and where does it start and finnish? What causes it to fatigue and recover? What chemical equation causes it to do so? What causes it to get better and worse.
Any ideas at all?
Does mental fatigue contribute to CNS fatigue? 
is the central nerous system just the brain and the spinal cord?
What about the nervous system within the muscle systems? do they suffer fatigue, do we suffer from the nervous system in the muscle and mistake it as CNS fatigue? How do we tell the two apart?
The central nervous system technically comprises the brain and spinal cord (which directly innervates the skeletal muscles).
I don’t think I have come across an adequate description of the mechanism of CNS fatigue. It’s one of those cases where we know it exists but don’t really know all the details of its mechanism of action (e.g. neurotransmitter depletion).
Furthermore, I don’t know if CNS fatigue is really a reduction in physiological capacity of the CNS or is instead an inhibitory mechanism imposed by the CNS to protect the musculoskeletal system from excessive strain.
Perhaps we all have been cofusing CNS fatigue with peripheral nervous system fatigue? after all, its the muscles doing the work, the muscles getting the punishment, why would it not the the nervous system within the muscles, peripheral nervous system, from causing the fatigue? If your muscles are exploding like crazy to create PB’s, surly the nerve attaching to the muscles are the ones coping the brunt of the exercise?? Toxins leached out of the muscles from intense exercise cause the nerve to be impaired, the nerve to become actually damaged from intense muscle contraction, makes more sence to me than to say the CNS is suffering!
Could it be CNS “fatigue” (expressed as delayed signal) --> CNS “auto-inhibition” --> musculoskeletal system protection?
Thoughts?
It’s the CNS that innervates the skeletal muscles, not the PNS.
To the best on my knowledge, the PNS only innervates smooth muscle and cardiac muscle.
That was my point. However, there might also be actual fatigue within the CNS. I just haven’t delved into the literature enough to know if there’s been any description of the mechanism. It might be a little of both.
Clemson has a pretty extensive knowledge base on this subject. He might know.
There are different definitions flying around out there. To me, C= central and it is based on the recovery curve for the CNS which differs in timing from muscular recovery and that difference (CNS takes longer) increases exponentially as intensity rises. Once recognized, the trick is to align the curves to allow optimal improvement and performance.
All things start from the brain -according to one theory- and as such it senses the danger, if you want and “shuts down”, or decreases in capacity. I don’t believe it’s “auto-fatigue”, more like a protective mechanism for the entire organism, a threshold and if this is surpassed, the system is in trouble.
Not an expert either! I am just theorizing here…
Glad to hear others on this!
Good post on how long it takes to recover.
Yesterday i looked up the nervous system, and the CNS is the bundle of nervous from the brain down along the spinal collume. It then branches out from the CNS into the muscle system and becomes the peripheral nervous system. I will try to do some more reasurch on the subject.
If we can understand what it is that is suffering fatigue, we should be better able to recover from its effect, one would hope!
It seems that it all depends on which definition of CNS you are talking about. There is the CNS fatigue that is the body’s self defense mechanism preventing complete peripheral muscle exhaustion. Then there is the type of CNS fatigue that comes from very high intensity work. The latter CNS fatigue usually feels ok while performing the effort. But takes a while for the body to recovery and fire properly. While the PNS (still using the latter definition) feels exhausting during the effort yet recovery is quicker than CNS fatigue.
One is a textbook definition of CNS, while the other is an exercise phenomenon that exists!
so, would spinal allignment issues therefore effect the CNS capacity to recover?
eg, you done a hard session, and during that you really worked your core ability. the next day your spine feels out of balance due to the muscles being tight from the workout. would that miss-alignment cause the CNS to be more slowly recovered? Perhaps a Chrio appointment when CNS recovery ability slows or perhaps a wkly event?
and ideas?
