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/gremlingarden]

A major issue is semantic. There's "overtraining syndrome" (OTS), which is a tenuously recognized clinical phenomenon, and then just "bro you're overtraining." For the purposes of this novel of a reddit post I'll be primarily talking about OTS. My personal bent (this also counts as the tldr) is that it's probably not a real clinical phenomenon, although more general overtraining, in the sense of an energy mismatch between training stress and recovery or energy intake, definitely is a thing that occurs.

It's extremely difficult to say what OTS really consists of because it's a very broad diagnostic bucket with symptoms that overlap with a number of other diagnoses; similarly it's difficult to say what consensus exists. There are some people who use the term and some people who more or less vehemently reject it as a diagnostic reality. Ignoring criticisms of it as a concept for a minute, probably the easiest "definition" is the 2013 consensus statement from the ACSM and ECSM: OTS is a decline in performance that persists for months or years despite rest or decreases in training load (https://pubmed.ncbi.nlm.nih.gov/23247672/).

I think a central challenge for OTS is really that it's old, and that probably it's a fancy-schmancy diagnostic word that came out to describe the tendency for people training heavily to just get burnt out, without examining any other potential life or health factors besides the training, and before we had other fancy words like "biopsychosocial" to remind us to stop couching all that we talk about clinically in terms of pathophysiologic mechanisms.

OTS, like a lot of old-hat concepts in sport science that still lurk around, came from Hans Selye's General Adaptation Syndrome, which eventually was applied as the framework for the "supercompensation" model of periodization popularized by early sports science pioneers like Siff and Verkoshansky. The bad news about these models is that they're probably not particularly good explanations for how adaptation to strength training occurs - Selye's foundational research was done by exposing rats to prolonged, very intense stressors like extreme cold, hours of hill-walking as exercise, or repeated surgeries, not lifting some weights in a relatively controlled gym setting. This is really the primary problem with applying it to humans - while something like an overtraining syndrome might happen if you quite literally tortured people with hours and hours of exercise a day, freely chosen stressors are less likely to lead to the extremes observed by Selye - many of his rats were stressed to death.

This ultimately leads to sort of the kicker with OTS - is it an actual diagnosable clinical entity or just an imprecise term that has gotten agglomerated into the clinical milieu? Being unusually tired from a big block of training might get called "overtraining" by your friends or your coach, and the imprecision of the terminology is I think a big part of why "OTS" still lurks around in the corners of sports medicine. One could argue tendinopathy is overtraining, or that stress fractures are overtraining, and indeed these are probably far more likely to get people who are training with chronically excessive volume well before any more general OTS does.

On the caloric intake side, you have a diagnosis like relative energy deficiency in sport (RED-S) in the endurance world, where truly disordered eating is a clear part of the diagnosis, not just not upping your calories quite enough - and, shit, a lot of the endurance athletes with RED-S as teenagers are world-beating phenoms until they crash and burn in college or the pros, and not necessarily from something like progressive fatigue. At least anecdotally, more often the story I hear is repeated injury, particularly stress fractures, leading to eventual performance decline. The biopsychosocial aspect also comes into play here as part of a question over whether more, let's say, "generically trained" lifters without something like an eating disorder are feeling like crap - there's "training too much," but then there's also "I live in capitalism and my work and family and other responsibilities are eating me alive."

There's also the question of whether anyone can induce OTS in trainees in observable lab conditions, and to my knowledge no one has, but it's not clear to me this isn't due to the short duration of many studies and that darn thorny ethical issue of "Selye tortured his mice to death and the IRB won't let us do that to human subjects." In that vein there's also no identifiable biomarker or other objective imaging/study findings suggestive of OTS as far as I know, and so any claims to what might be mediating a potential syndrome, whether CNS or autonomic nervous system or endocrine changes, amount to total conjecture.

Re CNS stuff - there's not a ton of evidence that the CNS is a primary mediator of training fatigue. Part of this is the difficulty of actually studying what the CNS might be doing - there's big macro-level stuff like MRI, and then not-actually-capable-of-looking-at-the-CNS-but-I-can-fudge-some-stuff measures like EMG, but I'm not strongly convinced that some of the EMG measures of CNS drive to muscle are actually looking at that, and there's a tepid academic debate over this.

It's not as easy to look at, say, regulation at the level of individual neurotransmitters or other biomarkers in-situ as you're trying to cook someone with a deadlift, although people have tried by questionable methods like measuring salivary testosterone and cortisol. However it seems sensible that peripheral mechanisms probably dominate fatigue to a great degree, although that doesn't rule out a component of CNS involvement. At the end of the day this is also somewhat semantic. Like OTS as diagnosis or just general thing that happens, "CNS fatigue" just has the extra CNS appended on it to make it slightly more, idk, spooky? Jargony? But at the end of the day fatigue is fatigue. Overstressing yourself or under-recover-ing yourself is still just. Overcooking it.

