One of the primary objectives of 180DegreeHealth is to provide information, not on the dangers of sitting around on the couch pounding big bags of Doritos and 3 Liter bottles of Mountain Dew, but on the dangers of the modern exercise and dieting fads that have arisen in response to the unhealthy modern diet and lifestyle. 

A few weeks ago I wrote a post that included some thoughts about the dangers of bodybuilding.  In the comments, Eric Lepine, who has an encyclopedic knowledge of exercise physiology, bodybuilding, and other forms of intense physical training, mentioned that his research has led him to the conclusion that some of the dangers of intense training stem from Central Nervous System (CNS) Fatigue.  I invited him to write an article for the site about CNS Fatigue – sharing some of his thoughts. 

In short, when you train hard it’s not just the muscles that need to repair and recover.  Hard training taxes the CNS, and this can take far longer to recover from.  Not that you should be afraid to exercise, but awareness about the involvement of the CNS in physical exercise can help you customize your own exercise practices to find just the right dose of intensity, workout frequency, and volume – if vigorous exercise and fitness is something you are interested in pursuing.  As Eric points out in his article below, what YOUR central nervous system is capable of withstanding and how long it takes to recover is completely individual. 

Thus, like everything that I advocate in terms of metabolism, understanding how your body works, and focusing inward on determining the diet and lifestyle that is appropriate for YOU, the same can be said of the CNS.  You have to assess your recovery and adjust it in a way that allows you to find your sweet spot – making progress without encountering the ravages of overtraining that surface most commonly as sleep loss, a loss in strength, a drop in metabolism/body temperature, fatigue, declining libido, and other health problems both minor and major.  Below are the thoughts that Eric wanted to share. 

As a reminder, you can sign up to catch my talk for the Small Changes Big Results Health Summit tomorrow HERE

Also, just a few days left to purchase the 35 audio recordings, mine included, before the price doubles at the Healthy Living Summit HERE

Central Nervous System FATIGUE: Can it be measured and, should we care?

By Eric Lepine

Hans Selye long ago insisted that the objective should never be to avoid stress entirely, stress being an inevitable element of life and a natural by-product of our daily activities. And, especially insofar as the world of training and exercise is concerned, once we recognize that to reach our full potential, we must first determine our optimal level of stress, we can then set out to call upon our adaptive energy at a rate and in a direction adjusted to the innate structure of our physiology and psychology. This, of course, is no easy task, and one that requires much practice and a level of almost constant self-analysis.  

Working with a physiological diagnostic software called Omegawave Sport, a tool originally developed by the Russians for use in their space program to measure central nervous system (CNS) functions (and one highly regarded by the likes of Mel Siff) we can, in fact, very specifically measure CNS function and thus, fatigue and overload which, in that respect, become very real with very measurable physiological effects.  

According to Charlie Francis, one of the greatest sprint coaches to ever live, “all CNS work should be very high quality work in terms of effort and technique.” More broadly speaking, Francis defined CNS fatigue as a “comprehensive concept, which links a number of bodily systems and functions together, for example endocrine, muscular, neuroendocrine, neuromuscular, etc.” Given this premise, it follows that the kind of stimulus required, based on the goals we have set and the current state of the individual, will be the prime determinants of the the type of training we should submit ourselves (or our athletes/clients) to.

On paper, this certainly sounds like the right idea.

In other words, we are talking about those factors that take time, beyond that which can be explained purely by muscular recovery, to generate an equivalent or higher performance than was seen in the training session or, if you will, the time it takes for the CNS to recover to the point of readiness for additional high intensity work and which differs significantly in time frame from muscular recovery. 

Inevitably, when CNS fatigue or overload is observed—depending on what we want to call it—we also notice marked changes in various performance measures such as increased ground contact in any plyometric activity, decreased power output, slower reaction times, etc.; these all constitute very clear, real and measureable signs of CNS fatigue.

Of course, the type of athlete, the goals of said athlete, the type of training and given training phase, etc. will all serve to dictate how important it is to actually account for these observations and what, if any, will be the impact on the overall training and trainee. Athletes and trainees dealing with movements requiring high levels of proficiency and skill would generally do best to avoid training of said skills in a state of fatigue, which could otherwise compromise both performance and safety. Where this is less of a preoccupation, there will be a bit more leeway although where general health is concerned, extra care and precaution are always warranted.

