Stress & The Nervous System
The nervous system is one of the most incredible, yet inconspicuous, aspects of the human anatomy. It functions like a fine-tuned call center by accepting, analyzing, and disseminating information, making sure that accurate messages are sent to the correct recipients at exactly the right time. It is divided into two primary divisions: the central nervous system (CNS) and the peripheral nervous system (PNS).
The CNS consists of the brain and spinal cord. The PNS includes all the other nerves (that aren’t a part of the CNS). The PNS can be broken down into two divisions--the sensory and the motor. The sensory division manages all tactile, auditory, olfactory, gustatory, and visual information. The motor division makes sure that the central nervous system’s messages (nerve impulses) reach their intended recipient (the muscles). The motor division can be further separated into the somatic nervous system (SNS) and the autonomic nervous system (ANS).
The ANS is of vital importance because it constantly and consistently manages the body’s ability to maintain internal homeostasis. It coordinates all the body’s unconscious activities including digestion, respiration, circulation, and elimination. In fact, the ANS influences every aspect of our physical and mental well-being. Even though we’re not aware of its essential actions, the ANS and its three branches--the sympathetic, parasympathetic, and enteric--are always hard at work.
The sympathetic division of the autonomic nervous system activates the body’s flight or fight response; the parasympathetic division, its rest and digest response. The actions of the enteric nervous system are confined to the gastrointestinal tract. Recent research has confirmed that the enteric nervous system, working in conjunction with the vagus nerve acts as the body’s second brain. If you have ever had a ‘gut feeling’ about something, that’s the enteric nervous system at work.
Key Point: The body is always listening and adapting to the messages it receives from the autonomic nervous system. And it’s this adaptability that largely determines an athlete’s aptitude for training, competition, and recovery.
The human nervous system is hardwired to react to stressors, and to become quiet in the absence of them. The symptoms of overtraining, poor performance, recurring injuries, frequent illness, and emotional burnout occur when an athlete’s autonomic nervous system becomes over-stimulated and can no longer respond or adapt to the demands being placed upon it. ANS overload can also be expressed as an inability to shut down when it’s appropriate.
While the ANS plays a key role in managing the unconscious functions of the human body, the somatic nervous system is in charge of controlling and directing all muscular activity and movement. Just as the autonomic nervous system can become overloaded and malfunction, the somatic nervous system can become chronically over stimulated and incapable of switching off. When this happens, our muscles get tight; our bodies become rigid, and we become less flexible and physically adaptable.
Key Point: The body can only adapt to and benefit from the amount of stress it can process on a neurological level.
The specific amount of stress that serves an adaptive purpose can vary greatly from one athlete to another. While most competitive athletes know that it’s necessary to regularly reach or exceed their training stress threshold in order to elicit positive gains, there’s another side of the equation to consider: training benefits can be diminished by as much as 40% if the body isn’t allowed to recover completely after a hard effort. More training is not always better, especially when it becomes a non-adaptive form of chronic stress.
ACUTE & CHRONIC STRESS
Stress is an unavoidable aspect of modern life. And most of us are under a great deal of it, sometimes more than we realize. Our work and family lives are often stressful. Illnesses and injuries are always stressful. Even the activities we use to relieve stress (like training for and competing in a sport) can be stressful.
There are two main types of stress--acute and chronic. Acute stress is the immediate reaction to a threatening situation. Once the threat has passed, the function of our nervous system returns to normal with no damaging, long-term effects. In fact, there is some evidence to support the idea that small and regular amounts of acute stress can increase the brain’s capacity for processing information more quickly.
Chronic stress is continuous. And it can have a lasting, negative impact on both our physical and mental health. The body responds to acute stress by producing the short-lived hormones adrenaline and norepinephrine. It makes cortisol (in the adrenal glands) to facilitate our adaptation to long-term, chronic stress. Unfortunately, the body is not well-equipped to handle the sheer volume of chronic stress--or increased amounts of cortisol--that are now considered a ‘normal’ aspect of everyday life.
A chronically elevated cortisol level is extremely catabolic (destructive). It weakens the immune system, breaks down bone, muscle, and connective tissue, and interferes with thyroid hormone production. It promotes fat storage and speeds up the process of aging. Because a high cortisol level compromises both the quantity and quality of sleep, it will significantly reduce the body’s ability to recover from an illness or injury.
What steps can we take to mitigate the harmful effects of stress we all experience—to some degree or another—to protect and preserve our overall health and performance? Stay tuned for an answer to that question in my next post!
About the author
Jackie Cruickshank Cohen is an NBHWC Board Certified Health and WellnessCoach, True Cellular Detox Certified Practitioner, author, and elite master’s athlete.
