Is this based on another language?
F = Fucking MOVE your ass
C = Chill your ass
Maybe.
I came here to say almost exactly what you did.
I can work with this!
A short Internet search gave me this: "C" stands for countdown and "F" for finish. So "C" would be the time until you start your exercise. And "F" the time until you finish your set. Sounds somewhat plausible but I can't say if it really is correct...
I wish I had your research skills. Where does it even say that?
The letters may have been chosen for early, limited 7-segment display drivers, such as a hex-to-7seg decoder.
Haha I don't have any particular research skills... I asked the AI-bot of the ecosia search engine.
But as mentioned above: I am not sure if this answer is correct...
I asked ChatGPT and it said it stood for Custom (set your own timing program) and Free (workout as you wish and press a button to record the times for later use). Not a bad idea but I had told it F is for the active period and C is for the resting period, so it is obviously wrong. Another wording gave me Focus / EFfort and Cool-down / Catch your breath.
I tried the Ecosia AI chat too, pasting the post title and it replied with Focus and Catch your breath.
“F” for fitness and “C” for cooldown?
In studies, data points named with "C" are frequently "control" points
