This blog is part one of a two part series on stress and the role it plays on pain at a physical level. Part two will go into different ways to manage your stress to better manage your pain.
The concept of stress should not need any introduction. It's a normal part of everyday life, right? What if I told you that stress could be causing you pain? What I told you that finding ways to manage and decrease your stress could help you decrease your pain, reduce your risk of injury and even improve your immunity?
The Physiology of Stress
Stress isn't just a state of mind. Behind that feeling of anxiety and worry is a chain of reactions within the body which have a pretty detrimental outcome for our health. The medical jargon can get pretty complicated so I'll do my best to keep it simple. To get started, here is a list of systems in the body that are involved in the stress response, what they are and what they do:
Autonomic Nervous System (ANS) = the part of the nervous system responsible for control of the bodily functions not consciously directed, such as breathing, the heartbeat, and digestive processes.
Sympathetic Nervous System (SNS) = a division of the ANS whose primary process is to stimulate the body's fight or flight response. This component of the ANS utilizes and activates the release of noradrenalin, which can lead to dilation of the blood vessels, increased heart rate and pupil dilation.
Pituitary Gland = the major endocrine gland, a pea-sized body attached to the base of the brain that is important in controlling growth and development and the functioning of the other endocrine glands.
Hypothalamus = a region of the forebrain below the thalamus which coordinates both the autonomic nervous system and the activity of the pituitary, controlling body temperature, thirst, hunger, and other homeostatic systems, and involved in sleep and emotional activity.
Corticotropin-releasing hormone (CRH) = a hormone that is released by the hypothalamus in response to stress. It can suppress appetite, increase subjective feelings of anxiety, and perform other functions like boosting attention. It can also increase an inflammatory response in the body.
Adrenocorticotropic hormone (ACTH) = produced in the anterior pituitary gland, its principal effects are increased production and release of cortisol by the adrenal gland.
Cortisol = produced within the adrenal gland and released as a response stress and low blood-glucose concentration. It functions to increase blood sugar, to suppress the immune system, and to aid in the metabolism of fat, protein, and carbohydrates. It also decreases bone formation.
And to link all of that into a flowchart:
Stress > hypothalamus to release CRH > anterior pituitary gland to release ACTH > binds to adrenal glands > release of cortisol > SNS primed
But what does this all mean?
For starters, having the SNS primed to have the body in a fight or flight mode has a wide range of effects. This system is designed to make our body super efficient in a time of danger. It arms us with the extra strength to fight off the present danger or the speed to escape it. This involves increasing blood flow to major muscle groups (deemed important), heart rate, availability of metabolic energy stores and muscle tension while decreasing/slowing digestion, spinal reflexes, immune system and sexual function. Meanwhile, having a suppressed immune system can decrease your resistance to viruses and other illnesses while the body's ability to repair itself becomes diminished.
And when stress becomes chronic ...
These reactions sound pretty extreme and that's because they were designed for extreme situations. They are part of our evolution as humans. However, what was deemed a reasonable stressor to activate the SNS has changed over the years. In today's life, we are constantly bombarded with work, financial or family issues, relationship problems and bad news stories to the point where we can't even let ourselves relax and unwind. With this constant activation of the SNS, the body is functioning at a level it cannot physically or psychologically maintain. The long-term effects of constant cortisol exposure are also associated with chronic stress include impaired cognition, decreased thyroid function, and accumulation of abdominal fat.
Thanks for reading Part 1 of Stress & Pain. Part 2 will include some information from some studies about stress in different settings as well as a few different ways you can help manage your own stress levels.
Sources include -
The Physiology of Stress: Cortisol and the Hypothalamic-Pituitary-Adrenal Axis by Michael Randall (2011). Available at http://dujs.dartmouth.edu/2011/02/the-physiology-of-stress-cortisol-and-the-hypothalamic-pituitary-adrenal-axis/#.WUOSn2iGPIV
Beyond Mechanical Pain: Stress & Pain by Alison Sim. Available at http://beyond-mechanical-pain.usefedora.com/