From The Nervous System to The Muscle: The Order of Stimulation

In order to develop muscle it is important to know the order of stimulation.  Whenever you start an exercise program there are many physiological processes that are at work. It is important to understand that the body builds from inside out.  What I mean is that the first system that is directly affected by exercise is the nervous system.  The nervous system is a network of intricate nerves that send impulses (synapses) to the cells of the body. The nervous system is also in constant communication with hormones. The endrocrine system is responsible for the release of many different hormones that all help regulate the body’s internal physiology.

When a person begins an exercise program their hormone levels and nervous system have a low tolerance to stress. This level needs to be developed and increased to help support any further progress in the health of the systems. Over time the synchronicity of the nervous system and endrocrine system begin to improve allowing the person to increase their overall intensity and duration of a stress response (exercise).

Initially the body perceives the new exercise regime as a stress to the body and a disruption in homeostasis. The cells are under attack and this causes, in some cases, ill effects. With a low tolerance to physiological stress the body produces cortisol, which is a stress hormone that inhibits anabolism.  In order to avoid an increased release of cortisol it is important to work within your threshold point. The intensity level must be increased overtime in a gradual format to avoid over production of stress hormones.

Over a period of weeks the body will adapt to gradual increase in intensity and will begin to be less threatened by the stimulation that is being subjected.  Once you have overcome the initially nervous system adaptation cycle, the muscles are then able to be used to respond to the continuing overload of intensity.

As the frequency of exercise becomes more prevalent and the intensity has been gradually increased, the systems of the body are then able to establish new growth patterns.  The cardiovascular system and the muscular system are two systems that are directly related to increased stimulation.  The muscles communicate directly with the nervous system by motor units that are attached to the muscle cells.  When the muscle contracts there are messages sent to the brain to illicit the proper response. The more intense the contraction the more output from the nervous system and muscle becomes.  In order to build muscle tissue it is important to progressively overload the muscle fibers. However, keep in mind that you also must stay within your own biochemical threshold level. You must train with the correct amount of intensity to stimulate the muscle without increasing the production of cortisol. The cardiovascular system will also increase in its ability to take in and deliver oxygen to the working muscle tissue.  The more trained the muscle is the higher the hormonal threshold will become. This is why people who have been training on a regular basis for so long can workout with high intensity and aren’t too fatigued from the exercise session. While those that are not as conditioned will become overtrained trying to perform the same feat as the conditioned person. This is a mistake that many upstarts make.

Often times folks who are de-conditioned will join in a fitness class and will try to keep up with those that have been taking the class for awhile.  Those that have been taking the class for a couple of weeks or longer have developed their threshold of progression to match the intensity with their own physiology.  The upstart who is too over-zealous will go beyond their threshold and will become overtrained within a short period of time. They will feel sick and sore the next day. This sick feeling will produce a negative feeling about ever going back to exercise.

It is important to work out within your own stress threshold.

Once your nervous system, endrocrine system, muscular system and cardiovascular system threshold has been improved over a period of months. The next level of increased stimulation will directly effect the muscle fibers.  This is when the muscles go into a hypertrophy and hyperplasia state. This is when you can really have fun with making significant changes with your physique.  It takes time to establish the neuromuscular system.  It is important to never take any addition lay offs from training, because this will only set you back.

Here is a brief review of the order of stimulation

1. Nervous system adaptation

2. Endrocrine system adaptation

3. Cardiovascular system adaptation

4. Muscular system adaptation

5. Hypertrophy and Hyperplasia

Daryl Conant, M.Ed

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