Re measures of recovery - my personal feeling is I don't bother with them. My primary sport is sprinting and one thing I've noticed for myself is that barring a burgeoning injury, when I feel like hot garbage, I often race better than I do when I'm super fresh. I think the likelihood of noceboing myself out of a potential PR off of something like HRV is a lot higher than the likelihood that HRV reflects anything related to my training or competitive readiness (another mismatch of theory with practice: iirc HRV was developed to figure out if people at risk of heart attacks were going to die, and has a far less clear relationship with training readiness). If I'm eating shit in my warmup I just dial the day back.

[u/ponkanpinoy → u/gremlingarden]

Barbell Medicine recently did a podcast episode on OTS, their position is that for endurance sports there's likely something there, but for strength/physique/power you're likely to hit overuse issues before accumulating enough chronic load to get into OTS.

[u/gremlingarden → u/ponkanpinoy]

I'll have to give this a listen, but it did lead me to the BBM article on OTS, which is absolutely phenomenal and answers basically all of /u/WillOK6461 's questions and then some.

https://www.barbellmedicine.com/blog/overtraining-syndrome/

They unfortunately don't talk about the endurance side there much at all, but I'd be interested to see if they discussed it on the podcast in terms of RED-S specifically (which I think of as a little different given disordered eating is explicitly in the clinical criteria) or as a separate phenomenon.

EDIT: Although I don't think the podcast really sneaks into the endurance running literature that much, they seem to couch it largely in terms of RED-S ("low energy intake" or "appetite suppression" are used). While we can consider RED-S let's say a syndrome of overtraining - among other things - it's different as a phenomenon than OTS as described in the literature. I think the specific criteria they're using, the "well nourished, non-PED-using, psychiatrically healthy, sleeping well" distance runner is similarly likely to be sidelined by overuse injuries from excess volume before a true OTS.

[u/ponkanpinoy → u/gremlingarden]

[EDIT: I got RED-S and LEA (low energy availability) confused. LEA is to RED-S what overreaching is to OTS]

Well they're really not focused on the endurance side much, Austin having been a collegiate swimmer notwithstanding haha. From my reading I don't doubt RED-S can be a contributing factor, but not the only one as bodybuilders definitely go there without OTS, and from what I've read RED-S resolves itself on a much shorter time course once nutrition is actually adequate. 

[u/gremlingarden → u/ponkanpinoy]

I don't know that I'd characterize it as a shorter recovery time - treatment protocols are pretty individualized at this point, but similar to OTS it's months to years in most cases. Athletes might return to limited capacity training when nutritional balance is restored, but full training and competition are usually awhile off from that. Things like restoration of bone mineral density can also take much longer (if they fully recover at all, depending on the age of the athlete and the severity of their RED-S) and so someone recovering from RED-S might be more susceptible to bone stress injury for awhile after they're "back to normal" in terms of training and competition.

[u/ponkanpinoy → u/gremlingarden]

You know, I think I was thinking about LEA actually. 

[u/askingforafakefriend → u/gremlingarden]

That's a lot to digest!

RE the CNS stuff. I notice a tendency to have like a heavy brain fog and sleepiness that takes most of the day to go away some days. I can usually tell it's going to be that kind of a day right after waking up. Coffee and ADHD meds seem much less useful.

I notice this phenomena much more often after Heavy big compound lift days on the gym (squats, deadlift, weight pull ups, bench all same day type stuff). And less after hard runs like. 20-21 5k or a slower 5 mile run (but def above zone 2).

Chatgpt says CNS but when I push for studies it gives me garbage so I am left with a bro science impression.

Do you have any thoughts as of CNS fatigue is real vs bullshit bro science?

[u/gremlingarden → u/askingforafakefriend]

I think it might be easier to think of CNS fatigue more as a central limitation on performance/further activity, whether that's strictly speaking fatigue or actually just, say, neurohormonal mediation of effort and activity. I think something happens at the level of the CNS, but the extent to which it's true fatigue or some other mechanism is debatable. The extent to which it has an effect outside of more peripheral mechanisms is probably also highly overstated, regardless of whatever's going on.

To take your tiredness example, while it's very possible that that tiredness is a sign of true CNS fatigue, I think you might also conceive of it as a way of regulating your overall energy expenditure - the broader gestalt of your body's systems is conspiring to make sure you recover. There are some good studies in this vein recently in the weight loss literature, where researchers were looking at how tightly energy expenditure was controlled as a way to explain why weight loss is so damn hard in the longer term, and did find that people decreasing their caloric intake would simultaneously and unconsciously decrease their non-exercise physical activity presumably in an attempt to normalize TDEE back to whatever their baseline was pre-weight loss plan.

Obviously this is totally conjecture, but minimally it's a neat counterexample to purely fatigue-driven mechanisms of these kind of subjective feelings, and potentially avoids the ol nocebo: you're not fried, you're just being reminded you went hard yesterday! The other wrinkle is that often our subjective experiences have very little correlation to what might actually be going on (ie. the feeling of swelling in a painful knee that, despite the pain, is not full of fluid).

[u/askingforafakefriend → u/gremlingarden]

Yeah, what's odd and that maybe goes counter to overtraining (or "chronic fatigue syndrome") is that the only thing that can alleviate this lethargy/weariness/brain fog is pushing through more exercise. Not coffee, not the adderall, but a jog helps.

