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questions regarding the HRM swim + forerunner 735xt

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  • questions regarding the HRM swim + forerunner 735xt

    hey guys.
    i bought a couple of days ago the forerunner 735xt and the HRM swim to go along with it for swimming activities.

    i started my first tracked swimming activity after pairing the watch with the strap and the watch stopped reporting HR data underwater as expected.
    when i finished the activity the watch said the transfer of data from the strap was finished successfully but in the Garmin connect app i couldn't see any HR data on this activity. i tried syncing it again manually and it created a second activity for the same swim.
    after a day, i logged in to the Garmin connect account on my computer and saw HR data under the swim activity. i went back to the app and saw the avg heart rate and max heart rate field are now populated and a new field called training effect with a value of 3.8

    so i got a couple of questions (sorry if its too long...):

    1. how come i dont see the full range of HR data in the app? i only see avg and max heart rate values.
    2. in the Garmin connect we site (on my computer) it only shows HR data for the first 6 min of my workout.... and the time is wrong, the HR chart is ranged from 5:15 until 5:21 when in fact i started around 7PM. is it possible the internal clock of the strap doesnt match the internal clock of the watch? if so, how can i fix this?
    3. how come this activity doesnt count towards my weekly goal of 150 intensity minutes?

    link the activity (i opened it to be public):

    again, sorry if this post is too long...
    thanks in advance for helping.

  • #2
    I'll start with the easiest question, Swimming activities simply do not count towards intensity minutes. This is just how Garmin has it programmed and I am not sure why they do it that way but they do.

    As for your other questions you should see the full range of HR data in both the app and on the website and for the entire workout. The time referenced is not 5:15 pm but is instead 5 minutes and 15 seconds into your workout so it only recorded data for 7 seconds. When I use my HRM-Swim (with a Fenix 5 but the results should be the same) I get an HR data point every second for the entire workout so it is nowhere near as smooth as your HR plot. A few things you can try:

    Is the strap tight enough. If it's not fairly snug the electrodes might not have a solid connection on your chest.and would lead to missing data.

    It sounds like you already did this, but make the HRM-Swim and your watch are connected when you hit the start button, with both still above the water. Then at the end of your swim make sure they are both out of the water and reconnected before you save the activity. I usually take the strap off and set it on the pool deck and put my wrist with the watch near it while it downloads the HR data..

    Is your Data Recording setting in the watch set to "Every Second" instead of "Smart". If it is set to smart it's possible the watch is missing data points.

    Possibly consider changing the battery in the strap. Even it it is new sometimes it can have a battery that is close to depleted in it and one of the symptoms of a low battery is intermittent or anomalous data.

    If none of these fix it it's also possible you simply have a defective HRM-Swim and then you can either return it to where you bought it for a replacement or contact Garmin support for a warranty replacement.


    • #3
      thanks for the quick reply.

      regarding the intensity minutes, so what should i do to reach that goal? does running counts? climbing stairs in order to raise your heart beat counts?

      regarding the tightness of the strap, it is tight. very tight. i was thinking it might be too tight (is it possible for the sensor to be too tight to the skin?) and the next swim i will use the longer extender to have it a bit less tight.

      i will try the thing you said about starting the workout after pairing the strap and making sure they are both outside the water (and same when finishing the workout), im not 100% sure i did it like that on the first workout.

      regarding the battery, is it possible to swap the battery on the HRM-SWIM? i thought its built in and once it died you would have to get a new strap..... i will google on that
      but regardless, dont you think its smarter to contact support before opening up the strap to change the battery? (it sounds like a thing that might void your warranty).

      regarding the data recording setting to "every second" instead of "smart" can you please help me figure out under which menu this option should be on the forerunner 735xt? i failed to find it.

      again, thanks for the time reading my long post and for your help.


      • #4
        The battery is a user replaceable part and should not void the warranty. It uses a CR2032 cell and instructions on how to do this are on page 2 of the manual here: The manual also has a few tips on using the HRM-Swim so that might be worth looking at. It's possible if you contact support they would want you to try a new battery before they replaced it, though they might agree to send you a battery. They are fairly cheap though so it's probably easier to just pick one up.

        The setting for data recording is here on the 735XT: Menu > Settings > System > Data Recording.

        I'm not sure if making sure they are connected before starting the workout makes a difference but it's something I do, in part just to make sure the strap is awake and active. Afterwards it definitely needs to be out of the water for the watch to get the data.


        • #5
          thanks a lot for the user's manual link. will definitely give it a read.

          i found the setting (which was embarrassingly easy to find. dont know how i missed that...). it was indeed set to "smart". i will give it another run with the "every second" setting and with the slightly larger extender strap to make it a bit less tight around the chest.

          when you say "make sure the strap is awake and active" how do you do that? there is no lights or vibrations on the straps itself. the watch does say "connected" under the sensors and accessories menu. but other than that, what indication do you have that the strap is "awake and active"?


          • #6
            ok so i changed the setting on the watch like you said and also adjusted the strap to be just a bit less tight on my chest while making sure i start and finish the activity when the strap and watch are connected and out of the water.

            it looks like the strap got the entire activity now and everything is fine

            thanks a lot for the help


            • #7
              jackhammer are you still having problems with the Garmin Swim or is it now working OK

              As regards intensity minutes - I find that I do get some minutes for a swim if I wear the HR strap I think this is probably related to getting minutes from an elevated HR after completeing the swim activity although I have never been able to properly reconcile this and it is a much lower allowance of minutes compared with the intensity of the activity


              • #8
                i think the strap is fine. i think i figured how to use t properly (thanks to Paul's suggestions).
                for some strange reason the HR data is not showing on the swim activity when i look at it on the app, however it does show up fine on the Garmin connect website....
                did it ever happen to you guys?
                Last edited by jackhammer; 01-08-2019, 03:20 AM.


                • #9
                  jackhammer I've never seen that with my HRM- Swim used with 920xt 935 or Fenix 5+ so not sure what the cause is may be specific to your phone. Have you tried uninstalling and reinstalling the app?


                  • #10
                    Glad you got it to work. I've also never seen that behavior where it only shows up in the web interface. I have the ios app and it shows up there. If you are using Android it could be a bug there.


                    • #11
                      i am using the new iPhone XS with the Garmin 735xt.
                      there was an update yesterday to the Garmin connect app and now it actually shows more info that it used to...
                      it used to show only the HR chart and the HR zones bars graph (except for the activities with the weird bug where it doesn't show the HR chart)
                      after the update, all the swim activities now show more info on my phone app. i can see a chart for pace, a chart for strokes, HR, swolf, HR zones...

                      so im guessing it was a bug with the previous version of the app.

                      thanks for the help guys.


                      • #12
                        jackhammer glad that its working for you now