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24/7 HR Sampling

philippe.berini
over 9 years ago
I thought I'll put that topic in an own thread. Many people have the perception that Garmin reduced the HR sampling frquency as of FW 3.20. And to many this topic seems very important, yet so much 24/7 HR was one of the main reasons to get that watch.

Discussion about this started in the FW 3.20 thread around here: https://forums.garmin.com/showthread.php?337137-FR235-Firmware-updates-v3-20-and-v2-30-quot-Sensor-Hub-quot-(2015-12-09)&p=770858#post770858

My last post there about this was: https://forums.garmin.com/showthread.php?337137-FR235-Firmware-updates-v3-20-and-v2-30-quot-Sensor-Hub-quot-(2015-12-09)&p=771434#post771434

I will post my upcoming findings about this topic here from now on.

The first "result" I might have found: When moving around continiously the HR is read every 10 minutes.

From the last two nights of sleep I would guess so far, that when not moving much HR is being read about twice an hour. I suppose Garmin has implemented some algorythm that reduce "time to next sample" based on movements/steps being registered.

Note that this is just what I see my watch is doing, me registering time and step count when a reading happens.

After I stopped moving around, the next reading came 20 mins later, having made 60 steps in between.


Please feel welcome to post your own findings, graphs etc about allday HR here...
  • 0 over 9 years ago
    OK. I've been doing just that. A little more than 30 mins in. I'll continue another 45 mins, check my files and let you know what results I get.


    Ok... you don't have to check your files (though would be interesting as well to see how congruent they are with the lights ). More important here, how frequent do the green lights really turn on? Just like you did before nake note of the time when it happens.

    Might be asleep by the time you finish... but will check back tomorrow for sure.

    good luck!
  • Former Member
    0 Former Member over 9 years ago
    Still inconclusive by my test. Started at 7:20PM. I moved my watch slightly every 5 minutes to trigger the green light and placed my wrist on it for a measurement for 30 mins. At 7:50 I moved my watch, but not enough to trigger the green light and waited for the next sampling. The watch did nothing for the next 45 minutes until I picked it up again. I'm still not sure how to view the files to see what was recorded in the 15 min spans. It appears the only thing that triggers a sampling with my watch other than a heart rate change is some kind of movement while resting. Maybe someone else still on 3.10/2.20 can give it a shot and see if they get different results.
  • 0 over 9 years ago
    Still inconclusive by my test. Started at 7:20PM. I moved my watch slightly every 5 minutes to trigger the green light and placed my wrist on it for a measurement for 30 mins. At 7:50 I moved my watch, but not enough to trigger the green light and waited for the next sampling. The watch did nothing for the next 45 minutes until I picked it up again. I'm still not sure how to view the files to see what was recorded in the 15 min spans. It appears the only thing that triggers a sampling with my watch other than a heart rate change is some kind of movement while resting. Maybe someone else still on 3.10/2.20 can give it a shot and see if they get different results.


    I'm going to give it a crack tomorrow as I'm still on 3.10.

    I'll email Philippe the results so he can check what it records etc.

    I'll also post up here what its behaviours are.
  • 0 over 9 years ago
    Current HR sampling rate near useless for anything but inaccurate 'historical' data

    I got my 235 a few days ago and was not really aware of the 'problem' (and it IS a problem) with the hr sampling rate. I did a cross fit workout today and wore my old Polar hr monitor and the 235. Readings from the 235 were a joke. Forget about accuracy during the actual workout (can't really compare a chest strap to an optical sensor), but during the rest periods there was a huge difference. At one point my heart rate on the polar was 141 and on the 235 it read 93. It took over a minute to get the two back in sync. I guess this is a great fitness tracker if your heart rate doesn't change much over the course of a day...but mine does. If I can't get an option for faster sampling I'm sending it back.
  • Former Member
    0 Former Member over 9 years ago
    Ok time to post my own test. I'm currently on a road trip and took advantage of a long stretch down highway 5. Put the watch on the dashboard and let the light bumps and sway of the road convince it that I was wearing it.

    Within few minutes the HRM came on and I let it read my finger. Interesting that in the first 5 minutes it came on 4 times. I wonder if the change of movement type (wrist to dashboard) made it check to see if I was going to sleep.

    Anyway, like clockwork the HRM switched on every 30 min and I let it take my pulse each time. I did this for 2 hours. After the initial 4 measurements each time it only took one.