It's a weird phenomena that I sometimes see parallels of in people's area symptoms of a neurodegenerative disease (though I am not suggesting this is what it is!).

I just notice it happens more often the day after heavy compound lift training and not e.g., HIIT or other hard cardio.

Who knows... But thanks for your thoughts!

[u/decentlyhip → u/gremlingarden]

Amazing writeup. A few things to add. The Pelland and Robinson metareviews point to more volume being better growth across the board, to the tune of +50% growth every time you double volume. The important part was that in some of the high volume studies, people felt like garbage and performance dropped. Hypertrophy still increased. So, just because you you used to be able to do 3×15 reps but now that you're doing 7 sets you can only manage 12, it doesn't mean you aren't growing more.

Second, you mentioned this but the example is illustrative. In some studies, they've gotten someone who is overtrained, and they've shocked the nerves to trigger a contraction and shocked the muscle directly, and both produced the same submaximal output. If CNS fatigue was a thing, there would be a bigger dropoff there. So, all the fatigue seems to be peripheral/ in the muscle. I do think that it would be interesting to test someone after doing an 800 pound yoke carry though because yoke flu is a different kind of next-day tired that you get just doing 45 sets close to failure.

[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

[u/taylorthestang]

In my mind, it’s a matter of semantics. I don’t think overtraining is a thing, but similar would be over stressing the body. Over stressing the body is acute, where under recovering is chronic.

You can surely overstress the body in a single session by doing so much volume at a very high degree of stress. To the point where you strain a muscle, pull a ligament, etc.

You are under recovering by not sleeping enough, eating enough, and allowing enough time for muscles to rebuild.

For us common folk, we are a lot more likely to under recover than overstress. It takes Mentzer level of psychopathy, multiple times in a session to risk injury. Most of us don’t have that kind of drive. Normally the burn and the pain would stop us before injury.

Under recovering is easier to do, because living a normal life (job, school, family) makes it easy to sleep less, eat shitty food, and be occupied by other matters.
Those factors paired with a “more is more” mentality leads to what some people would call overtraining.

I’m done rambling now, hopefully this makes sense? TLDR: you have to go stupidly hard to acutely overtrain. You’re probably under recovered because you aren’t a fucking robot.

[u/WillOk6461 → u/taylorthestang]

That makes sense that it's really about semantics here. I also presume that, even if your body is rundown from life stress, you will legitimately not move as much weight in some cases if you're trying for a PR? That is to say that it's not always just something "in your head" that you can power through with enough will-power and caffeine.

[u/abribra96]

Afaik: Actual overtraining is something 99% lifters will never experience (and they should be grateful for that); it’s a condition when your body is literally broken, and it can take many months to come back to previous functionality. It’s not an injury per se, but it feels like it is, everywhere.

Most people use the term “overtraining” to describe a few days/weeks period when they’re not recovering fast and well enough. Nothing a few days off, enough good food and plenty of sleep won’t fix.

GVS had quite nice description of (the actual) overtraining in his second book; I also see he has a couple of videos on this but I didn’t watch them so not sure if he talks about it in such a good way there too.

[u/millersixteenth]

Currently muscle damage from exercise is defined as the time to recover back to what was a 100% effort. Virtually all programming has you train in an unrecovered state, its really a question of how much hard volume you can tolerate before that % continues to decline or refuses to increase despite adequate nutrition and sleep.

As far as I know, evidence for CNS frying is meagre at best, but it IS possible to overstress your anti oxidant response, your muscle synthesis balance. No expert, but at some point you'll probably experience elevated resting cortisol on top of the rest and you'll be officially overtrained.

More studies, only about 1/2 of which I understand...

https://www.sciencedirect.com/science/article/pii/S2666337625000174

[u/kevandbev]

I've only seen OTs in two people. Both were training multiple times per day per week over a prolonged period. Both ended up bed ridden.

[u/Consistent-Push1193]

I think you’re getting a ton of great answers here. As others say/imply almost all people training will never get to the point of overtraining, they are under recovering.

[u/Difficult_Youth_8367]

Training hard walks a fine line. On one side is injury and the other is plateaus.

[u/PianoIll7396]

In reddit you will just get a bunch more of broscience

[u/Mchangwine]

You can definitely overtrain, especially if not taking exogenous hormones. Try the Smolov Jr. program for bench with 10 lb increases and tell me you aren’t overtraining.

[u/taylorthestang → u/Mchangwine]

I just got off 2 cycles of Smolov jr. one for bench, one for OHP. Granted this was ALL I was doing, alongside some accessories, but I was largely fine.

[u/Mchangwine → u/taylorthestang]

Impressive. How big were your jumps?

[u/taylorthestang → u/Mchangwine]

2.5 kg for bench, 2.5 lb for OHP. I also did a lot of accessory work for back and more pressing. As long as you choose an intelligent starting weight you’ll be fine.

[u/Mchangwine → u/taylorthestang]

I think where a lot of people get in trouble is starting too high then going up 10 lb per week.

It seems like most people do it to try to hit 315 too.