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View Full Version : What is CNS fatigue? CNS Recovery?


Pat McElhone
03-15-2010, 11:24 AM
Does anyone know what is CNS fatigue actually is? I do not mean the symptoms of CNS fatigue (loss of speed, coordination, strength, etc). I mean the pathophysiology behind these terms?

Steven Low
03-15-2010, 05:59 PM
Well, you already know my position.

I'd probably say it's a combination of neuroendocrine and neurotransmitter disruption and/or depletion from sympathetic overstimulation... depends on the individual person what breaks first.

If you wanna go digging in pubmed good luck. Last time I tried it I didn't get much, but that was a while ago so maybe there's better stuff out now.

Garrett Smith
03-15-2010, 06:15 PM
There's a million dollar question.

Donald Lee
03-15-2010, 06:49 PM
I debated whether to post this in this thread or in the TRAC thread, as it's slightly unrelated, but here is something Mike Tuscherer recently wrote:

To answer your original post... I don't think either way will yield vastly different results for you as long as you manage your stresses properly.

In Bob's case we were noticing a pattern. He would train for a period of weeks and after about 3 weeks, he noticed feeling beat up and if he continued to push, an injury sometimes resulted. So we're doing 3 on 1 off to account for his natural tendency.

Once TRAC comes online, this will be a much easier question to answer as well. When your physiological indications get to a certain point, you know it's time to back off and let things go. This will allow you to both manage reduced training loads for workouts or schedule entire deload weeks based on physiological response.

Regarding the deload before a contest, I don't even really do them anymore. My current thinking is this -- I am not trying to lift beyond what I've done in training. If I go to the meet and I lift how I did in training, then I will have a good day. And on that same note, if I got stronger throughout the training cycle and displayed that strength without the deload, then why add a deload for the contest?
You know, this is a pretty tough question and one that I haven't totally figured out. There are obviously many ways to do it.

Another interesting thing I've learned from TRAC is that what reduces CNS potential the most is not lifting maximal weights. It's avoiding maximal weights for a prolonged period. Exactly what that period is, I can't tell you. I know for me, it's about a week. I need to lift something in the 80%+ range at least once per week or my CNS potential will drop. This is showing to be true in others as well.

With that in mind, how do you approach deloading? It just highlights something we all know to be true -- you have to time things right. Lift heavy in close enough proximity to the contest that you are well prepared, but not so close that you are overtrained. Tough call.

Pat McElhone
03-16-2010, 08:19 AM
Well, you already know my position.




I was at my local market on Saturday and at the checkout was Netter's cartoon of the autonomic nervous system and 2 Chiros talking about sympathetic/parasympathic imbalance. They asked me if I wanted a free neurology consultation. I politely said no thank you. Nonetheless, there it was...the ideal of yin and yang, balance, imbalance, etc.

I do not think there is anything concrete out there. In fact, after looking around the internet for a few days, I am beginning to think CNS fatigue is just a catch all people are using instead of saying "tired" to sound smarter. Neuro-endocrine, symapthetic, parasympathic, autonomic are all common used terms when discussing CNS fatigue, but they are not even part of the central nervous system.

Steven Low
03-16-2010, 12:46 PM
I assume when people mean CNS they are referring to any of the neurological factors that are associated with strength and the detriment that occurs when tired/overworked/etc.

I'm not sure why you're so adamant about dismissing sympathetic/parasympathetic imbalance though.

In any case, I dug this up and it may give you some leads on what you're looking for:

http://jap.physiology.org/cgi/content/full/85/6/2352

Garrett Smith
03-16-2010, 02:20 PM
That abstract is pretty cool.
This hormonal profile is distinctly different from what has been previously reported for other types of overtraining, indicating that high-relative-intensity resistance exercise overtraining may not be successfully monitered via circulating testosterone and cortisol. Unlike overtraining conditions with endurance athletes, altered resting concentrations of pituitary, adrenal, or gonadal hormones were not evident, and exercise-induced concentrations were only modestly affected.
Ha! Real research pointing in the direction of why strength training plus short-to-no metcons can be such a great way to rehabilitate ex-metcon-addicts and their damaged HPTA axis.

For those who haven't figured it out yet, most "CF-style" metcon is a lot closer to endurance training than it ever was to strength training.

Can't remember where I just saw it (FB?), but Robb Wolf has now coined a term, the "CrossFit Flu". That is a keeper.

Pat McElhone
03-16-2010, 02:34 PM
I assume when people mean CNS they are referring to any of the neurological factors that are associated with strength and the detriment that occurs when tired/overworked/etc.

I'm not sure why you're so adamant about dismissing sympathetic/parasympathetic imbalance though.

In any case, I dug this up and it may give you some leads on what you're looking for:

http://jap.physiology.org/cgi/content/full/85/6/2352

Steven,

Thanks for the article. I will enjoy reading it tonight.

It is not that I am so adamant, it is just I am at the point of trying to understand it all and a lot of terms do not come together. I read "CNS fatigue" all over the place now days. I try to learn about it, but I can find nothing about it. The term everywhere tends to be "CNS fatigue", but it seems refer to general nervous system fatigue. As you know, CNS fatigue is limited to the central nervous system, it does not include the autonomic nervous system, the motor neurons, the neuromuscular junctions. All of the later seem to be what needs to recover at least as much as the central nervous system. In fact, I would say the periperphal nervous system is taxed significantly more then the CNS with high intensity training.

It is the same with sympathetic vs para, it can answer a lot of things, but not everything. Is resting the sympathetic, the same as increasing the para...no, not to me, but maybe to others it is.

Thanks again for the article.

Donald Lee
03-16-2010, 09:58 PM
If you happen to be willing to read a whole book on the topic, Kreider and others wrote a book called "Overtraining in Sport:"

http://www.amazon.com/Overtraining-Sport-Richard-Kreider/dp/0880115637/ref=sr_1_1?ie=UTF8&s=books&qid=1268801843&sr=8-1