Muscles and How They Affect Your Nervous System

Muscle Tension

While contraction and relaxation are the principal actions of muscle, there is in fact a second “activity” which is called muscle tension. This is part of the muscle contraction process. The tensing of muscle is a fascinating phenomenon. It is controlled by the CNS-the brain. Because the muscle tone is controlled by the CNS, it can occur without our conscious awareness. Here are a few examples:

Muscles tense:

• in preparation to move parts of your body, whether or not the movement occurs
• when you become threatened mentally or physically
• when you imagine doing some movement with your body to protect an injured area
• when used inappropriately, such as sitting.

Under normal conditions, muscles have a resting level of activity. If you add weight to a muscle, like bending your neck to read this page, then the level of muscle activity increases. This occurs at the CNS level and the muscle level. The result is that more muscle fibers contract and the muscle strength increases. Over time if the muscle stays contracted, it becomes tense/weakened – a learned response.

As more is demanded of the muscle, the CNS and the muscle tries to contract even more in an attempt to generate more strength. But as muscles contract and get shorter, they also get weaker. As they get weaker, they fatigue even more quickly. So the more contracted and tense a muscle becomes, the weaker it is, and the quicker it will fatigue. To put it simply: they become ‘pooped out’ from being over worked.