What is Cortisol?

What is cortisol? Cortisol, known as the regulator of immune response, is a hormone controlled by the adrenal cortex. This powerful hormone is also known as an adrenalcorticol hormone, a glucocorticoid and hydrocortisone or simply cortisone. Cortisol has a catabolic (muscle breakdown) effect on tissue and is associated with a decrease in anabolic (muscle growth) hormones like IGF-1 and GH. Thus reducing levels of cortisol is ideal for an athlete to achieve tissue growth and positive adaptations to exercise training.

Playing many different roles in your body, cortisol can have a negative impact on sleep, mood, sex drive, bone health, ligament health, cardiovascular health and athletic performance, potentially causing fatigue and inflammation. Its primary functions are to increase protein breakdown, inhibit glucose uptake and increase lipolysis (the breakdown of fats).

What does an increased cortisol level mean to me? While cortisol in normal amounts is necessary for proper metabolic function, a chronic elevated cortisol level has adverse effects on your health, mood, body composition and performance. Here’s the cycle: elevated cortisol secretion from physical or mental stress causes fat, protein and carbohydrates to be rapidly mobilized in order for you to take action against the stressor. This is sometimes referred to as the ‘fight or flight’ response. The mobilization of these nutrients in addition to epinephrine and a number of other endocrine hormones allows you to take quick action when presented with stress. During this mobilization, cortisol and adrenaline increase while DHEA (Dehydroepiandrosterone) and testosterone decrease. A chronic elevated cortisol level causes your body to enter a state of constant muscle breakdown and suppressed immune function, increasing your risk of illness and injury while reducing muscle.

How do I know if my cortisol levels are high? Mood swings, lack of motivation to train, loss of muscle and loss of appetite are all symptoms of an elevated cortisol level. Sound familiar? That’s right, overtraining syndrome. If you are not taking steps to modulate your cortisol, you are breaking down your muscle, storing fat and getting sick, all of which don’t make for a fast racing season. A more scientific approach is to have your testosterone/cortisol or IGF-1/cortisol levels tested. A suppressed ratio of either IGF or testosterone over cortisol is a sure sign of decreased exercise capacity and overtraining. There is also strong evidence that athletes exercising in a carbohydrate-depleted state experience greater increases in cortisol. Decreased frequency of menstrual periods in women (amenorrhea) has been linked to insufficient energy availability that triggers a stress hormone response and suppresses estrogen and progesterone (Loucks et al., 2004).

What affects cortisol secretion? Stress, which includes trauma, infection, disease and exercise, is the primary factor that dramatically raises cortisol levels. Wait a minute, exercise is a stressor? High intensity exercise and prolonged exercise both increase cortisol levels, which remain elevated for about 2 hours following the exercise bout. Repeated exercise without appropriate rest results in chronic elevated cortisol. Additionally, poor diet, inadequate supplementation and lack of rest also play key roles in cortisol secretion.

How does cortisol affect my endurance performance? It is only with chronic elevated cortisol levels that your performance will suffer, but the effect is dramatic. Excess cortisol suppresses your immune system, producing a greater risk of upper respiratory infections. On top of that, your body will be in a catabolic state — breaking down muscle and storing fat. In addition to reducing your muscle and getting sick, suppressed testosterone means suppressed recovery. Aerobic and anaerobic muscle fibers need time to repair and recover from hard workouts to improve their capacity to exercise. Elevated cortisol and suppressed testosterone do not allow you to maximize your recovery, leading to slower performance gains. A Swiss study of elite male cyclists suggested that ratios of anabolic to catabolic hormones (ie. testosterone/cortisol or IGF-1/cortisol) may be useful markers for the detection of overtraining (Hug et al. 2003). In fact, scientists use this Free Testosterone/Cortisol ratio to evaluate an athlete’s training state. Daley et al. (2004) showed a strong relationship between elevated cortisol and decreased testosterone that was most dramatic 30 minutes after endurance exercise to exhaustion. A ratio where cortisol is elevated indicates overtraining, so the modulation of this ratio can be key for those athletes who are susceptible to overtraining. Additionally, amenorrhea in women and low testosterone in men may increase risk for stress fractures.

