WHAT IS CNS FATIGUE really?

Expert Discussion Advanced Sports Sciences
61

yep I have some references (copied in below). I have to say that my idea i more or less an hypothesis. It is based on current thinking in neuro science. I have difficulty finding a good English reference, my ideas stem from two former professors who published only their general model stuff in Dutch, but have a look at this presentation:
www.medicaljournals.se/jrm/strokerehab/pdf/mulder.pdf )

Evolution was about fight or flight: moving the body. Our sensory system served this evolutionary purpose: retain body(read brain) integrity. Hunger, thurst, fatigue, DOMS should in my opinion be seen as factors that force action (to move or not to move). However, the body might have someting extra, for emergency purposes (for example we have an anaerobic system, possibly because if an anticipatory sprint is not sufficient and the predator is still chasing you). The body does not want to use it very regularly, because the need for recovery makes vulnerable (an encounter with a predator when you are sleeping under a tree…)

We have anecdotical evidence from persons who did remarkable things when being in emergency. The same in sports. The question is whether we can use the bodies hidden potential tour advantage.

you can download a pdf containing information on the emotional motor system via the following link

http://keur.eldoc.ub.rug.nl/wetenschappers/1/480/

62

the part about inhibtion is what i am trying to get to. the CNS does not have a pool of resources from which performance is dependent, and the idea that inhibition blocks of a portion of said resources like a towns emergency water tower is a fallacy. the CNS is far more complex than that. neurological inhibtion is the key and this is what must be overcome to increase work load and combat “neurological fatigue”.

63

[quote=“lorien”]

i agree with most of what you stated. but i think you are combining CNS adaptation and adaptation of the organism as a whole, or atleast singular traits. also i am NOT trying to tell you that a athlete should sprint everyday by any means becasue as you stated it will not improve performance. i was only using the examples of sprinting and lifting as indicators of the underlying neural mechanisms, and to show that the CNS does not work on a substrate debt type of system.

64

Or perhaps its just a chemacal reaction that takes time to recover from. and if you are fatigued, and a sence of fright or flight comes over you, that causes a chemical reaction that causes the CNS to respond aggressivally. Then the next day, i bet you’ll suffer as more chemical reactions need replacing than normal.
Perhaps?

65

Is there really need to distinguish and separate the two supposed forms of adaptation you are talking about here? With which purposes?

In my experience the two concepts may define realities very very close to each other. Is there any better indicator of whole organism adaptation than CNS adaptation anyway?

66

it is imperative to distinguish between adaptation of the organism and adaptation or rather reorganization of the CNS. the CNS is the control mechanism of the subordinate traits. these traits can all supercompensate to a degree on their own but all ultimatly are interelated making them suseptable to interference from each other. but this allows for multiple concurent supercompensations. ordinarily this will occur with everyones training but all at once ie all traits are trained simultaniously but if the stressor is specific traits can be distinguished, and trained from oneanother. forgive the diatrid but it is important to distinguish between adaptions because thats the essence of selective training and being able to elicit desired training results.

67

From a functional perspective you cannot seperate the nervous system adaptation from the organism adaptation.

It is the same I think. For example: sore muscles can only be percepted by the brain. The brain can create the response(healing behaviour, like getting a massage or stay resting).

The system is complex however.
Studies on DOMS for example have shown that the amount of microdamage does not correlate well with the intensity of discomfort that is felt. THis is in concordance with neuro theories like the gate theory of pain by Melzack and Wall and also the more recent neuro insights.

http://www.garfield.library.upenn.edu/classics1982/A1982NR10500001.pdf

The function of DOMS might be straightforward: it is a signal to the system that performance is limited. Studies have shown that training continuation despite DOMS does not increase injury risk. However performance is limited

The brain is the integrator concerning performance ability. Peripheral input from muscles and organs can and will be used. A change in the brain (for example motivation, [occupational] stress] can lead to changes in the periphery (for example tensed muscles). The system also goes the other way round.

Dualism (brain vs periphery) is very outdated in neuroscience. However, there are still fans of Descartes.

68

differentiation is extremly important on a a functional level because it is the control mechanism not the strucutal although many traits occur only in the CNS others do occur in the other tissues of the body and the PNS, especially the PNS when it comes to the training of the feedforward system. i can combat your argument about DOMS by stating that i myself do not expereince it after intense training even when it consits heavily of eccentric contractions. i attribute this mostly to diet and life style.

69

I dont get much of a DOMS either. But getting DOMS and suffering from CNS stress are too different things. I suffered from CNS stress over the last two days, yet only very mild DOMS, nothing that training would suffer from had the CNS stress not been there. The only reason i did suffer a bit of DOMS was due to lack of CORE work in the previous mnth. But that is changing from last wk.

70

I am happy to hear your points ,sijmker,as your words seem to fit and give further context to the picture of the puzzle I put together piece by piece primarily through the daily use of the OmegaWave Technology in training and therapy during the last few years.
I am hence compelled to a functional perspective,as you correctly point out,but could not agree more with your words.

71

Nothing to be forgiven here,at all! Only good food for thought and discussion…

I may agree with you on your concept of “selective training” but I am also convinced that for “selective” training may be,adaptations in the organism will rather always be “general”,as righteously expected in such a complex system…

72

Pakewi, do you have any ideas whether CNS fatigue is different for short (sprints) and longer durations of exercise (marathon)?

After long running there are also indications of “central fatigue”

http://jap.physiology.org/cgi/content/abstract/94/1/193

also; from muscle physiology we have some indications that low-frequency fatigue is much longer present than high-frequency fatigue.

