What everybody gets wrong about CNS fatigue

You’ve probably heard people say you should be cautious with deadlifts and heavy sets of 1-5 reps,
because these things will fry your central nervous system or CNS and affect your whole body. Central
fatigue is often feared and associated with overtraining. You may have also heard that deload weeks are necessary sometimes to let the CNS recover. All of the above is based on a completely misguided understanding of what central and CNS fatigue are. Let’s look at the facts.

Chapters:
00:00 Introduction
01:23 CNS fatigue is not central in nature
03:49 What does cause central fatigue?
04:44 Does it even exist?
06:51 Summary

Reference:

#cnsfatigue #overtraining #fatigue #nervoussystem #centralnervoussystem #mennohenselmans #personaltrainer #personaltrainers #personaltraining #personaltrainerlife #personaltraineronline #personaltraineronline

[iverbrnstad]

I remember in High School taking a sports science class taught by a former world class cross country skier, he taught about overall fatigue in just this way, and how stress related to exams, relationships, family, etc. all were contributing factors to keep in check, and plan around, in order not to over train.

[willjackson]

Huge on not pushing when your body is telling you no. Less is more a lot sometimes!

[puga]

I think we should distinguish between CNS Fatigue and Systemic Fatigue. In my view, Systemic Fatigue not only includes CNS Fatigue but also joint and soft tissue pain, performance breakdown and/or psychological fatigue or a “Wanting a reset” feeling. I feel those are good indicators of when we should deload, just my 2 cents

[robdixson]

Makes perfect sense. Fatigue is at least in part a safety mechanism to keep you from damaging yourself.

[gabriels.benetti]

I'm taking one dose of pre-workout for every time Menno says fatigue in this video

[amarug]

When I do heavy compounds, like squats or legpress even, it feels like my head just "jams" at some point, long before I reach failure (or close enough to). With more isolated exercises I can bite through the pain, no matter the burn, until it physically jams. With compounds, it's so heavy that my body just seems to tell me head "no, stop", often even before it burns anywhere. It's also important to note that this only started after quite a while (1+ years) of training, when I really started gaining a lot of strength. When I was a beginner, I could push through compounds until failure. But once the weights got heavy, my head started to resist like hell. I have since stopped these exercises, I do everything in isolation. I don't care about any "specific goals", I use weightlifting like brushing my teeth: maintenance to make sure I have a shot at avoiding problems later in life.

[a_woman_who_loves_to_lift]

I am always happy and enlightened after watching your videos. Thank you, Menno, for your discussion of the difference between mental and physical fatigue and putting to rest the overused term "CNS fatigue."

[enumclaw]

Hmmm... there certainly seems to be central fatigue, unless my leg muscles being tired causes my immune system to dip and my throat to get an infection. I don't really do any endurance training, but if I resistance train hard for more than about 6 weeks and don't deload, I feel run-down and generally unwell. If I ignore this and carry on, I then start getting throat and ear infections. It's not about pushing through laziness. I would much prefer not to have to deload. It pisses me off to be honest. Feels like a week wasted - I love working out, but I feel less and less well if I carry on until I'm forced to stop by being tired and sick enough to be bed-ridden for several days. Perhaps it's not via the mechanism of CNS fatigue, I'm fine with that, but I'm not ready to believe that (resistance) overtraining syndrome doesn't exist, especially as numerous peer-reviewed studies have explored various aspects of OTS, which includes immune system suppression, etc.

[jaymills]

People use CNS FATIGUE as a proxy for overtraining or burnout from exceeding one’s bodies ability or manage stress (social, emotional, and physical). The consequence can affect the autonomic nervous system etc and have symptoms from muscles, to sleep, to fatigue, to heart rate, to neurological (light sensitivity migraines dizziness etc)

[hmq]

Excellent content. Appreciate your choice of topics and showing how the evidence supports your narration.

[zanthomson]

For anyone confused by the implications of this video: if a deload helps you lift more, feel better, and sustain gains for longer, then keep doing it. Don't worry about what's causing it. Fatigue still accumulates over time, and intelligently auto-regulating your training load based on performance will generally lead to the best results.

The physiological explanation for why fatigue occurs only matters for researchers like Menno coming up with future hypotheses to study. Maybe this will lead to discovering new training methods that are better than what we have today.

To date, there is an extremely mixed evidence-base for and against the existence of systemic / non-local muscular fatigue (NLMF). There is good reason to question the explanation of something like CNS fatigue caused by lifting heavy (as Menno has done), but there's equally good reason to question the way in which researchers have tried (and arguably failed) to measure and investigate the role of systemic fatigue thus far.

The absence of evidence is not evidence of absence. And writing off bro-science / strength & conditioning concepts that science can't explain yet has, historically, not worked out too well.

[KeithFine]

Great video, very interesting info . My client PR’d her squat on Monday and didn’t get much sleep last night. Instead of going easy on everything today, we held back on deadlifts and pushed her accessories and chest exercises with no issue.

[squattinnfottin]

This is awesome. I do have a hard time with the notion that it's simply effort fatigue though that occurs towards the end of a big workout that might make us feel overall fatigued even in muscle groups we didn't train that day.. Even if it's not CNS or neuromuscular fatigue, it seems like there would still be some bioenergetic explanation such as having less resources from which to generate ATP, and perhaps something hormonal. It's VERY hard to believe that's just mental. Thanks for the content!

[Thisispow]

Yeah I don't know man I do have my doubts.

Ever since I've trusted and been mindful of my fatigue through out my workouts I've significantly reduced injury, and improved results.

When I did not do so, and thus trained heavy consistently for many months without deload, I would stagnate and stop progressing.

I do believe that some people are better than others at accurately evaluating their true fatigue levels compared to others. And I can see how that can create a huge spectrum of people who fail to see that their mental fatigue has not much to do due to overtraining but actually due to other factors. However for myself, when I pushed on despite of intense fatigue, I only dug myself a bigger hole... With bigger injuries.

[SeuOu]

I'm on board with the idea that 'CNS fatigue' is an umbrella term with distinct components, from local neuro-muscular fatigue to overall psychological fatigue. Gym bro is going to point out that tired is tired, and nobody is going to have a great workout when their psychological fatigue makes their 6+ RIR feel like 1RIR. If you just keep training after that deadlift PR, the odds that most of it is just junk volume are pretty good.

[elhant]

What about inflammatory responce to training stress? Increased cortisol levels, a bunch of pro inflammatory cytokines that are realesed by muscles into the blood, etc. I assume if you train a lot of muscles very hard, this will have a noticable impact on your whole system that doesn't have anything to do with CNS. I think this is one of the reasons (if not the main one) why some people want to puke after multimple sets of heavy squats for example.

[AdrianMark]

I was really surprised at how well researched your video is. And I wish you had left a link to your book, it's not pushy when you have connected it so well to the subject matter of your video. Additionally, I usually buy my books through the Google Play Books store. Did a search there and couldn't find yours. Just thought I would share my search intent and method.

[KasumovMedia]

Personal anectode (would live Meno's opinion if he reads this)

Recently I kept getting stonger thru weeks 6, 7, 8 of my last block. I kept thinking "wow I guess I can continue pushing the strength"

Mid session on a hack squat i have started getting exertion headaches and for almost 2 weeks i couldnt push myself too hard or I'd get the massive headache.

Had to take a good week of rest and then bring up the intensity slowly again, and keep it well managed

[gabriel_dubai]

Wow this was very eye opening for me, thank you.

[danielkanewske]

Very interesting. Thank you Dr Henselmans