Sympathetic Muscle Tension and Stress

One of the well-known phenomena that accompany the stress response is the spontaneous and uncontrollable action of the sympathetic nervous system on the musculoskeletal structures of the body. Stress, muscular tension and pain often go hand in hand.

The Alarm or Stress Response of the Sympathetic Nervous System

bungee-jumpingWhen the sympathetic nervous system is suddenly stimulated by a stressor, there is an almost immediate increase in the body’s ability to carry out unusually vigorous muscle activity, even in individuals who would ordinarily not be capable of it.This almost prodigious increase in strength is facilitated by a cascade of physiological changes that is precipitated by stressful situations.

These changes, which take place in a matter of mere seconds, include:

  1. Increased arterial blood pressure.
  2. Increased blood flow to the muscles along with a corresponding decrease in blood supply to the gastrointestinal tract and the kidneys, which are not needed in mounting the body’s rapid response to the threat.
  3. Increased rates of cellular metabolism, which speed up the body’s rate of functioning.
  4. Increased blood glucose concentration, which provides increased levels of energy.
  5. Increased glycolysis in the liver and in the muscle, also a factor in energy supply.
  6. Increased muscle tension and preparedness to work, which increase tone and strength.
  7. Increased mental activity, which provides acuity, alertness and greater focus on the threat.
  8. Increased rate of blood coagulation, which protects the body from significant blood loss if it should sustain minor cuts and puncture.

The combined effects of the mobilization of virtually all principal organs is what enables the body to perform significantly more strenuous physical activity than it is ordinarily possible. Stress of any kind, physical, emotional or mental, excites the sympathetic system, whose purpose is to provide above-normal activation of the body’s resources. Because of this stimulation, the stress response is often referred to as the sympathetic stress response.

Emotional vs. Physical Stress

The sympathetic system is activated during physical danger, but it is also and more frequently activated by many real or perceived emotional stressors. Guyton-Hall cite the example of anger or rage,

…which is elicited to a great extent by stimulating the hypothalamus, signals are transmitted downward through the reticular formation of the brain stem and into the spinal cord to cause massive sympathetic discharge; most aforementioned sympathetic events ensue immediately. This is called the sympathetic alarm reaction. It is also called the fight or flight reaction because an animal in this state decides almost instantly whether to stand and fight or to run. In either event, the sympathetic alarm reaction makes the animal’s subsequent activities vigorous.
–Textbook of medical physiology by Arthur C. Guyton & John E. Hall, 11th ed.

Chronic Stress

The same exact response can be elicited even daily in individuals exposed to multiple or repeating stressors, such as a negative environment, a dysfunctional relationship, poor working conditions, or difficult socio-economic challenges. In this case, the muscle tension and sympathetic stimulation can be so great and so frequent that the body cannot return to a normal state of relaxation, in which case a chronic stress condition can ensue.