There are two hormones that get thrown under the bus all the time: insulin and cortisol. Neither of these is bad; we need them to be healthy and successful athletes. Their bad rap comes from being misunderstood. So in this blog post, we’ll set the record straight on cortisol. 

What is cortisol?

Cortisol is your natural alarm system. It’s your body’s primary stress hormone, works with your brain, and affects many parts of your body. It’s made in the adrenal glands, which are little triangle-shaped organs that sit on top of your kidneys. Think of it like Goldilocks, you don’t want too much or too little, you want it to be just right. 

What does cortisol do?

Despite getting a bad rap or often being made out to be the villain, cortisol plays many important roles in the body, especially for athletes. For example, it:

• Keeps inflammation down
• Regulates blood pressure
• It affects heart rate & breathing 
• Increases blood glucose
• Controls sleep & wake cycles

High cortisol in athletes 

Cortisol’s a savvy hormone; it changes very quickly, unlike many other hormones, which take days or weeks to see a difference. Cortisol increases in response to stress, which can be physical or psychological. While there are an infinite number of psychological stresses, the most common causes of physical stress in athletes are:

• Calorie deficit (not eating enough to support training in addition to physiological processes)
• Going long periods of time (>5 hours)  without eating 
• Insufficient sleep (aim for 8-10 hours per night)
• Not taking enough days off (aim for at least one recovery day per week)
• Excessive training loads (volume, intensity, or both)

Elevated cortisol levels

It can derail important functions, not to mention make training miserable. Signs you might have elevated cortisol levels include:

• You often get cold sores 
• Headaches
• Issues concentrating
• Digestive problems such as bloating, gas, constipation, or loose stools
• Trouble sleeping 
• Missing or irregular periods

Low cortisol levels in athletes

“Adrenal fatigue” was all the rage for several years. Supposedly this phenomenon occurred when someone was overstressed for too long, and the adrenal glands wore out, resulting in low cortisol levels. We now know this isn’t how it works. The adrenal glands aren’t fatigued; they’re doing exactly what they’re supposed to do. They follow directions from the pituitary gland in the brain. When you’re chronically stressed, certain brain parts sense the high-stress levels and reduce cortisol production.

Think of it this way: if you keep inviting a friend to go out and they say no every time, eventually you stop inviting them. It’s similar to cortisol. Your body realizes that cortisol is ineffective at reducing stress, so it stops producing as much. This is a late-stage response that occurs when your body’s been very stressed for a long period of time. Signs you may have low cortisol levels include:

• Changes in your skin
• Feeling fatigued often
• Muscle weakness
• Loss of appetite
• Low blood pressure 

Blood vs. salivary cortisol levels

Blood cortisol is only a snapshot in time. If your blood test results suggest you have high or low cortisol levels, it could be from a recent event. For example, if traffic on your way to get your blood test is bad, and you’re going to be late, that could show up as high cortisol. It’s not a good indicator of whether this is an acute or chronic stress level. So if you have an abnormal blood cortisol level, it’s best to follow up with a salivary cortisol test. 

A salivary cortisol test is done by your doctor and includes spitting into a test tube several times over the course of the morning to see how your cortisol levels change, rather than just what one level is. Urinary tests are also available.

How athletes can reduce stress levels

Many athletes are very stressed for a variety of reasons, so here are some suggestions to help you chill and support healthy cortisol levels:

• Avoid fasted workouts (especially for women!), have some simple-to-digest carbs (liquid is fine if working out soon after eating/drinking)- think a few sips of juice, sports drink, smoothie, etc. 
• Eat every 3-4 hours throughout the day.
• Eat within 45 minutes of finishing a workout or race (even if you’re not hungry)
• Take at least one recovery day per week (nothing more than easy yoga, stretching, or a walk) – read why rest days are important for athletes.
• Gradually increase training load, and avoid large increases in intensity or volume.
• Eat enough energy, especially carbohydrates
• Go for a walk
• Be in nature
• Talk to a friend
• Watch a funny video 
• Listen to your favorite music
• Journal
• Meditate
• Stretch
• Do yoga
• Take a nap
• Aim to get more sleep
• Avoid consuming large amounts of caffeine 

Should athletes be concerned about cortisol levels?

Cortisol is an important hormone produced by the adrenal glands and plays many important bodily functions. It’s essential for athletic performance and overall health. Avoid having too much or too little cortisol by managing training, nutrition, and psychological stress. 

Dr. A’nna, Chief Research Scientist at Athlete Blood Test

Dr. A’nna strives to inspire people to optimally fuel their bodies to achieve their best and positively impact the world. She has combined Ph.D./RD specializing in sports performance nutrition with all Ivy League degrees and is the Chief Research Officer at AthleteBloodTest.

Dr. A’nna aims to cultivate a world of healthy athletes who understand nutrition and know how to leverage their physiology to get the best results in sports and life. You can reach her at [email protected] or on Instagram @drannaroby.