Muscle Nerve Fatigue & Overtraining - Deal with Training Exhaustion

Overtraining or staleness is one of the bodybuilder's worst enemies. This condition usually occurs when complete recovery from frequent intense exercise stress is never really attained. Some symptoms of overtraining are, persistent muscle or joint aches and decreased muscle strength and/or size, elevated resting heart rate and blood pressure, heightened potential for injury, decreased appetite, fatigue, sleeplessness, impaired immune response. Does this sound like you? If so.. read on!

Intensive training over a very long period of time will almost always lead to a reduction in the body's ability to recover. If high-intensity training is continued, it becomes increasingly more difficult for the body to recover and, eventually, the above symptoms will begin to appear. When this happens, one clearly has entered the state of overtraining. After emergence of the symptoms related to overtraining, the only available recourse available is to alter and/or reduce training in order to allow time for the body's recovery processes to catch up. However, if such changes in training do not occur, the program will remain unproductive and might even become deleterious to body function and repair. Although overtraining in general refers to a whole-body response to stress, it is also possible to overtrain isolated body systems by chronically overtaxing specific physiological functions. Let me elaborate on this further.

In bodybuilding nervous-system exhaustion is one of the main contributing factors to the loss of strength and muscle size which occur because of staleness. Not only do motor neurons (nerves which innervate and control muscle fibers) stimulate specific muscle fibers to contract, but they also regulate the metabolism, growth and function of the muscle fibers. This ability of the nervous system to actually control muscle-fiber function has been termed "neurotrophism" in scientific journals fibers possible. It therefore becomes increasingly important for bodybuilders to develop a clear understanding of the events which stimulate neurotrophic processes and growth, and avoid those which can easily lead to nervous-system exhaustion.

Neuronophism is a term used to describe devoted to the study of muscle-nerve interactions. Fortunately for bodybuilders, lifting which stimulates neurotrophic events and muscle growth differs markedly from the type of training that rapidly leads to nervous- system exhaustion and overtraining of the neuro-muscular system. Most bodybuilders, however, emphasize the type of training that can easily exhaust the nervous system under the mistaken belief that such training will stimulate the greatest number of a phenomenon where never cells transport substances from the control center of the cell (nucleus) down through its elongated fiber to terminal points which connect to muscle fibers (neuro-muscularjunction). Once the substances reach the neuro-muscularjunction, they exert their influence on muscle structure, function and growth. It has been shown that a nerve which connects to a slow-twitch endurance muscle fiber is smaller in diameter than a nerve which connects to a more powerful fast-twitch muscle fiber. If these nerves are detached from their original muscle fibers and crossed over and connected to the other fiber, the muscle fibers will undergo dramatic transformations. The fast-twitch fiber will change to take on the characteristics of the less powerful endurance fiber whereas the slow- twitch endurance fiber wilt take on the characteristics of the more powerful fast- twitch fiber. Thus the original characteristics of these muscle fibers are completely reprogrammed by merely changing their nerve supply. The physiological changes produced just by switching nerve connections clearly demonstrates the importance of the nervous system in regulating muscle function, growth and responsiveness.

It becomes readily apparent from the above discussion that if traditional bodybuilding training programs can be redesigned to stimulate neurotrophic pathways and avoid straining nervous discharge reserves, more rapid gains in muscle size can be expected. This can best be achieved by carefully selecting a scheme of sets, repetitions and poundages which are intense enough to stimulate neurotrophic mechanisms but, at the same time, light enough so that nervous-system discharge reserves are not strained. If this does not occur, the over-training syndrome will emerge and then bodybuilding gains will either slow down, stop, or even regress! There is much more to bodybuilding than merely stimulating as many muscle fibers as possible. Bodybuilding should really be viewed as a means of stimulating neurotrophic pathways which control muscle-fiber growth and function. This can be accomplished without inducing nervous-system exhaustion. However, if one refuses to accept the fact that the nervous system controls muscle growth and can be exhausted from heavy training, it is unlikely that maximum gains will be realized from one's efforts in the gym. Nervous-system fatigue is to be avoided at all costs during training.

To induce muscle growth, conventional bodybuilding programs typically encourage lifting maximum poundages for a relatively low number of repetitions (6 to 8). And the proponents of such training argue that it is needed to stimulate the maximum number of muscle fibers possible. However, scientific experiments have clearly demonstrated that heavy training really does not stimulate significantly more muscle fibers than a program emphasizing moderate poundages (less than 70 percent of a single-repetition maximum). That is, lifting moderate poundages of about 50 percent of maximum will activate most available muscle fibers (fast, slow, and intermediate-twitch fibers). This was reported by S. Grillner and M. Udo (ActaPhysiolScand, Vol. 81, p.571,1971), who found that 9 out of 10 available muscle fibers are activated with a load that is 50 percent of maximum. On the other hand, when lifting weights that substantially exceed a load of 50 percent of maximum, the neuro-muscular system can only respond further by increasing either total nerve discharge rates to the muscle or synchronizing the discharge rates so that they appear closer together (reported by H.S. Mimer-Brown and colleagues in JPhysiol, Vol. 230, p.355, 1973) in order to produce a greater muscle-pulling force. Thus heavy lifting increases the rate and/or pattern at which nerve cells discharge. Neural discharges are what force the muscles to contract even harder to lift heavy loads. Consequently, heavy lifting dramatically taxes the discharge reserves of the nervous system which control muscular- force production.

Although over stimulating nerve-discharge rates might seem advantageous, it can very quickly tax recovery ability, and lead to development of the overtraining syndrome. Muscle strength can increase from such training, however, because the nervous system literally learns how to handle a greater amount of impulse traffic related to muscle- force production. The increase in impulse traffic comes about from either an increase in excitatory neuronal input to the muscle fibers, a decrease in inhibitory neuronal input, or a combination of both. The net effect is an increase in overall muscle excitation and strength development. Training which produces such effects severely strains recuperative abilities because of the high nerve-discharge rate and muscle-contractile activity. Thus recovery from heavy lifting normally takes prolonged periods of time.

Heavy training is not a highly successful means to train for size since the primary mechanism by which strength is improved is through an alteration in neuronal-discharge rates and not muscle growth. For example, powerlifters usually train with very heavy poundages, but their level of muscle development is often below what one would expect for the amount of weight that they can lift, and they often require prolonged periods of rest between heavy sessions. Stimulating neural-discharge rates is desirable if you are only interested in strength gains, but if you want to achieve accelerated muscle growth then a completely different plan of action is needed, one that will promote growth without inducing the overtraining syndrome.

Moderate-weight/high-volume lifting stimulates neurotrophic activity related to the enhancement of muscle growth and development. This is achieved without severely straining nervous-system reserves since the moderate poundages do not produce high discharge rates. Executing a high number of sets and repetitions with moderate poundages does, however, excite almost all of the available muscle fibers. More importantly, such lifting also stimulates neurotrophic pathways which induce muscle growth without exhausting nervous-system reserves.

The key to successful bodybuilding, therefore, is structuring routines to emphasize the stimulation of neurotrophic pathways which can alter muscle metabolism and thus influence its growth. Properly stimulating these nervous pathways, without draining their recovery ability, will produce growth without the frustrations of the over-training syndrome.