I’ve been using the Whoop strap now for about 6 months and it does give some interesting feedback, but sometimes I just have to FTFP.
The Whoop system will log activity and sleep automatically, which I think it is set to do by default. If not, you can turn on automatic activity detection in the iOS app by going to Settings>Activity Detection>On. Basically, an activity will automatically be generated when you “exhibit sustained, significant cardiovascular exertion for at least 15 minutes”. I find it works most of the time. After an activity is done it will show up on the screen that shows your daily strain, recovery, sleep, and system status. The activity will initially be unclassified, and you will see the ‘process now’ button. You can then select the type of activity and add the subjective comments to it.
I do find the sleep and recovery information pretty useful, although at times, if I wake up in the morning and I’m showing I’m in the red, but have a big ride scheduled, I just have to do the ride, but manage how I feel during. What I have learned from using Whoop though as I get older (now 51) is that I need a little more recovery after my big Sunday rides. Last week did 145km gravel ride, and I needed until Wed to do my next hard workout.