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By Susan M. Kleiner, Ph.D.
Cortisol is produced in the adrenal glands, which reside at the top of the kidneys, and its release is stimulated by the hypothalamus. The daily release of cortisol follows a circadian pattern that is highest before waking and lowest at bedtime. Under normal conditions, the adrenal glands secrete between 20 and 40 milligrams of cortisol each day.
Cortisol plays numerous important roles, including control of substrate metabolism, immune response, wound healing, electrolyte and fluid balance, and more. Arguably, the least-known functions of cortisol are related to its impact on memory and its role in mood and feelings of satisfaction.
Cortisol moves freely into the brain, including directly into dopamine neurons. The dose of cortisol that produces beneficial effects on memory and elevated mood appears to be the daily amount secreted by the adrenal glands under normal conditions. Any stressor, especially a physical one, results in the release of cortisol. Physical and mental challenges evoke some level of discomfort, and ultimately result in the stimulation of cortisol release. Whether running a race or performing a symphony, cortisol is one component of getting out of the blocks or playing the first notes.
Cortisol is also released during high-intensity exercise to increase the production of glucose by the liver as well as free fatty acids into the bloodstream for energy production. In the brain, the release of cortisol combined with the euphoric nature of dopamine-releasing neurons may act synergistically to achieve a "runner's high," a state of "flow" and a sense of true satisfaction. According to Dr. Gregory Berns, a neuroscientist and psychiatrist: "Cortisol comes from stress, especially physical stress, and dopamine from novelty. Put the two together, and it is easy to see that novel physical challenges might be the best way to get the feeling of satisfaction we all crave" (Berns, 2005).
Dr. Berns goes on to describe why "a job well done" feels so good. The same combination of cortisol and dopamine, released and combined in the brain during physical exertion, helps us find a true sense of satisfaction from digging a ditch. Further research tells us that this is likely the same synergistic pathway that elicits a greater sense of reward and satisfaction from doing volunteer work for a cause, rather than just making a financial contribution (Ryff et al., 2004).
Just a little too much cortisol and your experience will shift from enhancement of mood, heightened concentration and improved memory to impaired concentration, overstimulation and anxiety. Cortisol is a catabolic steroid, so too much, too often will result in degenerative effects on the body. An excessive increase in cortisol levels that is maintained over time will switch from fueling the body for high-intensity exercise to a possible correlation with an increased risk of obesity.
Ideally, the body should exist in an optimal hormonal environment to support health. Switching into a stress response and releasing the hormones associated with stress was an adaptation to a dangerous environment—the well-known fight-or-flight response. In a life-or-death situation, we have the capacity to very rapidly fuel the body, think clearly, raise mental energy and flee. Quieting the stress response requires a period of recovery, with a lack of significant stress. Simple things like laughing or listening to music can reduce cortisol levels. Without recovery, the system has no "off" button. That's where things get ugly.
It's ironic that the very system that is designed to save us can lead to illness, poor quality of life and even a shortened lifespan. As mentioned above, intense exercise can transiently raise cortisol levels, allowing for a sense of enjoyment and satisfaction. After exercise and recovery, cortisol levels return to normal. Recovery is essential for cortisol to return to normal. The fast-paced, yet sedentary lifestyles of many people can lead to ongoing stress, where recovery never happens and cortisol levels stay chronically elevated. In this scenario, blood sugar levels are not elevated momentarily for fight or flight; rather, they are consistently elevated. Too much cortisol also induces insulin resistance, which over time overworks the pancreas until its function begins to struggle and increases the risk of type 2 diabetes (Aronson, 2009).
Furthermore, the constant release of intramuscular triglycerides into the bloodstream from elevated cortisol may lead to weight gain and obesity. Fatty acids are relocated to visceral fat, especially in the abdominal area. The proliferation of fat cells, combined with insulin resistance, alters appetite regulation: hunger rises and satiation diminishes.
From this initial onslaught ensues a long list of compromised health factors that only serve to increase the stress on the body, and further up-regulate cortisol production:
* Increased systemic inflammation
* Behavioral counseling
Ultimately, cortisol does not deserve its bad rap. Rather, a life out of balance is the culprit. The ideal strategy for enhancing the beneficial effects of cortisol and avoiding its deleterious impact is to maintain life balance. A balanced life combines a healthy diet, adequate recovery and good sleep patterns with physical activity and play, personal and community relationships, and creative and spiritual expression. This is how you and your clients can embrace the good of cortisol, while keeping the bad and the ugly at bay.
Berns, G. (2005). Satisfaction. The Science of Finding True Fulfillment. New York: Henry Holt and Company.
Brooks, K.A. and Carter, J.G. (2013). Overtraining, exercise, and adrenal insufficiency. Journal of Novel Physiotherapies, 3, 125, 11717.
Ryff, C.D. et al. (2004). Positive health: Connecting well-being with biology. Philosophical Transactions of the Royal Society, 359, 1383–1394.
Dr. Susan M. Kleiner is a renowned authority on eating for strength, endurance, power and speed, and the co-founder and co-CEO of Vynna®, LLC, an evidence-based, female-centric performance nutrition brand. She is an international columnist and speaker, and has consulted with professional teams, Olympians and elite athletes in all sports. Dr. Kleiner has been a faculty member at several esteemed universities, authored numerous academic chapters, articles and scientific manuscripts, and penned seven books, including the bestselling POWER EATING, 4th Edition (Human Kinetics, 2014).