Should this mean that it’s possible that we can perform high intensity exercise quite often, but that it is [only] possible if we keep low frequency fatigue (volume) in control (minimization)

regards
Stefan

73

the body responds to the stressors imposed on it the more specific the stressor the more specific the subsequent adaptation. but there is a general effect on the organism as a whole as these stressors are interelated. trait 1 effect trait 2 do some degree. for example i have seen work down with an athlete on his start the goal of the trianing was to effect the start an no other aspects of the race, the traits that were most need to improve the start were trained and upon completion of the training period ( a few weeks) the only thing that was efected was the start all other aspects of his sprint were the same as proven by video analysis. duering training there is an overall overtrainined/fatigued state which must be monitered regardless the traits trained. most people train in this way to some degree. you max bench one day and another you use lighter loads for power training, or even uper body plyometrics each training a different aspect of strength but each interelated. this is a gross example and traits can be further distinguished from each other.

74

very interesting question, how are you defining high/low frequency fatigue, simply by the intensity and duration of muscle contractions? i personally believe any submaximal training (anything under 97% of your maximum) has a negative effect on training as a whole or atleast with the way i train. maybe this is the reason i never get sore, i think submaximal effort produces low grade inflamtion in muscle as does incorect motor patterns.

75

What is it you train for? Event wise! Charlie has trained many different people (not just ben) and many of them from nothing. All of these people did lots of sub max effort training. Lots of med balls, lots of tempo, lots of bb’ing weights. If you read some forums on TEMPO and particually on what Charlie has to say, you will notice that sub max work is NOT only just for recovery! There ARE other reasons! These OTHER reasons are part of the reason why those athletes run so consistantly fast.
When i implimented this training into my training group 5yrs ago, the sub max work after only a few mnths work showed up massively by consistant performances over the 100 + 200 and in the heats semis finals carnivals.
Do a SEARCH on tempo. or better still, buy his CFTS book. in there you will find WHY sub max work is included, not just recovery!
Unless your only Weights training for weights training goals, but then you need to specifiy that i would think??

76

maximal can also apply to effort or velocity/acceleration. so you can use weights in the gym that are a certain percentage of your max and move the weight by attempting to use as much force as possible ie high speed (realtivly speaking). personally i am a sprinter and a football player.

77

I am curious to know whether my hypothesis can stand this test?

Are you able to perform after such workouts? Or do you think you cannot perform (self-fulfilling prophecy)

In my humble opinion you get DOMS when you do too much different than what your system is used to handle (“sum” of sport + non-sport load)

My point was that DOMS and [CNS] fatigue (whether it exists or not) are signals belonging to the same system (the brain) that wants to keep its integrity.

Looking forward to your response

regards
stefan

78

I think there is only one control system. I agree that some adaptations occur central and others occur peripheral. However the system is very plastic I think. Do you agree?

79

In addition to the previous post,

If something changes peripherally than centrally things will also change I think. The other way round goes as well.

Performance however might still much more complex than the underlying motor abilities (or traits). The whole might be more than the sum of the parts.

What was mentioned about fatigue state is interesting [based on current thinking about two factor performance models [fatigue-fitness]. Should we aim for starting the next training session with minimal fatigue (surpercompensate between sessions) or do we for example supercompensate over microc/mesocylce?

Or can we do both, but not aiming for both things at the same time. Do we need variation in fatigue state for optimal adaptation?

80

regarding high/low frequency fatigue

high frequency fatigue: diminisched force output at high frequency of electrical stimulation. At low frequency no drop

low frequency fatigue: dimished force output at low frequency of electrical stimulation. This takes a long recovery time they state (days). It is present after prolonged eccentrics.

article: Jones DA. High and low frequency fatigue revisited. Acta Physiol Scand 1996;156:265-270.

However the author states that low frequency fatigue may be present, it will not result in functional impairments, since the body can adapt…

More interesting articles
Blonc et al. Int J Sports Med 1998; 19: 272-276.

different recovery duration for 5 x 6-8 max speed bicycle exercise against increasing braking force (force-velocity test)

subjects: twelve male physical education students

peak power output was 10-14% lower during 4th and 5th set if recovery duration between each sprint was 30s in stead of 24hours.

Raastad T Hallen J. Recovery of skeletal muscle contractility after high- and moderate-intensity strength exercise. Eur J Appl Phys. 2000; 82:206-214.

high intensity protocol:
warm up: increasing loads for five sets of squats, four sets of front squats and one set of knee extension.

2x 3 x 3 squats and front squats @ 3-RM + 3 x 6 Knee extension @6RM P6’ / 4’. Total duration of session: 90 minutes

medium intensity protocol: same as above only intensity 70% of 3/6RM

Subjects: 8 male powerlifters, a javelin thrower and a speed skater, familiar with this type of training.

Squat 3-RM; average 169 kg
front-squat 3-RM: 121 kg
average squat jump height: 37cm (mediocre)

results: performance measures included squat jump, maximal force by electrical stimulation etc.

"all performance measures showed the same pattern of recovery after the 100% protocol. there was a drop in performance of 12-22% post-exercise, Recovery was biphasic, with rapid recovery occuring during the first 11 hours, followed by a levelling off or a second drop in performance until the next morning, 22h after exercise, All variables returned to baseline levels after 33h after exercise.

In the 70% group, recovery of performance measuren was at baseline againg after 3 hours.

==> What does the above then mean? I think it does’nt tell much.

If you want to supercompensate before you begin your next session, it might be wise to follow Charlie’s rule of 48 hours??

What would happen if you reduce volume of high intensity exercise? Can you perform it everyday during a period of the year to boost performance??