Cortisol is a type of steroid hormone mainly made in the adrenal cortex. It follows a daily cycle, peaking in the early morning and reaching its lowest around midnight and early morning. Its levels increase in response to low blood sugar, physical activity, and stress, which is why it's often called the "stress hormone".
It's important to distinguish normal cortisol changes due to stress from actual health problems. Too much or too little cortisol can be harmful. Having normal cortisol levels is important for our body's health.
Cortisol plays a significant role in maintaining general homeostasis. Here are some of the key functions it performs:
Glucose Metabolism: In early fasting conditions, cortisol stimulates gluconeogenesis and glycogenolysis, exerting a hyperglycemic action similar to glucagon, catecholamines, and GH. It also counteracts insulin. In late fasting, it may stimulate hepatic glycogen synthesis.
Immune System Suppression: Cortisol suppresses the immune system, which is useful in controlling inflammation.
Regulation of Fat and Protein Metabolism: Cortisol regulates fat and protein metabolism, often acting as a -lytic. Excessively high and prolonged levels can reduce muscle uptake of amino acids, facilitate proteolysis, and inhibit proteosynthesis in the same tissue, and promote adipose lipolysis.
Bone and Tissue Health: Cortisol seems to inhibit the ossification and synthesis of collagen, which may lead to skeletal rarefaction and tissue degeneration.
Regulation of Renal Filtration: Cortisol increases the renal filtration rate and excretion of phosphate and potassium, sodium, and water retention.
Digestive Health: Cortisol increases the production of hydrochloric acid in the stomach.
Memory Formation: In synergy with adrenaline, cortisol works to create memories of short-term emotional events.
Cortisol levels can increase due to several physiological or paraphysiological factors such as viral infections, caffeine intake, sleep deprivation, intense or prolonged aerobic exercise, serious trauma or stressful events, and alcohol abuse.
Excessive and prolonged stress can lead to high levels of circulating cortisol, creating an allostatic load. Chronic and severe excess cortisol is known as hypercortisolism, which can be primary or secondary.
Excess cortisol can lead to various health problems, including hyperglycemia and peripheral insulin resistance, increased amino acids in the bloodstream, increased muscle catabolism due to proteolysis, reduction of muscle proteosynthesis, reduction of collagen synthesis, reduction of osteosynthesis and predisposition to osteoporosis, increased wound healing time, and damage to the cells of the hippocampus.
Cortisol deficiency can be paraphysiological or pathological. Serious conditions of hypocortisolism include primary hypocortisolism or Addison's disease, Nelson's syndrome, secondary hypocortisolism or pituitary tumor, and Sheehan syndrome.
There are also factors that can reduce cortisol levels in the blood, such as post-resistance exercise, magnesium supplementation, omega-3 fatty acids, fish oil, music therapy, relaxing massages, laughter and humor, dance, Withania somnifera root extract (ashwagandha), and high-dose ascorbic acid (vitamin C).
During physical activity, cortisol levels temporarily increase and then return to normal as the individual returns to rest. This oscillation produces health benefits, strengthening the immune system, memory, appetite control, weight loss, energy levels, inflammation levels, sexual health, and more.
However, when physical activity is prolonged or performed too frequently without adequate recovery, it can lead to chronic stress, with consequent fatigue, compromised sleep, easy weight gain, mood drop, and reduced performance. Therefore, the objective of proper training management should be to avoid chronic excess or deficiency of cortisol, maintaining normal fluctuations in response to stressful situations and recovery.