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Compare OHR and chest strap HR values of an activity in Garmin Connect

Ralf_23
over 5 years ago

Now the DataField “Auxiliary Heart Rate” is available in the Forerunner 945 Garmin Connect Store.

The data field write in the fit file. “Heart Rate” contain the OHR and “Auxiliary Heart Rate” the chest strap. For all the statistics from an activity like Training Effect, Training Load, Training Focus, Recovery Time, … I would prefer the opposite but this seems to be not possible for the developer.

After opening the activity in Garmin Connect I can do now an overlap of “Heart Rate” and “Auxiliary Heart Rate”.

Especially for cycling it looks very bad for me. That was already clear for me, but now I have the real data.

Now I can also try to improve how I wear my watch to get less differences. Any hints?

What is your experience? Can I trust at minimum the resting heart rate I get in the morning, or is even this OHR value wrong?

  • 0 over 5 years ago in reply to FlipStone

    Same. Was fine for easy runs wen first released. Now it reads way too high and I need to wear a HRM RUN for every run to not screw the stats up. Very disappointing. 

  • 0 over 5 years ago

    Now the 3. biking activity capture, with correct y-axis scaling in Garmin Connect.

    I had my watch on the left hand, like in my first posted bike activity. During the very bad second bike activity I had the watch on my right hand.

    During this bike activity I looked more on my watch screen and sometimes reacted according to the values. I think this times I understood something (see chart and explanation in the attached picture)

    Some further observations I made:

    1) My feeling is, when the HR difference to chest strap (real HR) was <10bpm the OHR can capture up in the next 30s.

    2) I made the observation that irregularities/potholes from the street are transferred as shocks to the handlebars and my arm with the watch. This shocks change the heart rate of the OHR sensor (not the HR of the chest strap). Then the change of the OHR heart rate is >10bpm to chest strap (real HR) the OHR get lost.

    3) It seems that the OHR values are much better than taking the hand with the watch away from the handlebar. I will check that in the next time. This can not be a final solution, but it can confirm point 2).

    4) When irregularities/potholes on the street coincide with changing heart rate (due to fast increasing intensity) the OHR sensor will loose the heart rate.

  • 0 over 5 years ago

    Since my last post I have done 4 more biking activities. The OHR Sensor was very bad (like my second post from the ride). I do not attach them because the the Y-Axis scaling of the 2 sensors was different.

    During the activities I tried several things:

    • Changing the how tight I make the bracelet of the watch has an effect. I tried everything from comfortable (but still mark from the OHR on the arm) to very tight (strong marks from the bracelet on my arm). I thing that I have found an optimal tightness between comfortable and very tight. But also with this “optimal tightness of the bracelet” I did not get good results.

    • Take the arm from the handlebars has a positive effect. Than the two values are close together the OHR follows better chest strap. But than the difference is 20-30bpm it has no effect. It also saw that a goof OHR get lost even when my arm is in the air. → No solution

    • The OHR seems to have huge problems when I cycle with low HR (75-85bpm). The OHR always show 110-120. The OHR does not like when I cycle below the HR training zones. The OHR stays 30bpm above my real heart rate and is not able to catch up. When I increase the intensity and my HR than the OHR increase his value too. So I can even not help the OHR to catch up.

    • I have the impression that the OHR make a correlation between my speed and the OHR HR. When I cycle above 30km/h he expect that I have an HR of more than 120bpm. But when I cycle downhill, wind from the back or support when using a Speed-Pedelec (support till 45km/h) I’m not able to bring the OHR below 100bpm. Even when my real HR is 75-90pbm.

    • I read once again the chapter “Wrist-based Heart Rate” page 9 of the 945 owner manual. I have done all that except the point: “For more accurate heart rate readings, the device should not move while running or exercising.” I think I reduce the movement with a good tightness of the bracelet, but I can not avoid the shocks from the street.

    Conclusion after 8 biking activities and close look on the watch screen with Polar H10 and the OHR.

    If I’m interested in a correct HR and correct metrics (TE Aerob, Anerob, Trainig Load, Training status, Trainings balance, recovery time) I have to wear a chest strap during biking activity.

  • 0 over 5 years ago

    Today I post my first running activity.

    It shows much better OHR results as for cycling.

    So with a steady state Run I can confirm the result of domengo (“Crescendo Run” for the Garmin Half Marathon Coach Program of Greg).

    But I also see a situation what I have seen during cycling. In running activities the OHR seems to expect your HR values in the HR training zones. The OHR has a problem when it is below.

    Additionally it seems that in the beginning my pace was to fast for my real HR (I was very recovered, but the watch expect from my stats a higher HR at that speed) so the OHR was searching at a higher level for my HR. The OHR only catched up after 10min.

  • 0 over 5 years ago

    I just found a Garmin explanation for the problems of the OHR at the beginning of a running/biking session. I think is is more correct than my hypotheses above.

    https://support.garmin.com/en-US/?faq=xQwjQjzUew4BF1GYcusE59&productID=621922&searchQuery=optical%20heart%20rate%20monitor&tab=topics

  • 0 over 5 years ago

    Today my result of the “Intervall Run” for the Garmin Half Marathon Coach Program of Greg.

    Even than wrist OHR is not so bad for a normal running activity you can clearly see that the wrist OHR is not so good at the start (normal), but even worse at the intervals. The Polar H10 chest strap follow smoothly my real intensity at the intervals and the OHR was lost. Even than the Y-Axis is by 1-2 bpm not the same, the OHR was not good at the intervals.

    → For correct HR & Firstbeat Metrics the chest strap is needed!

  • 0 over 4 years ago

    Hi, is there a way to check in garmin connect the heart rate source used? since iam having permannet drops in the HR connection, now i dont know if the source was the HR, the OHR or both. I know that pop up message " external HR connection"  but dont care or paying much attetntion when iam doing and focusing im my workouts.

    thanks a lot.