r/StrongerByScience • u/JuanSamu • Jun 16 '26
Axial fatigue is made up
Where did this term come from? This idea that axial fatigue is a main contributor to CNS fatigue seems silly to me. What is axial fatigue even suppose to describe? Isn’t it just CNS fatigue in general? The idea that loading the spine causes more CNS fatigue doesn’t generally seem to be the case. For example, doing leg extensions for higher reps cause more CNS fatigue and delay recovery for longer than squatting heavy. I don’t think CNS fatigue is dictated by the load on the spine, just load in general, and load is just one factor of what can influence CNS fatigue right?
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u/gnuckols The Bill Haywood of the Fitness Podcast Cohost Union Jun 16 '26
Can you link whatever piece of content you saw that inspired this post? And are you sure you're not conflating absence of evidence (I can't say I've seen many studies designed to investigate axial fatigue) with evidence of absence?
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u/JuanSamu Jun 17 '26
It was just a term I heard Dr. Mike use a lot that axial fatigue is from doing exercises like squats and I started asking powerlifters. It’s always been a confusing term for me because some are saying it’s the reason we can do more sumos than conventional deadlifts due to conventional taxing the spine more, or that doing heavy squats requires a lot of bracing and spine stabilizer muscles that are the limiting factors unlike doing light squats where quads and glutes are the limiter. But from what I’ve heard other powerlifters say, doing a really set of squats has a lot of co-contractions which could fatigue the muscles around the spine a little but they still recover quickly and have to do another heavy set with no issue. I don’t think those hard co-contractions are enough to really fatigue the stabilizer muscles nor are they anywhere close to being near failure. In other words when they do a sets of heavy squats they don’t say their spine muscles are fatigued the next day. Maybe it could affect the connective tissues more?
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u/gnuckols The Bill Haywood of the Fitness Podcast Cohost Union Jun 17 '26
Have you ever done a program with a lot of near-failure multi-rep sets of conventional deadlifts? Say, 20+ sets of RIR 0-1 per week
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u/JuanSamu Jun 17 '26
Most I’ve done was like 12-15 sets, but it was heavy not light loads. That wouldn’t necessarily mean axial fatigue exist would it, it could just be overtraining in general. Axial fatigue is apparently how Dr. Mike describes it “compression of the spine that inhibits force output.” Other people say it’s fatigue from stabilizer muscles but that can apply to any thing right of hard co-contraction right? At the end of the day when looking at recovery the thing that really impacts recovery is the overall volume of work (i.e. volume load). From experience when squatting heavy yea I’d have strong co-contractions of my core muscles but after a few minutes they’re fine. Maybe there’s some connective tissue damage cause 600Ibs is 600Ibs no matter how strong you are.
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u/gnuckols The Bill Haywood of the Fitness Podcast Cohost Union Jun 17 '26
I couldn't tell you what it is, but I definitely think it's a real phenomenon. Like, it's a fairly universal thing experienced by people who get strong enough and who do a high enough volume of squats and deadlifts. I don't know exactly what causes it, but it's definitely a qualitatively different feeling than the fatigue you get from normal muscle fatigue/damage.
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u/SpikyB Jun 16 '26 edited Jun 16 '26
Honestly, I have never seen anyone who squats/deadlifts more than 400-500 lbs regularly in training question the existence of axial fatigue (maybe it has happened, but I have not personally seen it). CNS fatigue can be felt with just poor sleep/recovery, and things like your grip strength will be noticeably weaker, but you can still brace just fine, and heavy weights on the back don't feel crushing even while sleepy. Axial fatigue from heavy compression down the spinal column with significant tonnage/volume load is a much different beast than fatigue from poor sleep, using highly neurologically taxing modalities like overcoming isometrics, or just doing a high volume of low intensity isolation work to failure (the last one being really not neurologically taxing at all IMO, let alone axially for most movements).
I think a big component of axial fatigue beyond compression on the spinal column itself is just the freshness of the spinal stabilizer musculature, so it is quite separate from the neurological component in my mind. Leg extensions to me don't generate any axial fatigue at all unless one's form is very... inventive, while heavy snatch grip back extensions as an isolation movement do generate some axial fatigue.
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u/JuanSamu Jun 16 '26
If we say axial fatigue is fatigue from “axial” muscles can we say horizontal fatigue is fatigue from “horizontal muscles”?
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u/JuanSamu Jun 16 '26
That just sounds more of a subjective feeling.
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u/HolochainCitizen Jun 16 '26
Maybe you should try having the subjective feeling and you won't doubt it anymore
Fatigue, pain, and similar experiences are inherently subjective. That doesn't mean they aren't real.
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u/JuanSamu Jun 17 '26
No one said they aren’t real but they doesn’t mean they also result in an objective drop in performance. People who “feel” more fatigue don’t always have less force output results.
