It is generally accepted that if you need to lose weight, are stressed out or want to put on muscle mass, you need to hit the gym and hit it hard! While this approach will work for some people, most people’s eating habits and lifestyle choices will cause high intensity workout sessions to have a detrimental influence on their health. That’s because of the effect these sessions have on a person’s nervous system.

Without getting too embedded in the physiology, the nervous system has two main parts: the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS represents the largest part of the nervous system and includes the brain and spinal cord. The PNS consists of all the other nervous structures that do not lie in the CNS. The large majority of what are commonly called nerves are considered to be in the PNS.


Autonomic nervous system (ANS)

The autonomic nervous system (ANS) is that part of the PNS that acts as a control system, maintaining balance in the body. The ANS controls and regulates all life-sustaining functions you don’t have to think about; it’s your ANS that keeps you alive when you are asleep or when you get knocked unconscious. The ANS is divided into two parts: the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS). It is these two branches of the nervous system that we are interested in, so a brief description is in order.


Sympathetic nervous system (SNS)

The sympathetic nervous system (SNS) is often called the ‘fight or flight’ nervous system because the SNS prepares the body to fight or run from danger. When the SNS becomes the dominant branch of the nervous system, blood is shunted away from the internal organs and into the muscles and the periphery of the body (the arms, legs, etc.) to facilitate action. Since there is an increased utilization of nutrients and hormones, as well as greater tissue destruction when the SNS is engaged, it produces a catabolic (break down) effect on the body. The SNS is dominant when you are exercising, working or doing something that requires increased delivery of blood to the muscles; this includes stress.


Parasympathetic nervous system (PNS)

In contrast, the parasympathetic nervous system (PNS) is responsible for digestion and elimination and serves to regulate restoration, rebuilding and repair of the body, making it more anabolic (building/repairing). The PNS also stimulates immune function at night while you are sleeping.


It is important to realize that when the SNS is dominant, the functions of the PNS are proportionately shut down. Over time, over-stimulation of one system over the other can lead to clear-cut signs of imbalance:

SNS Dominance PNS Dominance
Poor digestion/⇓ salvation Strong or excessive digestion
Constipation Hyperactive bowel; colicky
Anxiety Incontinence
⇑Respiratory/heart rate Drop in blood pressure upon rising
Poor sleep quality; restless Poor sleep quality; hibernation
Night sweats ⇓ Perspiration
Orgasm/sexual inhibition Genital stimulation/increased libido
Waking un-rested ⇓ Respiratory rate
Nervousness e.g., restless/agitated Nervousness; depression; somnolence
Jittery ⇑ Mucus secretions
⇑Muscle tension Hands warm and dry
⇑ Inflammatory conditions ⇑ Gag reflex
⇑ Susceptibility to infection ⇑ WBC count

When you are thinking about what kinds of exercise would be beneficial, first begin by looking at each of the indicators above; the more symptoms a person has under one system, the greater the relative imbalance between the branches of the ANS. Although even one indicator, when chronic, can indicate an imbalance of significance, it is generally reliable to assume that the greater number of chronic indicators you find, the greater the problem and the more critical it becomes to modify diet, exercise and lifestyle factors to encourage balance.


Balancing the ANS with Exercise

A general rule of thumb is that if you can’t perform an exercise comfortably on a full stomach, the exercise is stimulating your SNS. With that in mind, you can easily envision how the great majority of exercises serve to further stress the SNS; keep in mind that SNS stimulation keeps the body in a catabolic (breakdown) state. If you are stuck in a SNS dominance in response to the stressors in your life, exercises that stimulate the SNS will only serve to perpetuate an already dysfunctional situation. Many people experience this as poor sleep, illness, anxiety, poor digestion and/or increased muscle tension.


If you are in a SNS dominant state, focus on chi balancing exercises to help rebalance your nervous system; these include gentle yoga, Tai Chi, Qi-gong or simply walking.


As your system rebalances, you will be able to tolerate more and more SNS stimulation through exercise. Start with one or two compound exercises (full body, pushing/pulling), keeping the training sessions under 30 minutes and supplementing with stretches that specifically restore muscle balance to improve overall nervous system balance. When you see sleep quality, energy levels, mood and response to exercise improving in concert with a reduction of chronic SNS dominance indicators (from the table above) you can carefully add more challenging exercises and increasing exercise duration and intensity.


We must let go of the ‘no pain, no gain’ philosophy. Instead think in terms of ‘train, don’t drain!’, and listen to your body tell you what it needs to function optimally. Nutrition also plays a key role in helping to rebalance your nervous system and keep you functioning optimally – feel free to contact us for more information.