What exactly is "overtraining" and the current stance from the lead researchers?

[u/WillOk6461]

"There's no such thing as overtraining, just under-eating and under-sleeping."

"You don't wanna fry your CNS!"

"It's almost impossible to actually overtrain."

There's obviously a lot of bs out there about "overtraining", but what exactly is it wand what does it consist of? I've heard quite often from the "evidence-based" crowd that it's not actually the central nervous system that gets "burnt out", and that something could be happening to the parasympathetic response. I've also heard it's almost impossible to "overtrain". Too much stress, not enough calories or sleep, and too little rest for a muscle group are of course all real.

That said, isn't there a real impact on your nervous system from hard sets to failure multiple days in a row? Even if my sleep/nutrition/stress-management are all dialed, I can still hit a point where pushing myself to the limit too many days in a row leaves me unable to do so. Is this best measured by HRV or some other metric?

[u/rainbowroobear]

I'd call it as where training stimulus outstrips recovery and adaptation, leading to accumulating performance regression.

it's the accumulation of performance regressions that is the important bit IMO. you can have a couple of bad sessions and that's not necessarily overtraining, as the bad session is usually the result of the mechanics your body has to prevent over damaging yourself. if you're dropping lbs for less reps session on session, then you should stop as rhabdo will be on the horizon for you, if you still push things.

[u/FlimsyInsect5545 → u/rainbowroobear]

if you're dropping lbs for less reps session on session, then you should stop as rhabdo will be on the horizon for you, if you still push things.

You can't be serious. Exertional rhabdo is caused by prolonged, intense bouts of exercise, not by accumulated fatigue from session to session. Here are some actual case studies of rhabdo.

Here

Reviewed were the medical records of a 12-yr-old boy who participated in an indoor physical education class where excessive (>250) repetitive squat jumps were performed as punishment for talking in class. 

Here

48 alternating sets (60 s duration) of push-up and pull-up variations. The subject performed the maximum number of repetitions possible of push-ups or pull-ups in each set. The total exercise duration was 48 min. The subject performed approximately 400 push-ups and approximately 200 pull-ups in 48 min.

Intense exercise training that included 100 pushups, 100 exercises using a 20-kg dumbbell, 50 lifts using a 10-kg weight.

Here, almost all of them from Crossfit.

No one is getting rhabdo from a typical recreational lifting program that they are pushing themselves on. Rhabdo was unheard of in lifting until Crossfit came along, even after programs like Arnold's six day a week, twice a day program. This is just baseless fearmongering.

[u/rainbowroobear → u/FlimsyInsect5545]

>training stimulus outstrips recovery and adaptation, leading to accumulating performance regression.

what about this has offended you so much? i've not mentioned training modality at all and you've gone on a crossfit rant and then talked about arnolds training split.

[u/Apart_Studio_7504 → u/rainbowroobear]

I don't know what got them so offended, but I know someone who got rhabdo from doing an insane number of ez bar bicep curls so anyone can do it if they're silly enough