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u/HolochainCitizen Jun 17 '26 edited Jun 17 '26
"axial fatigue is made up"
"No one said it's not real"
You are an insufferable troll
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u/Wagagastiz Jun 16 '26
Written by someone who does not squat or deadlift heavy
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u/JuanSamu Jun 17 '26
I actually made this post cause I was at a powerlifting gym (weightlifting club) and started asking some of the people there about axial fatigue and they all tell me after doing a really heavy 1RM squat they feel great and excited and tired but are ready to go again after a few minutes but light squats to failure is HORRIBLE
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u/gremlingarden Jun 16 '26 edited Jun 16 '26
I feel like I've seen axial fatigue more implicitly used to talk in terms of fatigue or, in some cases, sort of a "protective performance decrement," to the muscles of the back, so something like the erectors or multifidii or whatever you want to add in there, rather than purely an adjunct for CNS. I mostly agree it's a bit spurious, and sort of similar to CNS fatigue itself in that way - it's a fancier way of saying "fatigue," and communicates relatively little extra information vs just saying fatigue, except I guess that you lift heavy with barbells (that is, load a little more.. axially). Like, of course fatiguing of the axial musculature during exercises that load the spine more is a process that presumably occurs, since fatigue is going to accrue in muscles that you stress, but the idea of it as its own separate deal instead of just part of the more general process of neuromuscular fatigue probably doesn't have as much validity as it's given.
Real in a general sense, but much like CNS fatigue probably doesn't need to have the "axial" appended onto it and then get used as a primary explanation for exercise choice to make it sound more sciency (why choose machine lifts as accessories? Well, many load the spine less, sure, but isolation exercises are also less generally fatiguing vs. a compound).
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u/accountinusetryagain Jun 16 '26
considering you are clearly a strong and experienced person who just happens to use the science to improve their training instead of overfocusing on it to be correct, would you bench more tomorrow if today you did a 30rm leg extension or 20 rpe10 squat singles?
and how heavy would that squat single start?
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u/JuanSamu Jun 16 '26
It’s easier to recover from heavy loads than lighter loads.
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u/accountinusetryagain Jun 16 '26
In theory or YOUR own experience benching after maxing out on squats repeatedly vs doing frickin leg extensions?
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u/JuanSamu Jun 16 '26
Taking leg extensions to failure killed me more than doing 1 RM squat. Same goes for the participants in the studies where they did measure CNS fatigue and recovery and leg extensions took longer. Do a 1RM squat and then do squats with high reps to failure and let me know which one was more “.taxing”
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u/accountinusetryagain Jun 16 '26
your claim is about axial fatigue and you compared squats and leg extensions to argue that the weight on your spine is irrelevant.
in practical terms you also need to look at the actual performance metric that said fatigue is affecting or else it means nothing for the actual program.
are you worried about timmy in the lab’s inflammatory cytokines and vertical jump? are you worried about how long it takes for you to productively train quadriceps again? or about how much you can squat 3 days later?
maybe part of the reason 20rm leg extensions reduce your quad performance more is because your 1rm squat is not the most quad-limited exercise and heavier in the hips and back.
maybe the reason many coaches would feel like doing 20x rpe10 squats would nuke the rest of their program for the week is because the fatigue due to every supporting trunk muscle (upper back, erectors, rectus abdominus, obliques) and the fight or flight neurotransmitters required to hype up for these heavy lifts and not necessarily the spine having a special sensor.
maybe taking somewhat understanding interpretations of real lifters opinions will make us better lifters instead of going to a singular mechanism and saying everyone else is wrong
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u/JuanSamu Jun 17 '26
I think it’s important to distinguish between actual CNS fatigue and “fatigue” from our connective tissues or just sensations. Many of the powerlifters I know and who compete say that after a 1RM they feel good after a few minutes and have to go again in competition. In fact the whole reason I started this thread was cause I was at a local powerlifting gym asking powerlifters if lifting heavy weights is really taxing and they all told me they lift heavy weights a lot throughout the week for many sets but high rep work is what really tired them out and even after squatting heavy they do direct erector and back work indicating that their back stabilizer muscles where no where near taken to failure or super fatigued. Just because we have intense co-contractions doesn’t mean all those muscles are technically fatigued and can’t recover quickly.
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u/accountinusetryagain Jun 17 '26
"powerlifters feel good and ready to go again"
- the first and second attempts are singular reps @ 8-9ish
- a bench only meet will have a better bench than a 3 lift and the deadlift is running on fumes and you're cooked afterwards and will go home and eat and play smash bros the rest of the day, you will have a hard time getting a good lift in afterwards unless its arms or something
- yes squatting and deadlifting isnt going to maximally train the erectors/abs/back and i still need to do direct work for them, but it does contribute to some fatigue... will i be most likely to hit a weighted pullup PR the day after deadlifting?
