About a month ago my smart trainer died and I concurrently got a job that came with 100hr 7 days workweeks, on my feet all day, at least for the first month or so.
For the entirety of that month, my workouts consisted of the following - daily 10 minutes of body weight/kettlebells and 1 fast mile on my treadmill in the morning, and a 4 mile one-waycommute w 230’ elevation change that I’ve been absolutely pinning both ways, and I got in one mtb nite (early morning) ride @ 2.5 hrs.
I also have been eating very little and poorly.
Getting 75% of my usual sleep.
I got a new smart trainer, calibrated it, and did an actual ramp test, my ftp went from 245 to 266, and I’ve also lost 8 pounds, which was all body fat, according to my scale.
Yup, unless you cross-check 2 smart trainers to the same exact power meter, there are no guarantees they “match”. Tolerances alone can lead to differences on par with your info above, not to mention the fact that I expect more than a few trainers don’t hit the tolerance target.
So, recognize you just got a different “tape measure” and in reality there is a high likelihood that one, the other or both were “off”. This is common for people that swap or add power measuring devices as a perfect match is more rare than common IME.
Agree with the others, compare your trainers using a third powermeter on your bike against both.
In case both measure equal (which they very likely do not) I would explain you experience by your body being in high stress/panic mode, providing you with extra performance to allow you to fight your way out of it, i.e. so you can hunt for food, fight off enemies and then sleep.
I have experienced similar multiple times, e.g. setting unexpected PRs after high stress days with terrible sleep.
If that’s the case, be aware that this is not your ticket to a race winning season, but that you are rather digging yourself in a hole. And once your hormonal status returns to baseline your body will ask you for payback big time.
so that’s weird.