Everyone... "overtraining" does exist. In its extreme form its called Rhabdomyolyis. I am sure their are plenty of signs leading up to this but what they are I do not exactly know.
I'm not in either camp (overtraining exists/doesn'exist), but I have to disagree with this. Rhabdo is no sign of overtraining.
Overtraining, in the way it is defined by people, happens by fatiguing your system over time to the point where it can't recover from the constant stress anymore.
Rhabdo happens from a single session that just went way, way, way too far. Rhabdo is not a sign of overtraining, but an injury - the result of an acute incident and not something that develops over weeks or months***.
If you do a sprinting session and pull your hamstring that's an injury and not a sign of overtraining.
If you slightly overdo it in a particular session and get really bad DOMS for the next couple of days that's not a sign of overtraining either.
Rhabdo is in the same camp.
***in the context of training! There are some deseases, virus etc. that can lead to non-traumatically induced rhabdo.
s your next workout equally as good or better than the last one? If so, keep going, if not, maybe back off...
I don't think you actually look at your training like that and just simplify here, but if one follows this advice he/she will never progress.
You will always have phenomenal, good, better than average, average, below average, bad and really bad training days.
If over the course of a whole month the quality of your sessions constantly declines or you simply have more below average-to-really bad days than average-to-pheomenal days then it's time to back off, but if you back off as soon as the next or even the next 2 to 3 sessions happen to be not so good, then you'll cut yourself short big time.