i very much doubt this. the idea that the CNS is mostly fatigued do to depeletion of certain substrates to me seems ludicrous. the output of the CNS decreases mainly do to inhibitory pathways which ineffeciently recruit the motor pool. through proper training inhibition can be bypassed ie. no more CNS fatigue atleast in the general sense. that means being able to perform at near 100% to 100% physical capabilities over and over day after day, now ofcourse there is an eventual detriement when stressors become maladaptive. to train the body to get around these inhibitory pathways we must elicit conditions during training which require continued prolifiration of benefical neural pathways. basically we must put the system under condtions which require continued and powerful motor unit recruitments. this involves among other things, taking advatage of the stretch reflex, the unique phenominon of the muscle tension associated with catching falling loads and in general training at maximums at all time if it be load, velocity or effort, ideally all at the same time because as power atheltes inversion of the force velocity curve is ideal.
I was talking to my Chrio today, and he says that he thinks perhaps it could be a nutrional thing. being where it is and all, perhaps there is a lag time for nutrients to arrive there? If it takes say as eg, 100ml of nutrients to arrive at say your legs, in the same time span, only 30ml of nutrients arrives at your CNS??? So the lag time also affects your CNS recovery time??
Perhaps?
though this can be contributory in an adaptive/maladaptive sense i doubt it is the major cause of CNS fatigue as we conceptualize it. if this were the case the CNS system in most athletes would recover and ruffly the same rate of the bodies structual units. we have evidence that the Cns can produce repeated bouts of high intensity stimulus as seen with the bulgarian weightlifter who would often spend day after use near maximal loads. another question we must ask ourselves is during jumping and sprinting our muscles have to generate muscle tensions equivalent to literally thousands of pounds, why can we jump and sprint (not necessarily at max effort) everyday generating muscle tensions dozens of times greater than our lifting maxs (bench, squat, deadlift) yet we cant lift those weights everyday, i think if we can answer that question we will have a true insight into exploiting the body to output at maximal ability whenever we want. as athletes i would think that would be ideal ie being able to use what you have gained whenever you choose not only every 10 days.
I like to think about the CNS in terms of light:
- Imagine yourself doing bicep curls. From the “perspective of light” we would probably see something in the way of the biceps shining brightly (through every repetition); the light slightly fading off towards to wrist and the shoulder; some very vague light emitting from the rest of the body (spine and neck probably slightly brighter than the rest).
- Now fatigue sets in and the reps become more difficult. The biceps are still blinking but wrists and shoulders are “turning on” a little brighter… the spine is doing the same.
- When you think you’re almost finished and struggle to do the last rep, some guy is pointing a gun at your head and asks for five more reps. Now suddenly, you light up like a Christmas tree. Even thou your biceps is perhaps slightly fading (in terms of light), the rest of the body seems to shine brighter (when you struggle for your life to do those five more reps you though you could not handle).
- During your last “extra life ‘n death” rep your’re emitting light through every conceivable part of your body, despite you doing just an isolated movement (bicep curls). Normally, you would have ended the set five reps earlier, and no Christmas tree would have been lit up in the first place.
Sprinting does pretty much the same; it kind of lights up your whole body for a while (more or less; depends also on level of performance). When fatigue sets in, light starts to fade away, first slowly but then at a faster rate: Your muscles fill with lactic acid and they don’t seem to respond as good anymore, but you still struggle to finish your run, so your CNS is burning exponentially in order to compensate. This goes on for a while, but somewhere a threshold is reached and it cannot cold such a charge any longer… and starts to dim fast.
Sprinting is not like isolated bicep curls, there is no extra pool of energy to draw from – you are lit up and that’s it. There’s no extra energy to draw from in that instant, you need to wait and recharge.
thats an intereting visulization, but i think u limit yourself, you have pretty much condemnded yourself to thinking that the CNS performs in a certain way based off of circumstantial evidence. we have all been through trianing which leaves us feeling depeleted or unable to perform at 100% but that does not necessarily mean that that is the way it has to be. for example just because you cant squat ur max every day now doesnt mean that there is no way that you can. i think your on th right path about thinking of the CNS in abstract sense because of its complexity it makes it difficult to point at on aspect which deteremines its effectiveness. so thinking in abstract can alow us to model the problem to find a solution. i really so no plausible reason why a person cant perform at maximum out put many many times, hell by not being able to do this we hinder ourselves as athletes especially in sports such as footbal which require repeated violent muscular contractions, wut good is it to be able to jump 40 inches into the air if you can only do it once and the rest of your jumps are at 35 inches. that number, 40 inches, adds nothing to your athleticism because its a feat a one tim apereshion which can only be called apon ever so often.
