Heart Rate Inaccuracies

NurseB33 said:

I'm familiar with the terms, it is because I have a medical condition that I am seeking more accurate HR numbers. 

I initially figured you were, given your username haha, but I wasn't 100% sure, because your post went from talking about average HR to (average) resting HR and back to average HR.

The thing about the "true average" (daily average HR) is that Garmin doesn't claim to calculate it at all, which is why this statement was confusing to me: "about how Garmin calculates average heart rate in the Connect app". That's why when you followed that up with "average HR on a day to day basis" and  "average resting HR", it was unclear whether you meant two separate things or one thing.

You also said this: "It’s important that I have a more accurate way to calculate my average."

But again, Garmin doesn't calculate daily average HR, and they don't claim to.

Again, what Garmin shows in Connect is:

- (1d) resting HR and high hr

- (7d) 7d average resting HR and 7d average high hr

So if you really want to know your daily average HR, I think the only way is to export the data and calculate it yourself. But this isn't exactly user friendly.

NurseB33 said:

Yes, that is what I'm seeking, a true average although I was wanting more of an accurate resting HR.

But of course the daily average HR ("true average") and resting HR are two completely different things, which is why it's confusing to me that you talk about them in the same breath, like this:

"I am trying to get a better sense of my average HR on a day to day basis. I don’t know what algorithm Garmin uses to calculate average resting HR but it appears to me wildly innacurate."

Obviously you know that "(daily) average HR" and "resting HR" are two different things, but the above quote reads like you are suggesting "average HR" and "average resting HR" are the same thing.

And to be clear, Garmin doesn't directly calculate "average resting HR". It calculates a daily resting HR (using an algorithm), and it calculates the 7d average (by taking the average of the daily resting HR for the past 7 days). The daily resting HR is not meant to be a "daily average" (regardless of the fact that the algorithm uses 30 minute averages to calculate it), it's meant to be the single resting HR for that day.

NurseB33 said:

My 66 is wildly inaccurate since it only happened once during a 30 min frame of sleeping

To be clear, if Garmin shows 66 for your resting HR, that means it was the lowest 30 minute average for the 24 hour period (as you quoted).

This doesn't mean 66 was only measured once, it means that for the entire day, Garmin calculated a rolling 30 minute average [*] for your HR, and 66 was the lowest calculated value. Your heart rate averaged 66 for an entire 30 minutes.

[*] at any given point in time, this value is the average over the last 30 minutes

Again, I realize this isn't exactly a standard way of calculating resting HR. As a layman, I can see a few problems with this:

- since Garmin takes the lowest 30 minute average during the entire 24-hour period, the value it calculates might be too low, since it includes the time when you're asleep. (As far I know, resting HR is supposed to be measured when you're awake)

- since Garmin takes a 30 minute average, maybe the value it calculates might be too high, since the standard ways of measuring resting HR involve measuring HR for a much shorter period of time?

idk, maybe those two things cancel out? I don't know the scientific basis for Garmin's algorithm, tbh. I would think it would be better if Garmin excluded HR during sleep, but what do I know?

I am curious what algorithm you think would be better. It's also not clear to me whether you think 66 is too high or too low for you.

Since you mentioned "iwatch" (I assume you mean Apple Watch), this is what Apple does:

https://support.apple.com/en-gb/120277

Apple Watch also calculates a daily resting rate and walking average by correlating background heart rate readings with accelerometer data when sufficient background readings are available.

So it looks like Apple Watch calculates resting HR by measuring your HR when you're not moving.

And someone posted this last year:

https://developer.apple.com/forums/thread/759878

Are you referring to data measured by Apple Watch?

If so then my understanding (as of iOS 17 & WatchOS 10) is:

1. Apple Watch records the users Heart Rate roughly every 4-6 minutes throughout the day when on the users wrist and not in low power mode
2. These Heart Rate readings go to 10’s per minute during a Workout
3. Apple Watch only generates one Resting Heart Rate value per day
4. This single Resting value is updated during the day if needed rather than additional values being saved to Apple Health

To answer your question on querying the data that makes up a Resting Heart Rate value, I don’t think this is specifically possible. Essentially Apple have created an algorithm which uses the raw Heart Rate data to generate the Resting Heart Rate value, this algorithm is not public to my knowledge, and it has also changed over the years (for example, it used to incorporate all HR data throughout the day, now it ignores HR measured during Sleep)

At least Apple Watch excludes HR during sleep, if this person can be believed.

But Garmin does has the advantage that it measures HR multiple times per second, 24/7, unlike Apple Watch which supposedly measures HR once every 5 seconds. (Both Garmin and Apple record HR data far less frequently)

https://www.garmin.com/en-US/blog/health/garmin-smartwatches-measure-heart-rate-every-second/

Since you did mention Apple Watch, I don't think Apple Watch records daily average HR either. It records resting HR and walking average, though.