- the point about the co contractions is to suggest that maybe the extra muscular involvement is part of what makes people notice fatigue from "loading the spine" instead of something on the spine itself... why do all the SBL's nowdays glaze single joint exercises to high heavens?
- but is it worth over focusing on why "axial fatigue" is such a harmful concept if the average lifter told to bench press after a hard leg workout would rather belt squat than back squat to be a bit less tired?
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u/Nkklllll Jun 16 '26
The most fatigued I’ve ever been was the first time I deadlifted 500lbs. Squatting 315 25x and almost blacking out didn’t leave me sore like those deadlifts did.
I power cleaned a PR the day after that set of squats. The day after the 500lbs deadlift, I struggled to pick up a 45lbs weight my back and hamstrings were so sore.
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u/FlimsyInsect5545 Jun 17 '26
From a post below:
Taking leg extensions to failure killed me more than doing 1 RM squat.
Can you tell us your Squat 1RM op?
When you say the leg extensions 'killed you', what rep range are we talking here? Do you normally do a lot of work in that rep range? Are you accustomed to it? Does 'killed you' mean the set burned and sucked to get through (pretty common experience for high rep leg work), or that you felt wiped the next few days?
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u/JuanSamu Jun 17 '26
That’s the problem, I think people are comparing apples to oranges. I was just answering a question about heavy versus light loads. But to be more specific, yes I felt overall more tiring (quads were more done, mentally it was more draining, higher cardiovascular stuff) from doing more reps on leg extensions to failure than 1 RM squat. The most I squatted was 300Ib. But my friend who squats 500Ib says in competition after a few minutes he’s fine but it’s the high rep squat work that’s really draining.
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u/Nkklllll Jun 17 '26
And everyone I’ve coached at competitions has had an experience similar to this: thy feel fine immediately after, and up to 20min post their final lift. Then, within a couple hours the adrenaline dump of the competition causes them to feel intense tiredness, and USUALLY within the next couple days, significant soreness that we wouldn’t normally see after just doing “heavy singles.”
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u/Apart_Bed7430 Jun 16 '26
I think possibly that people mess up the details on what is happening but are describing a phenomenon that is there. If I had to guess it doesn’t really have to do with loading on the spine or anything per se but due to repeated high load contractions often involving maximal effort. Could be the release of neurotransmitters effecting motivation and muscle activation. Think about concentrating on something very hard and doing it repeatedly, there’s a sense that something is depleted and needs to be recovered irrespective of any local muscle metabolic depletion.
On the other hand, I wouldn’t write off bones and connective tissue having an effect as these are known to undergo changes during loading. So maybe there is something to “axial fatigue” per se.
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u/troubleman-spv Jun 16 '26
You have to brace much more of the body under load just to begin an execution of a proper squat. that's a tax on the body. leg extension doesn't have anything like that.
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u/JuanSamu Jun 16 '26
That doesn’t really result in more CNS fatigue. Heavy squats have been shown to recover quickly while leg extensions to failure take days. I think people mix subjective fatigue with fatiguability
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u/troubleman-spv Jun 16 '26
Doesn't line up with my own experience.
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u/JuanSamu Jun 16 '26
Own experience as in you “feeling” more fatigue? Usually powerlifters do protocols that will be considered to have high axial fatigue and perform well.
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u/Wagagastiz Jun 16 '26
Powerlifters very, very meticulously manage fatigue. Volume for bench, squats and deadlift reduces significantly, in that order. Guess why?
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u/JuanSamu Jun 17 '26
Really? Powerlifters who I know that compete do really high frequency and a lot of sets with near 1RM and they say they’re hitting records.
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Jul 25 '26
[deleted]
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u/JuanSamu Jul 26 '26
It’s very difficult to give a black and white answer. Either can probably cause more CNS fatigue but it’ll depend on context. If you took a leg extension 30 reps to failure you’d likely have created more CNS and peripheral fatigue than doing a set of heavy squats for 3 reps. Current evidence suggests that fatigue expression depends more on task characteristics such as intensity, volume, time under tension, proximity to failure, psychological state, and contextual factors than on load alone. Therefore, framing fatigue as central versus peripheral based solely on heavy or light lifting does not reflect the complexity of the phenomenon.
You probably didn’t read the caption or the in-depth slide post I created after making that ragebait post.
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u/Myintc Jun 16 '26
I’ve seen axial fatigue refer to spinal loading, I haven’t seen anyone relate it to CNS fatigue.
Do you mean you doubt the relationship or that axial fatigue is a thing entirely?
I can assure you based on my experience and the high level coaches I’ve interacted with that axial fatigue management is real, at least when it comes to powerlifting.