What appears quite clear is that the length of recovery time needed to bring the CNS back to normal function depends greatly on the degree to which it was depleted, the recovery ability of the individual, as well as the various recovery methods used (interestingly, “recovery methods” can also cause “habituation” as well as “over-stimulation” hence, care must be used here as well). The rate at which the CNS recovers is a very individual characteristic, with some trainees having tremendous capacity, and others having very limited capacity. Activities requiring high rates of force development (RFD) and maximum voluntary contraction (MVC) usually will place the greatest demands on the CNS, thus depleting it more rapidly.

Aside from general CNS overload, fatigue can also be of sympathetic or parasympathetic nature, each with its own set of symptoms as well as preferred recovery methods. 

I mentioned briefly at the beginning of the article one method used for tracking CNS parameters. If one wishes, there are also more simple methods of tracking one’s level of training “readiness,” which are not unlike Matt’s past simple recommendation of using a refractometer (Eat for Heat) for gathering more empirical knowledge relative to overall hydration levels and metabolic state. One of the simpler methods is the finger tap test, a very basic albeit less accurate method. Basically, you tap your index finger as quickly as possible within a given timeframe (usually 10 seconds) and keep track of your numbers. A drop in performance could mean a drop in CNS output capacity. 

A more accurate approach favored, among others, by national judo and wrestling national teams, is the handgrip dynamometer (a squeezing device commonly used in the rehab setting, which is held in the hand and allows the measuring of grip strength). Again, keeping track of numbers over time (usually in the morning but, also at three different times daily), any significant drop or constant decrease over time could indicate that the trainee is not fully recovered or not recovering as quickly as anticipated.

Another simple method, used by track cyclists and speedskaters, is the vertical jump, again with the same idea: a drop in performance is usually a sign to back off. In all of these examples, an inferior result doesn’t always suggest that you should completely avoid training that day but, at the very least, volume (and in rarer cases, both volume and intensity) should be modified. 

Other useful sympathetic and parasympathetic nervous system markers one could keep track of are basal temperature, resting heart rate, blood pressure and Achilles tendon reflex. Any noticeable sleeplessness, lack of concentration, and even trembling post-workout could also be indications of CNS fatigue. 

One element we have yet to broach here pertains to the development of resistance to fatigue under any given situation, the latter implying that an appropriate level of stimulation be imparted on the CNS in order for this adaptation to occur. Matt Perryman not long ago wrote there could be many reasons for us to believe that training to cause « adaptation of the systems that cause adaptation » could be a worthwhile endeavor. But, problems arise in that, in spite of the numerous opinions on the topic, we aren’t really sure of how to gauge or interpret CNS fatigue. Being that fatigue, level of motivation and readiness always are, at least in part, of a subjective nature, we are often left with more questions than answers.

However, by virtue of what we call fuzzy logic–a concept perfectly adaptable to the world of exercise physiology—or by the very notion that none of this is in any way, shape or form a linear process, we can simply remind ourselves that much here is really just a matter of degree and, given this, CNS fatigue need not concern the everyday trainee to too great an extent. At least not with the tediousness typically required for elite athletes, and as long as some level of caution and awareness is implied. 

In that respect, once we understand that several types of equilibrium exist (stable, unstable, metastable and multistable), we can more readily consider the possibility that there may be more than one type and more than one degree of fatigue occurring during and after a given causal/training session. This presupposes that we should always consider the possibility of sudden and unexpected changes, whether these manifest through inexplicable sudden loss of form or exceptional improvement in performance.

Ilya Prigogine showed that this perpetual state of non-equilibrium or dynamic homeostasis may in fact be a source of impending order. Being that all systems comprise subsystems in a continual state of fluctuation, in which one or more fluctuations can totally disrupt the existing organization and produce unpredictable leaps to ‘chaos’ or to a higher level of organization, increasing levels of order can occur spontaneously or by chance through a process of self-organization and, this applies to any and all physiological process, including fatigue and CNS fatigue and its ensuing consequences.

The above points, in effect, are what constitute the “art” portion of the art/science of training conundrum…