    So for me at least it's taking data every 30 minutes. I'm on version 3.2/2.4. Also note that the RHR it claims is in line with my expectations and the HRM works well during activities. I'm pretty happy so far.
  • Former Member
    0 Former Member over 9 years ago
    I got my 235 a few days ago and was not really aware of the 'problem' (and it IS a problem) with the hr sampling rate. I did a cross fit workout today and wore my old Polar hr monitor and the 235. Readings from the 235 were a joke. Forget about accuracy during the actual workout (can't really compare a chest strap to an optical sensor), but during the rest periods there was a huge difference. At one point my heart rate on the polar was 141 and on the 235 it read 93. It took over a minute to get the two back in sync. I guess this is a great fitness tracker if your heart rate doesn't change much over the course of a day...but mine does. If I can't get an option for faster sampling I'm sending it back.


    I too wear a chest strap while working out and you'll get no argument from me that an optical HRM can't compete. Though some may be better than others, no one makes an optical HRM that'll give you readings like a chest strap while doing exercises like one would do in a cross fit workout. You'll definitely see a difference while "resting" or "recovering" between exercises, intervals, or sets. Outside of a workout, an optical HRM can have fairly accurate readings while just performing everyday activities. I believe the consensus is the FR235 does a good job at this because sampling is done based on heart rate increases and movement. The sampling we're referring to is your resting heart rate; while you're actually asleep or when you're relaxed to a point were you have little or no movement.
  • Former Member
    0 Former Member over 9 years ago
    Ok time to post my own test. I'm currently on a road trip and took advantage of a long stretch down highway 5. Put the watch on the dashboard and let the light bumps and sway of the road convince it that I was wearing it.

    Within few minutes the HRM came on and I let it read my finger. Interesting that in the first 5 minutes it came on 4 times. I wonder if the change of movement type (wrist to dashboard) made it check to see if I was going to sleep.

    Anyway, like clockwork the HRM switched on every 30 min and I let it take my pulse each time. I did this for 2 hours. After the initial 4 measurements each time it only took one.

    So for me at least it's taking data every 30 minutes. I'm on version 3.2/2.4. Also note that the RHR it claims is in line with my expectations and the HRM works well during activities. I'm pretty happy so far.


    It sounds like your test confirmed what Philippe's test results were. Now it has me wondering about my watch since movement was the only thing that triggered my sensor light. It could be I have a unit that's acting up, or maybe the difference between 3.10/2.20 and 3.20/2.30(40) is the earlier sampled based on movement and the latter on a time frame? There's another 3.10 user who going to test theirs tomorrow. Now I'm really anxious to see their results.
  • Former Member
    0 Former Member over 9 years ago
    Posted a reply about 30 mins ago and its not appeared?
  • 0 over 9 years ago
    Here's a little "trick" to try. Put your 235 into HR broadcasting mode (from the HR widget page - press and hold the up arrow to get to that menu). Overnight I got a load of values as below! Sample times range from 1 to 15 mins.

    Another interesting thing is that is says my current RHR is 36 yet the lowest recorded value overnight is 39 so is it taking more points for RHR but just not recording them all?

    HR Interval Mins
    72
    85 1
    63 3
    49 1
    0 3
    74 5
    47 3
    49 15
    42 6
    51 3
    44 2
    50 7
    46 15
    72 1
    82 1
    67 2
    46 2
    61 6
    47 1
    41 3
    41 15
    51 6
    43 2
    41 15
    41 15
    48 7
    40 3
    46 2
    40 1
    46 1
    39 6
    49 5
    43 5
    53 6
    43 1
    41 15
    47 15
    53 3
    43 2
    56 4
    46 2
    54 2
    43 2
    49 11
    43 4
    51 4
    41 1
    48 5
    42 2
    44 15
    43 15
    44 15
    50 8
    44 1
    53 13
    44 1
    59 2
    47 1
    45 15
    62 13
    44 2
    45 15
    44 15
    54 3
    48 2
    54 1
    45 2
    51 3
    44 2
    50 10
    44 3
    45 15
    54 2
    44 1
    54 6
    47 2
    46 15
    44 15
    54 8
    65 1
    48 1
    42 5
    44 15
    54 5
    46 1
    54 10
    46 1
    52 11
    45 2
    52 9
    81 9
    48 2
    55 2
    62 1
  • 0 over 9 years ago
    Interesting Tim. How did you capture those data points?