed to work with external heart rate monitors.


    Of course, yes.
    I tested with Wahoo TICKR FIT, Mio Fuse and Polar H7.
    If you want, I will send you fit file.
    I think HR data cannot be saved into fit file during the swimming activity.