HR Sensor Struggled in the Cold

Discussion in 'Apple Watch' started by exxxviii, Oct 18, 2015.

  1. exxxviii macrumors 65816

    exxxviii

    Joined:
    May 20, 2015
    #1
    I did my first cold-ish run yesterday in 42 degrees. It was the first time that my AW heart rate sensor was not totally awesome. I had a long sleeve shirt on but no gloves. Almost every time I glanced at HR during the first 1.5 to 2 miles, the watch either had no reading (grayed out) or it was 30 bpm to 40 bpm too high. After the first couple miles, it was fine the rest of the way. I was wearing another optical HR sensor at the same time that was working fine over the entire run.

    I remember reading a couple other posts from people having issues with HR in the cold. This is only my first, but I wonder if it will be a common thread as we enter winter.

    I would be curious to graph the HR from the AW against my Garmin, but there is no practical way to easily extract and graph AW HR data using Apple's app stack.
     
  2. BlueMoon63 macrumors 68000

    Joined:
    Mar 30, 2015
    #2
    I may be in the same boat as you. I did a walk/run earlier this week when it was 32 outside and the Apple Watch did not have much luck and I am someone who has always had success. My Readings were all over the place. I was doing A simple walk with some sprints... nothing serious as it was too cold and all I was wearing were shorts a t-shirt and a long sleeve hoodie. Here are two attempts and what happened to me plus a treadmill walk earlier in the morning. I thought it may just be a fluke but now I don't think so and since I didn't workout long either time, it may be a temperature thing...

    Since I had the watch on all morning and under the hoodie, I wonder if it has anything to do with my body feeling the cold more than the watch?
     

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  3. Julien macrumors G3

    Julien

    Joined:
    Jun 30, 2007
    Location:
    Atlanta
    #3
    I ran twice lately in a cool rain (only about 50ºF to 55ºF) and had high HR readings problems. Last 2 runs that were not in rain where fine. Yesterday's 10.5 mile (66ºF sunny) and my Garmin 620 had an average HR of 149 and my Activity app says 149 too.
     
  4. exxxviii thread starter macrumors 65816

    exxxviii

    Joined:
    May 20, 2015
    #4
    This could suck, if the AW HR sensor cannot handle the cold. We had a great run during the spring and summer, but I run all year long.

    I just did a walk in the cold this morning. Similar results--it took about 15 minutes before HR readings became reliable. I suspect that the sensor is not robust enough when the body constricts surface blood flow during cold temperatures. Mio and others have long ago solved for this. This year I switched to a Scosche Rhythm+ for my Garmin instead of the chest strap. The Rhythm+ does not seem to care at all about temperature so far. I wonder how the FB Charge HR responds in the cold? I have a couple running buddies that use those, so I will know soon.

    I actually have come to use and depend on my AW for real-time HR during my runs. I double-wrist with a Garmin 910XT. I have my Garmin screen setup with cadence and pace info. And, I have my AW for real-time HR readings. I run by HR and cadence. If the AW goes tango uniform for HR readings in the winter, that will mess up my perfect technology universe.
     
  5. BlueMoon63 macrumors 68000

    Joined:
    Mar 30, 2015
    #5
    Let's hope that isn't the case but I bet the Fitbit works fine. I don't think that tries to read blood flow the same way apple does.

    Thankfully for me, I won't run outside in the winter and I am just a casual runner. If you are a serious runner, I wouldn't count on the Apple Watch as a serious tool. Bummer.

    The only good news was the measurements were always correct for distance for me. I can't fool the watch on the distance whether slow walking or sprints.
     
  6. BlueMoon63 macrumors 68000

    Joined:
    Mar 30, 2015
    #6
    Wanted to give an update. I saw the Apple commercial of the guy shadow-boxing and checking his Apple Watch and his watch was at least 1-1/2 inches above his wrist. Lately, when I was walking or doing HIIT, I had the watch closer to a half inch from my wrist.

    Today, it was a little warmer so I will monitor, but I moved the watch up my wrist even farther than before - closer to 1 1/2 inch above my wrist and never lost a pulse doing an interval workout in 40 degree weather.
     

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  7. gsmornot macrumors 68030

    gsmornot

    Joined:
    Sep 29, 2014
    #7
    Wonder if its moisture related. Winter is drying and maybe once you get going and sweat a bit it makes better contact. Maybe wet your wrist prior to heading out and see what happens. Should not be needed but I have to for my Garmin chest strap. My strap is electrical versus my watch using LED but guessing here just to help with the testing. I didn't compare today on my bike ride but I will try to keep it in mind for later in the week when I ride again. I will compare to my Garmin 500 bike computer and strap.
     
  8. BarracksSi macrumors 68040

    BarracksSi

    Joined:
    Jul 14, 2015
    #8
    I drew up a little diagram for a post on another forum, but don't have it on my phone to put here on MR --

    I think that I usually snug up my AW so it stays further up my wrist, likely about the same place that you tried this time. I forget the names of the pointy parts of the ends of the forearm bones, but the watch sits just proximal (closer to the body) of those points by barely an inch.

    I haven't graphed the AW's HR data with an app, but my guess is that it's been doing pretty well. I have not tried it in cold weather yet, though, but we'll see if it keeps going okay.
     
  9. BlueMoon63 macrumors 68000

    Joined:
    Mar 30, 2015
    #9
    I measured the distance just to be totally anal. The center of the watch to the "bump" or pointy part as you call it from the wrist bone was 1 3/4 inches. I wear it at this level for golfing with a snug hold and it is fantastic for keeping the heart rate steady. I tried a second time today doing only HIIT going all out for 30 seconds and walking 30 and again going all out for 10 cycles with jogging before and after and it was perfect for heart rate, distance and expected calories. I will keep trying as the temperature drops here to the low teens in the coming days.

    I can say for certain, if you wear the Apple Watch on top of the bump or loosely, you will never get a consistent heart rate no matter what the temperature is outside.
     
  10. BarracksSi macrumors 68040

    BarracksSi

    Joined:
    Jul 14, 2015
    #10
    Yup. It's like it needs to be forced to "see" the blood flow. The point about the body restricting surface blood flow in cold weather makes sense, and I'm sure it's rough for optical HR sensors if any brand.
     
  11. yiliangliu macrumors newbie

    Joined:
    Jul 17, 2010
    #11
    @BlueMoon63: My apology to ask one irrelevant question. Which app did you use to export your Workout data?
     
  12. BlueMoon63 macrumors 68000

    Joined:
    Mar 30, 2015
    #12
    Sure... It is called Exercise Pulse. Not bad for tracking workouts and to show that the apple watch is normally perfect and doesn't lose the HR :)
     

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