It’s just my visualization… but I think there is a limiting factor to our CNS; I see no reason why CNS-resources could be infinite. However, I think you are right in the sense that we don’t know ‘how much’ is possible. I guess the body is so complex and entangled with hierarchical and protective mechanism that what’s happening on the track might just be a part of the whole potential. Nevertheless, the issue with CNS-fatigue is very much real in the sense that whether it’s a protective reaction or a real depletion, the symptoms are real; we feel fatigued, we might have eye-flickering, sleep might be disturbed, coordination is off, potency lowered etc. How does one go about explaining such rather universal symptoms? I can’t se a reason why only inhibitory pathways during a specific exercise would cause these symptoms as a kind of residual effect. The CNS is not just wires that lead electricity, the CNS is living as well, and thus it’s subjugated to similar processes as other living cells too.
A beginner can’t stress the CNS as much as an elite sprinter can during a 100m run. That’s partially why a 14s runner can wait for 10min. and probably run the same time or even faster again. I bet Asafa or Gatlin would not be able to repeat 9.77s 10min. later. The higher the level of performance, the more it appears such performance is “tapped” into the potential CNS pool, thus more time required in between… although their bodies are tuned so well that they can make repeated 100m runs at 14s with a walk-back as much as they please.
O course, there are some extra ordinary circumstances where humans seem to exhibit almost unlimited power; a mother lifting a car when her baby is in jeopardy, or pushing the car with her legs so that her femurs break. But this is extremely rare cases, and an athlete will perhaps never be able to voluntary exhibit such bursts (without injury as a consequence). Although, training is leading us to such a direction, the question is only ‘how far’. And the further we go, the more time it seems it requires to recover.
A 40 inch jump adds to athleticism a new potential (even though the rest of the jumps level out at around 35). So if you previously had a p.r. at 35 inches (the rest being around 30), you now have a higher potential (40) as well as a higher basic level (35). It’s normal progression: 25…30….35………40…………….45……………………………50. When performance rises, it’s becoming increasingly more difficult to progress, thus, it requires more time in between. How fast and how far is also individually determined. Yet when you p.r. at 50, you can probably do a 40 or 45 whenever you please (that previously was a one time incident). But this will no go on indefinitely… there’s a threshold somewhere. When performance is driven further, there also seems to be a longer distance between ”basic level” and top-level”. So, let’s say a person doing a hypothetical huge 60 inch jump, then he cannot probably do a 55 inch jump whenever he pleases any longer.
no the CNS output is not limited but its ability to send stimulus to the muscles is far more vast than most people realize. i personllly have trained every day doing excercises that are balistic plyometric or CNS taxing,and doing them in high volumes. i am not special by any means anyone can train this way but it has to be organized in the proper way. also dont confuse overtraiing with CNS fatigue they can be the same thing but they are not always the same thing. like i said in my pervious post just because most people dont train this way and cant reproduce balistic achievements on a regular doesnt mean they cant. For the most part the vast majority of people train the same way. they lifet weights usually slowly unless they are olympic lifts, they run, and perhaps do plyometric training. that is it usually, and we are conditioned to believe this is the only way to train or atleast the best way to train. it is not the only way to train it can be effective but its isnt the only way to train. as for being able to a 50 inch vertical with subsequent jumps still being high, this is good this is the norm, but wouldnt you rather be able to just that 50 or near that 50 everytime? so would i.
so, if this is what You do every session,
could you give a sample layout of a weeks training you done, with times, weights, hights ect shown for comparesion, over a full wk.