I think that, uh, there it is.

https://www.dcrainmaker.com/2021/11/whoop-platform-review.html

They extrapolate all kinds of data from a single datapoint (heart rate) using a sensor that’s far from optimal. Think “I can tell you the weather forecast based on your heating system function” except I don’t check the system, I check the air temperature in the house. The first past (forecast) is a wild stretch, the second part (sensor placement) is a silly choice.

But the marketing is slick!

Most health trackers are dumb less you're an athlete, and if so get a Garmin.

They are notoriously bad at actually tracking your stats and are often designed to lie to you to make you feel good about yourself.

I love data, but I stopped to think about what I would actually do with the data Whoop provides. I wouldn't use Whoops workout recommendations, I wouldn't alter my training plans much off their derived metrics. I decided a far simpler watch with heart rate monitor and zone would be plenty. A monthly subscription and the amount of data shared with them were also strong disincentives. I don't need yet another company tracking me and selling my details off to who knows who.

You might be interested in this guy's reviews (sorry for the big tech link, I'm not aware that the information is available anywhere else): https://www.youtube.com/channel/UChNWxrTlmh4IRSevon1X93g "The quantified scientist". Posts a lot of videos but these kinds of devices, comparing them against each other or between versions sometimes

E.g. Whoop MG 5 vs 4 heart rate tracking: https://www.youtube.com/watch?v=9SzUDTBK-i0

I tried it and the analytics are kind of interesting but I think if you pay attention it's pretty easy to tell if you're rested or not. And it wasn't particularly good for weightlifting, It's more geared towards running and maybe cycling. It's absolutely not worth the subscription price