[miggol]

On top of this inaccuracy in actual measurements, many fitness tracker brands invent their own metrics.

"How did you sleep?" I asked a friend who stayed over, - "I don't know" they replied as they raise their smartwatch to their face. "Pretty well, apparently! I got a sleep score of 84."

I've also heard of an acquaintance that they cancelled plans because their (Garmin™) Body Battery was too low.

Instinctively I flinch whenever people place such importance in what is essentially an arbitrary techno-horoscope. But I also find it hard to make an argument against it as long as it inspires healthy behaviour.

[macNchz]

For a long time I was sort of baffled by the (bad) level-of-fitness and restedness metrics I was getting in a couple of popular apps.

At some point I decided to figure out what the deal was with it, and I saw that their calculations were based on resting heart rate, but because I only ever wear my Garmin running watch during actual runs, it was inferring my RHR from the lowest HR it picked up before or after my run, and reporting to every connected app that mine was like 120bpm (my real RHR is more like 50bpm). Everything was seemingly happy to just accept the garbage data and plug it into their formulas to produce garbage output. Really they probably should have just told me to see a doctor if they actually believed I had a 120bpm resting heart rate!

After that I turned off all of the automated metrics—it was a big realization about how easily messed up they can get (even if you wear your watch most of the day, you might have a fairly different RHR based on whether or not you sleep with it on). I can see this exact situation causing someone a lot of undue anxiety.

[gruez]

>I've also heard of an acquaintance that they cancelled plans because their (Garmin™) Body Battery was too low.

I wouldn't take that at face value. Sounds far more likely that they already wanted to flake and needed an excuse.

[fwipsy]

Yep. I expect they were feeling tired and the smartwatch readings just confirmed it. If they really felt like coming, the readings wouldn't stop them.

[JansjoFromIkea]

> I've also heard of an acquaintance that they cancelled plans because their (Garmin™) Body Battery was too low.

This sounds like someone who just feels like they need to provide tangible evidence for their reason being "I feel terrible"

[nothercastle]

The garmin stuff kind of works as a realitive measure when most things are constant but completely break if you do something unusual like a long hike or a new cardio regiment

[hombre_fatal]

Well, sleep score still provides value to those with zero curiosity.

For everyone else, you can click into sleep score and see how much you actually slept vs think you slept which is useful data to anyone who wants to take sleep seriously.

Health wearables give you some accountability.

[eitally]

I wear my Garmin 24/7 and generally trust it. I wouldn't cancel plans because of what it said but I can definitely tell when it's showing me data that reinforces how I feel (good or bad).