Garmin resting heart rate calculation?

[John E]

I got the Garmin 235 recently, and overall really like it, but am completely baffled by how it calculates resting heart rate.

For example, in the last week it has ranged from 40 to 70, neither of which is believable.  When I used to check my HR in the morning with sweet beat it was generally centered around 52 or so, with 48 to 58 being a normal range.  In any event 30 beats is way too large of a range.

Also, as I'm sitting hear typing, it says my HR is about 60, but says my resting heart rate for today is 68?!?

Obviously I'm just ignoring Garmin's estimated RHR at this point but curious if you all have experience with this.  Or theories about how it's supposed to work.  As best I can tell the HR readings themselves are fine, just doesn't make sense how the RHR is derived from the readings during the day. 

[John E]

Here's a good article related to 24/7 HRM by DC Rainmaker although it doesn't shed any light on my particular issue.

http://www.dcrainmaker.com/2016/02/understanding-continual-optical.html

In fact, he actually suggests you can calculate a RHR just by looking at a minimum from the dail HR graph, but whatever Garmin is doing is estimating my RHR well above that.

[Sean Gavor]

I think it usually takes them 2-3 generations before they usually get their "new feature" figured out.

See the HRM strap, elevation accuracy, accelerometer for examples...

I also think I'm usually running faster than it says I am but I don't think that's them ;)

[Sean Butler]

The way fitbit does optical RHR is to see how your HR reacts outside of exercise, but it does not reflect your lowest HR while sleeping.  I'm not the biggest fan of this method, but maybe Garmin is doing something similar.  My lowest at night is low 40's but RHR shows up as 48-52 on Fitbit.  :-/

Optical HRV will likely show up in the next year or so.  If it's accurate, that would be great.  I'm often too lazy to do a manual HRV reading in the mornings!

/Sean

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[John E]

On Wednesday, May 11, 2016 at 4:31:59 AM UTC-4, Sean Gavor wrote:

I think it usually takes them 2-3 generations before they usually get their "new feature" figured out.

Ha, I'll try to be patient!  Garmin software definitely has improved slowly bud steadily.

Also realized that what my watch says for RHR is different than what the smartphone app says.  It's hard to tell exactly how different as they report RHR in different ways (different graphs, different averaging periods), but the app seems to do some smoothing and overall be more reasonable.

 

[John E]

The way fitbit does optical RHR is to see how your HR reacts outside of exercise, but it does not reflect your lowest HR while sleeping.  I'm not the biggest fan of this method, but maybe Garmin is doing something similar.  My lowest at night is low 40's but RHR shows up as 48-52 on Fitbit.  :-/

Yeah, based on the DC Rainmaker article I linked to above, I don't see why the RHR couldn't just be calculated as the minimum RHR during the day, throwing out any outlier data (i.e. take a minimum HR that you held for 20 seconds and isn't inconsistent with your other data during the day).

But clearly it's not doing anything like that for me on a day like yesterday because my HR was lower than Garmin's estimate of RHR for most of the day when I was just sitting down.

[John E]

Although I ought to just ignore the daily HR and RHR estimate, I'm just OCD enough to keep paying attention, and think I have sort of figured it out.

The interesting thing is that I notice my RHR can vary a bit at different times of the day.  E.g. sitting at my desk some morning it might hover around 65 but later in the afternoon it might hover around 58.  So I'm a little surprised how much my RHR can vary during the day, but in retrospect it makes sense (hydration, stress, circadian rhythms, etc.).

Any, it seems that what Garmin calls my daily RHR is essentially the highest of the RHRs during the day.  In scientific babble it's the global (daily) maximum of a bunch of local minimums during the day.  Hence not surprising that it would vary by a lot from day to day and also look much different than RHR before getting out of bed.