The physiology of stress

While it may be the “most wonderful time of the year”, it can also be quite stressful. So many studies are emerging revolving around the negative impact of stress on the body in so many ways. What happens in the body when we are stressed? What is the physiology of stress?

Any physical or psychological stress can disrupt the equilibrium of our body’s systems and result in a stress response, which manifests either in our body or in our behavior. This stress response is moderated between the nervous, endocrine, and immune systems, in order to prepare the body to handle the challenges presented by the stressor. But if the stressor is intense (or just perceived as being so), repetitive, or prolonged, the stress response becomes maladaptive and harmful.

Stress generally affects all systems of the body, including the cardiovascular, endocrine, respiratory, gastrointestinal, nervous, muscular, and reproductive systems. With regards to the cardiovascular system, acute stressors, such as awaiting test results or slamming on the brakes to avoid an accident, cause an increase in heart rate, stronger heart muscle contractions, dilation of the heart, blood pressure elevation, and redirection of blood to larger muscles. This is also known as the “fight or flight” response. The endocrine system increases its production of stress hormones – epinephrine (adrenaline), norepinephrine, and cortisol – which act as messengers for these effects and provide the energy required to deal with the challenge. Once the acute episode passes, the body returns to its normal state. Acute stress manifests in the respiratory system as shortness of breath and rapid breathing due to the constriction of the airway between the nose and lungs. It has been shown to trigger asthma attacks and bring on panic attacks as well. The gastrointestinal system has hundreds of millions of neurons which are in constant communication with the brain, explaining that feeling of “butterflies” in the stomach. It can affect how quickly food moves through the bowels, digestion, and what nutrients the intestines absorb. Stress can also make the intestinal barrier weaker, causing changes in the gut bacteria, which can then impact the ability to think and affect emotions. With regards to the nervous system, stress will activate the sympathetic nervous system, which in turn activates the adrenal glands to produce more stress hormones. Stress affects the musculoskeletal system by tensing up the muscles to guard against pain and injury. Finally, in the reproductive system, acute stress can cause impotence and adversely affect menstruation cycles.

As the duration of stress lengthens, it becomes chronic. Stress responses go through three different stages in this progression:

  • Recovery Phase – following the acute phase, the body begins to repair itself by lowering cortisol levels and normalizing the physiologic responses but remains on high alert. 
  • Resistance Stage – if the stressors persist, the body will adapt by continuing to secrete stress hormones, which keeps the body’s physical response to stress elevated – symptoms include poor concentration, irritability, and frustration.
  • Exhaustion Stage – the body’s immune system begins to weaken as a result of the suppressive effects of stress hormones, causing symptoms of burnout, fatigue, depression, anxiety, and reduced stress tolerance.

Chronic stress manifests in all of the systems of the body as well. It can increase the risk of hypertension, coronary artery disease, heart attack, and stroke. It results in a long-term drain on the body due to the continuous activation of the nervous system and has been linked to the development of chronic fatigue, metabolic disorders like diabetes and obesity, depression, and immune disorders. Chronic stress can affect testosterone production resulting in a decreased sex drive and can negatively affect a woman’s ability to conceive and her postpartum adjustment. Finally, it causes the body to be in a relatively constant state of guardedness, which may trigger other musculoskeletal reactions in the body. For example, lower back and upper extremity pain have both been linked to stress, especially job-related. Both tension headaches and migraines are associated with chronic muscle tension in the shoulders, neck, and head. Muscle tension and eventual muscle atrophy all promote chronic, stress-related musculoskeletal conditions. 

So what can we do about it? Exercise and mindfulness have been shown to be effective remedies for stress, both acute and chronic. So head on over to LYT Daily for hundreds of on-demand classes or to the LYT Studio for LIVE Zoom classes with feedback from our fabulous LYT instructors. See you on the mat!



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