Garmin

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larkim Aug 2022 10:44am, 22 Aug 2022 18,756 posts	larkim Agree with Badger's sentiments I think - the absolutely flat HR looks "wrong" and it wouldn't surprise me if Garmin ignores periods when it thinks the HR is wrong like that. Mine never looks like that overnight, there's always at least 1 or 2 bpm variation in there.
Dvorak Aug 2022 10:44am, 22 Aug 2022 25,824 posts	Dvorak The graph is two minute chunks so I could be having micro-variations within that eg 48-52, averaged out to 50. But when im just sat, fairly sure its not zinging about.
larkim Aug 2022 11:04am, 22 Aug 2022 18,757 posts	larkim But at the very least if it is averaging a 2 minute period you'd expect a decimal or two in there and not a perfectly flat line. Or at least that some two minute periods you'd have 49-52, some 48-52, some 48-51, some 48-53 etc etc. I've tried to extract the raw data from the page source but it's not immediately obvious how to parse it into something human readable (better minds than mine will do it easily I'd guess), but any time Garmin displays a straight line on any graph I assume it's duff data!
larkim Aug 2022 1:57pm, 22 Aug 2022 18,761 posts	larkim Question I've been meaning to ask for a while. "Stress" is normally a HRV measure, isn't it? And that's normally the preserve of chest straps. So how does my 645 give me a stress score? Is it measuring HRV using optical (roughly)?
Kieren Aug 2022 2:14pm, 22 Aug 2022 4,424 posts	Kieren Yeah, optical is good enough for HRV. Chest strap is ideal. I use HRV4Training with my garmin 245 optical sensor. Previously I was using it with Samsung Galaxy phone built in heart rate camera / light but that awkward to hold.
Badger Aug 2022 3:03pm, 22 Aug 2022 15,520 posts	Badger HRV from optical is a lot more usable when you're still than when you're running, between motion and the much higher heart rate, so yes.
larkim Aug 2022 3:05pm, 22 Aug 2022 18,765 posts	larkim Yes, that makes sense, thanks!
Sigh Aug 2022 5:35pm, 22 Aug 2022 16,200 posts	Sigh For those thinking of upgrading, Fetch has added affiliate links to the shop for the latest watches, here: fetcheveryone.com/shop-gps.php Scroll to the bottom:
Sam Jelfs Aug 2022 9:24am, 23 Aug 2022 1,223 posts	Sam Jelfs I've tried to extract the raw data from the page source but it's not immediately obvious how to parse it into something human readable (better minds than mine will do it easily I'd guess), but any time Garmin displays a straight line on any graph I assume it's duff data! larkim you can download all the original FIT files from the heart rate daily summary page on the garmin connect web page at least. I started writing some quick python code yesterday to read and extract the useful data but didn't get time to finish anything.
larkim Aug 2022 9:30am, 23 Aug 2022 18,769 posts	larkim Aha, hadn't spotted that download option. Thanks Sam Jelfs