Humans have two adrenal glands, one atop each kidney. Each gland's small size --- 3 by 1/2 inches -- belies its essential role in making hormones critical to basic physiological functions such as exercise. Diseases that stop or reduce the production of these hormones are called adrenal insufficiency disorders. If you have one of these disorders, seek your doctor's advice about your exercise routines.
Normal Adrenal Function
The medulla -- the inner portion of each adrenal gland -- secretes the stress hormones epinephrine and norepinephrine. The cortex -- the outer portion -- is responsible for dozens of steroid hormones, most notably cortisol and aldosterone. Cortisol, also called hydrocortisone, affects the body's balance of glucose and combats inflammation. Aldosterone regulates the body's balance of water, sodium and potassium, and thus influences blood volume and blood pressure, according to Colorado State University.
Primary Insufficiency
In wealthier countries, primary adrenal insufficiency, or Addison's disease, most frequently results from autoimmune destruction of the adrenal cortex. In poorer countries, it is most commonly caused by tuberculosis infections. Symptoms of Addison's disease include escalating muscular weakness and fatigue, gastrointestinal disturbances, salt cravings, low blood sugar and weight loss. If undiagnosed and untreated, Addison's can lead to extremely low blood pressure, dehydration, shock and death. People with Addison's typically take hydrocortisone pills as well as fludrocortisone, a replacement for aldosterone, notes the National Endocrine and Metabolic Diseases Information Service.
Secondary Insufficiency
Secondary adrenal insufficiency disorders result from tumors, infections or other problems that hinder the brain's pituitary gland from producing ACTH, or adrenocorticotropin hormone. Without ACTH, the adrenal cortex stops making cortisol. The symptoms and treatment of secondary insufficiency are like those of Addison's disease, except that fludrocortisone is often unnecessary. The Merck Manuals Online Medical Library notes that because aldosterone synthesis often continues, there are usually fewer problems with low blood pressure and constricted blood volume.
Cortisol
Exercise generally stimulates the healthy adrenal cortex to make more cortisol. People with adrenal insufficiency disorders cannot respond to exercise in this way, and must often ease gradually into new regimens. Many can and do engage even in physically demanding sports like long-distance running. But they may need to take higher doses of medication when they do. Gentler forms of exercise generally do not require higher medication doses.
Aldosterone
Exercise stimulates the healthy adrenal cortex to release more aldosterone, which causes the kidney to excrete more potassium and conserve more sodium. This enables the body to conserve water and maintain an appropriate blood pressure. Because people with Addison's disease cannot step up their aldosterone production in this way, they must drink large amounts of fluids during and after exercise. Sports drinks with high potassium levels are not recommended.
References
- Addison's Disease: Owner's Manual: Chapter 6--Exercise
- Colorado State University: Pathophysiology of the Endocrine System: Adrenal Glands
- "The Endocrine System in Sports and Exercise"; W.J. Kraemer and A.D. Rogol (eds.); 2005
- Merck Manuals Online Medical Library: Secondary Adrenal Insufficiency
- National Endocrine and Metabolic Diseases Information Service: Adrenal Insufficiency and Addison's Disease
- EndocrineWeb: Your Adrenal Glands
