Twenty years ago, the average person did not know what cortisol was. Today, cortisol is as familiar to most of us as other hormones such as insulin, oestrogen and testosterone. To say that the average person has an accurate understanding of cortisol’s nature and functions in the human body would probably be a stretch. Hence this blog!

In the lay public, cortisol is known as a “stress hormone” that is bad for the body. While it is true that the body does release cortisol in response to various kinds of stress, it is important to recognize that our body’s ability to respond to stress is critical to our health and survival! Even the improvements with our fitness that we get through training are a form of stress response. Cortisol’s effects on the body are fundamentally beneficial, except when we are subjected to too much stress. Then it becomes too much of a good thing. But, of course, cortisol is not exceptional in this regard is it?

A bit of biology…

Cortisol is produced by the adrenal gland. Its release is controlled by the hypothalamus, which is a major controller of metabolism located in the brain. One of the main jobs of cortisol is to increase the glucose concentration in the blood to make more energy readily available to the muscles, cortisol manages how your body uses fats, proteins and carbohydrates. As you might expect, cortisol release from the adrenal gland increases at the onset of exercise and remains elevated throughout exercise, when the muscles create a great demand for energy.

The normal effects of cortisol pass quickly through our body, stress occurs, cortisol is released to make energy available, stress ceases, cortisol release goes down, and the body goes back to its normal state. Throughout our day cortisol levels fluctuate, but when stress becomes chronic, the body is continually exposed to high levels of cortisol and long-term negative health effects may occur. Chronically elevated cortisol levels have been linked to problems including abdominal fat gain, decline in brain function, sleeping problems, muscle weakness, mood problems and a lowered immunity. The link between cortisol and weight gain especially — which has been blown out of proportion in some areas of the fitness business, but is real — but it has caused cortisol to acquire a bad reputation. But I want you to start thinking of cortisol as a necessary part of your how your body functions, if our cortisol levels are low, this can also have a very negative effect on us. Some of the side effects of low cortisol levels include dizziness, fatigue, confusion, vomiting, muscle weakness, insomnia, body aches, back pain, anxiety and food cravings to name just a few. Can you see how these symptoms are similar to those associated with high cortisol levels? We need to start thinking of cortisol as our friend that gets us through our day from waking up in the morning, being alert while we drive, walking the dog and so much more.

Some of the highest cortisol surges occur during and after exercise, endurance athletes are exposed to more cortisol than even many of the most stressed-out non-athletes. But do these repeated short bursts of cortisol release really add up to long-term high cortisol exposure in your average gym user and endurance athletes?

German researchers measured cortisol levels in hair to quantify cortisol levels over time in a group of endurance athletes and compared the results to measurements taken from non-athletes. They found that long-term cortisol exposure was indeed significantly higher in the athletes. Does this mean that endurance training is bad for our health, or at least bad in one particular way?

Enough is known about the many positive health effects of endurance training to say without qualification that, on balance, it is extremely beneficial to overall health. And since endurance training has been shown specifically to reduce abdominal fat storage, improve brain function and (except in cases of overtraining) enhance immune function, we can also say that high cortisol levels in endurance athletes do not have the same health implications that they have in non-athletes.

There can be too much of any good thing. Just as cortisol turns from good to bad when produced in excess, endurance training turns from healthful to unhealthful when an athlete over-trains. In the over-trained athlete, high cortisol levels may have negative health effects, but even then high cortisol levels are just one of many imbalances seen in endurance athletes who work too hard and don’t rest enough. There is a common misconception that steady state cardio (doing aerobic exercise on a cardio machine or going for a run of your choice for an hour without changing speed or intensity levels) is good for you, that it helps you loose weight and get lean. This is one of the biggest training myths out there! Here’s why- you’ve heard me talk about skinny fat before- a slim body but no muscle definition- steady state cardio elevates cortisol levels in your body and its this that overloads your adrenal glands, stresses the body, increases insulin resistance and it is this response- this increase in insulin resistance that leads to a craving for carbohydrates because of that drop in ability to deliver energy from our food which leads to an increases body fat particularly around the abdomen.

So what can we do to manage our cortisol levels? There is heaps of evidence out there now that points to the importance of HIIT being the best kind of workout for maximum results,  you cannot ignore the overwhelming evidence with science backed evidence that this is the kind of workouts we all need to be doing. The key thing is to be smart about how we use HIIT to maximize the benefits. Use HIIT training in combination with a strengthening program, include no more than 2-3 HIIT workouts a week, drink lots of water and eat a healthy, nourishing, low sugar diet.

As an average gym user, you don’t need to worry too much about cortisol. Just train smart and your hormones will take care of themselves.