Heart Rate Graph Misses Max

I have a desk job, and my heart rate hovers around 50 to 60 bpm most of the day. Today I carried a heavy box up a flight of stairs and checked my HR at the top and it was 131.

An hour later I looked at the graph, and the max is 110.

For the graph itself it has to average some readings to get 4 hours of bars across the screen, but is the min/max also averaged? I guess they might do that to prevent one or two erroneous readings from wiping out the real max.

I wasn't at 131 for very long but I'm surprised that doesn't show up on the graph as the max reading.

0 Former Member over 8 years ago

Happened to me just two hours ago. I was at the gym on the elliptical and had a max of 175 bpm during the exercise. The heart rate graph only shows a max of 163, wheras I can see the 175 in the recorded activity. I have been going through the all-day recorded heartrate datasets you can download as .fit files fron Garmin connect, and it seems they are averaged over integer multiples of one minute, with most readings being 1 minute apart and occasional periods of 2-5 minutes. So what you're seeing is completely normal.

0 Tangmu over 8 years ago

Thanks for confirming. I'd prefer to see a real maximum, but it's not a big deal. It may not be practical, either, because a spurious reading could result in a meaningless number.

0 Tangmu over 8 years ago

Today I played at a park with my kids, short bursts of running. I turned on an activity to get a record. The HR graph on the 5x says my HR max was 135 ft, while viewing the activity on GC shows a max of 148, which I think is closer to accurate.

So the widget on the watch doesn't give a meaningful max HR number, which is odd, since the data is there.

0 jim_m_58 over 8 years ago

The widget is showing the Hr history, where a sample is taken and saved on a regular basis. I've not checked on the f5, but on the va-hr for example, it takes a sample every 94 seconds. If the peak happens when between saved readings, it seems that it isn't shown on the widget. When recording an activity, that data is shown every second, instead of every 94 (or whatever) seconds..

0 Former Member over 8 years ago

The widget is showing the Hr history, where a sample is taken and saved on a regular basis. I've not checked on the f5, but on the va-hr for example, it takes a sample every 94 seconds. If the peak happens when between saved readings, it seems that it isn't shown on the widget. When recording an activity, that data is shown every second, instead of every 94 (or whatever) seconds..

per DCRainmaker the F5 series of watches does sample HR every 1 to 2 seconds 24 hours a day unlike older Garmins which had a variable sample rate that could extend out over long periods of time. He states that it does record up to 86,400 individual data points PER DAY on HR and none of that is "lost" and it all goes to Garmin Connect, however of course the watch nor the app can display that many points in a single graph so there is obviously some averaging going on, perhaps an average of each minute or something. That does mean that peak HRs and lowest HRs may not match what you and the watch saw, but as stated earlier thats a good thing because this technology isn't full proof yet and it might make sense to "drop" or "average" a very short term peak or valley in your recorded HR which might not be actually real.

0 Former Member over 8 years ago

As stated above - if you download the all-day-heartrate from GC, you get one value per minute. Maybe they store HR data at a higher time resolution, but they sure don't make it accessible.

0 jim_m_58 over 8 years ago

per DCRainmaker the F5 series of watches does sample HR every 1 to 2 seconds 24 hours a day unlike older Garmins which had a variable sample rate that could extend out over long periods of time. He states that it does record up to 86,400 individual data points PER DAY on HR and none of that is "lost" and it all goes to Garmin Connect, however of course the watch nor the app can display that many points in a single graph so there is obviously some averaging going on, perhaps an average of each minute or something. That does mean that peak HRs and lowest HRs may not match what you and the watch saw, but as stated earlier thats a good thing because this technology isn't full proof yet and it might make sense to "drop" or "average" a very short term peak or valley in your recorded HR which might not be actually real.

SAMPLES every couple seconds, but SAVES in History less often than that. Look at the HR widget with it's 4hr graph. Each sample is 1 pixel wide. and at the widest part of the screen means around 200+ samples. You don't see every second samples in other words. And the history used for the widget is what the FW saves. CIQ can access the exact same history.

0 Former Member over 8 years ago

SAMPLES every couple seconds, but SAVES in History less often than that. Look at the HR widget with it's 4hr graph. Each sample is 1 pixel wide. and at the widest part of the screen means around 200+ samples. You don't see every second samples in other words. And the history used for the widget is what the FW saves. CIQ can access the exact same history.

Exactly. Interestingly, even my old Fitbit Charge HR samples and also saves the data every 5-10 seconds throughout the whole day (accessible in this sampling rate only through their API, not the web dashboard). But I think for the 24 hour overview, 1 minute averages are just fine.

0 Former Member over 8 years ago

That's what I said, the graphs can't possibly show the between 43-86k data points it actually RECORDS per day (and are saved.) the graph isn't all the data Garmin keeps or uses, just what you see.

see this from DCRainmaker:

"A notable change to the Fenix 5 series is the updated optical HR sensor in relation to 24×7 monitoring. While the Fenix 3 HR had an optical sensor, and it also monitored your HR 24×7, it didn’t quite update as frequently as it could have. Sometimes it’d be every few seconds, and yet other times it’d be hours in between updates (during workouts, it was always every second). With the Fenix 5 however, the optical sensor has been reengineered to sample every 1-2 seconds.

That sampling is then uploaded along with your daily activity data to Garmin Connect. While Garmin notes that some people may not see a major improvement in the visual graphs shown on GCM for your daily heart rate, I certainly have. They noted that behind the scenes all that data is captured, but that a lesser set is shown online (logical, since you don’t really want to try and display 3,600 data points per hour, times 24 hours, on your mobile app). In any case, here’s what that looks like."

0 Former Member over 8 years ago

On Garmin Connect you can click "Export Original" in the full page heart rate graph. The zipped fit files you download only contain samples at 1-minute intervals (at best, sometimes less). This is raw data for me (they even call it original) - I do believe they sample at a higher frequency higher and then average over a minute and store it. Unless I see actual evidence for a higher storage rate (e.g. by having more datapoints in the exported datafiles), I think that's as good as it gets. Don't get me wrong - for all-day monitoring, storing the averaged data every minute is just fine. But I don't believe in a higher storage rate unless I see it.