What Is Cortisol?

Cortisol is a hormone that belongs to a family of steroid hormones known as glucocorticoids. It’s secreted by the adrenal cortex, which is located in your adrenal glands that are positioned above your kidneys.

Glucocorticoids affect every cell in the body so needless to say, they’re very important.

Cortisol can often be viewed as a ‘bad’ hormone but it plays a vital role within the body. It is involved in our metabolism, immune function, hydration levels and blood sugar balance. However, it is the ‘stress’ response within the body that cortisol is most associated.


With short, acute periods of stress, cortisol accelerates the breakdown of proteins into amino acids. These amino acids move out of the tissues into the blood and liver cells, where they are changed to glucose in a process called gluconeogenesis.

This speeding up of the metabolism and the blood and sugar balancing that goes alongside it are essential responses to stress. Partnered with the immediate anti-inflammatory effect the body is in a much better place to deal with short term stress.

Over longer, chronic, periods of stress this cortisol response has a greater negative effect and will encourage inflammation in the body, increase fat storage and suppress energy levels. Over an extended period of time this can lead to Cushing’s Syndrome which include the following symptoms:

  • Rapid weight gain in the face, chest and stomach
  • A flushed and rounded face
  • High blood pressure
  • Osteoporosis
  • Joint pain
  • Muscle weakness
  • Mood swings, depression and irritability
  • Increased thirst and frequency of urination


Exercise can have a very positive effect on cortisol levels.

Short intense bouts of exercise will have a positive effect on your growth hormone and testosterone, which creates a positive controlling influence on cortisol.

However, during more chronic periods of stress your heart rate recovery will be slower and therefore understanding and monitoring recovery levels is vitally important.

Shortened high intensity workouts with controlled recovery to a pre-determined recovery point works well to create a positive dopamine effect, recover energy and tackle stress. Longer periods of high intensity work with unmonitored recovery will lead to exhaustion and increase the negative stress effect.

Medium intensity long duration endurance training has an increased cortisol effect on the body. During periods of extended stress this style of training is not advisable, unless you are training specifically for an event and even then it should be questioned whether it is the right time or event to take part in if you have some stress indicators already showing.

When you feel stressed training smart and getting immediate energy and confidence uplifts is extremely important. Not training because you feel tired or low is never a long-term answer.