Overtraining and Adrenal Insufficiency

Running, or any aerobic training in moderation, has a positive effect on health. There is a point of diminishing returns, where chronic stress from overtraining, which is common in runners, may be linked to problems in the adrenal gland. Overtraining syndrome (OS) has been linked with adrenal insufficiency. There is a direct link between stress and the adrenal glands, and the physical stress of overtraining may cause the hormones produced in these glands to become depleted. 

Adrenal Insufficiency: Symptoms and Causes 

Adrenal insufficiency refers to the inability of the adrenal glands to produce a normal quantity of hormones, which leads to a reduced ability in the individual to cope with stress. Adrenal depletion is a milder form of insufficiency, while Addison's disease is a total adrenal gland shutdown, which involves more extreme symptoms which require longer to correct. Addison’s disease is an autoimmune disorder, which has life-threatening complications.

Symptoms of adrenal insufficiency can be directly traced to a reduced secretion of certain hormones when under stress. Within the medulla, or inner core, of the kidney, both epinephrine and norepinephrine are release during the fight-flight response to stress. Stress in the body can be physical, mental, emotional, or even imagined stress, and all have the same impact on the release of hormones and the effect of stress on our body. 

Within the adrenal cortex, or outer shell, aldosterone, cortisol, and cortisone are regulated. These hormones are more critical in body function. Aldosterone helps kidneys retain sodium and excrete potassium. If production falls too low, the kidneys are not able to regulate salt and water balance, causing blood volume and blood pressure to drop, which can result in a life-threatening situation. Cortisol has many functions such as maintaining blood pressure and cardiovascular function, slowing the immune system's inflammatory response, and balancing the effects of insulin in breaking down glucose for energy. Cortisol is also involved in regulation of the metabolism of proteins, carbohydrates, and fats, as it stimulates the liver to raise the blood sugar as needed, in response to metabolic demands, physical activity, and stress. Cortisol has a long half-life in the blood and if often thought to be the body's long-term response to stress, in contrast to adrenaline which is a very immediate and short-term response. Cortisol production is regulated by adrenocorticotrophic hormone (ACTH), made in the pituitary gland.

The hypothalamic-pituitary-adrenal (HPA) axis is highly involved in our body’s short-term and long-term response to stress. Other hormones related to the stress response include corticotropin-releasing hormone and  adrenocorticotrophic hormone. In cases of adrenal depletion, these other hormones are often found to be in short supply (in early stages of adrenal stress) or they can be found to be abnormally high, while another hormone is in short supply. The HPA axis functions to maintain hormone levels by balancing hormones ateach level of the axis. The hypothalalmus releases corticotropin-releasing hormone (CRH), which causes the pituitary to release adrenocorticotrophic hormone (ACTH). ACTH causes the outer cortex of the adrenal gland to increase in size and to release cortisol. At times, serum cortisol may be found to be at a normal level, while ACTH is low. Adrenal depletion involves the entire HPA-axis, and the earlier the problem is discovered, the less the axis will be affected.

Low serum cortisol is a marker of adrenal depletion. There are several symptoms of low cortisol levels, although they are vague and often related to other disorders. Some symptoms include:

• fatigue
• unrefreshing sleep 
• ill-defined malaise
• loss of ambition
• increased fear and apprehension,
• scattered thinking
• decreased concentration and memory
• short fuse
• hypoglycemia symptoms
• sugar cravings
• slow recovery from illness
• allergies or autoimmune disease
• increased achiness or arthritis
• nausea/ no appetite in a.m.
• excessive consumption of caffeine or other stimulants
• tendency to feel best towards evening
• decreased sex drive

Low cortisol levels have been linked to the following:

• personality/lifestyle/occupational factors lead to adrenal insufficiency:
• perfectionism
• a history of severe physical or emotional trauma or prolonged stress
• shiftwork
• teaching or healthcare profession/middle management position
• overtraining 
• any job where the individual feels trapped or powerless
• high consumption of refined flour and sugar
• hypothyroidism

Adrenal insufficiency can be divided into two types, a primary and a secondary form, depending on the length of disease and the primary hormones affected. Primary adrenal insufficiency results from a loss of both cortisol and aldosterone secretion due to the near or total destruction (Addison’s) of both adrenal glands. Most reported cases of primary adrenal insufficiency result from destruction of the adrenal cortex by the body's own immune system and the process takes months to years. Often times, individuals are not aware they have the disease and may me misdiagnosed with another similar disorder. Secondary adrenal insufficiency can be traced to a lack of ACTH, which causes a drop in the adrenal glands' production of cortisol but not aldosterone. This is most commonly found with overtraining in athletes. Symptoms are not usually apparent until over 90% of the adrenal cortex has been destroyed and very little adrenal capacity is left. This is due to the non-specific nature of symptoms and their slow progression. Symptoms are more times than not, often missed or ignored until physically stressful event or crisis, known as an Addisonian crisis, which is characterized by a sudden, penetrating pain in the lower back, abdomen, or legs, along with severe vomiting and diarrhea, followed by dehydration, low blood pressure and a loss of consciousness. 

Symptoms of adrenal insufficiency include:

• chronic, steadily worsening fatigue 
• severe fatigue/low stamina 
• irritability and depression
• weakness/muscle spasm
• loss of appetite/weight
• increased pigmentation of the skin
• inability to cope with stress
• allergies
• faintness and low blood pressure
• nausea/vomiting
• poor circulation
• salt loss/salt cravings 
• painful muscles and joints
• inability to digest food
• hypoglycemia
• intolerance to heat or cold
• lowered resistance to infection

In the recovery from mild cases of adrenal insufficiency, if caught early, correction can occur in a matter of months. In more severe cases, complete correction may require several years; replacement therapy is not suggested in these cases if normal cortisol levels exist, as the body will cease to produce essential hormones naturally. Addison’s disease require lifetime replacement therapy of corticosteroids. The prognosis for those with Addison’s disease is that with replacement medication every day, the individual can lead a normal crisis-free life. There are no specific physical or occupational restrictions, though an individual must learn their limitations and find coping methods for stress. 

Kelly Brooks, Ph.D.

Further Reading:

http://217.160.4.72/NutritionPractitioner/Issues/Issue_11_1/Articles/3%20Overtrainingformatted4_IC_ML3.pdf

http://europepmc.org/abstract/MED/9662686/reload=0;jsessionid=KiPHmJeAq4FTl1cMYqqy.22

http://europepmc.org/abstract/MED/15717662

http://link.springer.com/chapter/10.1007%2F978-0-585-34048-7_2?LI=true