Notes From The
Endurance Research Board

Evidence that cortisol response to exercise can be modulated:
Although true resting levels of cortisol do not differ between trained athletes and sedentary controls, exercise and recovery periods are associated with elevated cortisol release. Even 15 minutes of sub maximal cycling exercise has been shown to elevate post-exercise cortisol levels in the saliva (O’Conner et al. 1996). A study of marathoners (Cook et al., 1987) found salivary cortisol levels to be elevated during the race, but were maximal at 30 minutes after race completion. Cortisol release in response to exercise appears to be altered depending on the time of day that exercise takes place (Kanaley et al., 2001). Cortisol levels were much higher during and after exercise at 7am than at 7pm or midnight. Double sessions for one hour and fifteen minute bouts at 75% of VO2 max were found to elicit higher cortisol response if only separated by 3 hrs of rest versus 6 hrs rest between bouts (Ronsen et al., 2002). Carbohydrates consumed during exercise have been shown to decrease the immune and cortisol response within 30 minutes after 6 x 15min maximal running bouts when compared to a non-caloric, sweetened placebo (Bishop et al., 2002). There is strong evidence that athletes exercising in a carbohydrate-depleted state experience larger increases in circulating stress hormones (cortisol) and a greater suppression of immune function (Braun, 2004). An important take home message for athletes and coaches: the regulation of blood and body glucose levels is within the athlete’s control and this can seriously impact their health and ability to enhance their exercise performance and training adaptations.

By Sally Warner, Ph.D.

How can I modulate Cortisol? Cortisol can be modulated through rest, nutrition and supplementation. First, since repeated bouts of exercise cause chronic elevated cortisol, it is key to get plenty of rest between workouts. Double workouts in one day are detrimental if there is not sufficient rest between the workouts (see side bar by Sally Warner Ph.D.). Next, as mentioned earlier, depleted carbohydrates leads to higher levels of cortisol, so keep up your carb intake. Don’t bonk! Finally, there are a number of supplements that are also helpful in modulating cortisol. A blend of high levels of B vitamins, branched chain amino acids, glutamine and key adaptogens like ginseng, rhodiola and ashwaganda all help you adapt to ‘stress’ by helping regulate the body’s endocrine hormones also known as the ‘fight or flight’ response to stress.

Recommendation: Since the scope of this newsletter is nutrition, we will detail our nutrition and supplement recommendations and briefly list lifestyle changes which help modulate stress. The most important step is to reduce any unnecessary stress in your life. Although sometimes the most difficult thing to do, it is also the most effective, so make sure to manage the stress that you cannot eliminate. Time management, relaxation methods, yoga, and hobbies are some effective techniques. Complementary to managing stress, it is crucial to stick to a sensible diet. Poor nutrition — including high fat or high protein diets — can adversely affect cortisol control. In times of high stress many of us crave these types of meals which we know are detrimental to our health. It is also important to maintain carbohydrate intake that supports training hard and good health while doing so. A recent study by Green et al. (2003) supported carbohydrate intake during endurance exercise to reduce blood cortisol levels for up to 1 hour after exercise. A literature review of hormonal responses to exercise by Steinacker et al. (2003) suggested that with glycogen deficiency, cortisol levels are elevated and induce a “myopathy-like state” in skeletal muscle. And it’s not only what you eat but when. Make absolutely certain you have breakfast, which will help regulate your blood sugar and your cortisol prior to workouts. A recent study showed that a carbohydrate drink consumed during exercise (500ml per hour of a 6.4%) can reduce symptoms of overreaching during a period of high intensity, high volume training (Halson et al., 2004). To ensure that you do not deplete your glycogen stores, be sure to take in carbohydrates while exercising along with a high quality recovery drink with high levels of carbohydrates immediately following exhaustive exercise. The bottom line: do not attempt endurance training on a high protein, low carbohydrate diet — it’s a kiss of death (see sidebar by Sally Warner).

A high dose of B vitamins and calcium can help regulate the endocrine hormones necessary for proper cortisol control. Supplementing with 4+ grams of branched chain amino acids (BCAAs) and 6+ grams glutamine following exhaustive exercise can have a dramatic effect on cortisol. In fact, in a 25-week study of intercollegiate swimmers the group supplementing with BCAAs and glutamine showed a significant decrease in serum cortisol.

For added cortisol control, consider some herbal applications. Adaptogens are some of the more popular supplements that help with cortisol control, which include ashwaganda, rhodiola and ginseng. By definition, adaptogens help the body adapt to high levels of physical and mental stress. The result is a controlled ‘fight or flight’ response that helps modulate cortisol levels. Another class of herbs common in Traditional Chinese Medicine (TCM: magnolia bark, theanine (from green tea), epimedium and tyrosine) have shown promise in regulating cortisol. A recently released book titled The Cortisol Connection by Ironman triathlete, cyclist and Ph.D. Shawn Talbott, goes into detail on these and other TCM herbs.


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About the author

Robert Kunz - First Endurance