Cortisol is commonly associated with being bad for your body – you probably know it better by its alter-ego ‘the stress hormone’ – mainly because it’s released when you’re stressed – and for its catabolic influence on muscle tissue. However, just like every hormone it has positive and negative influences on your body. It’s only when an imbalance occurs that the downsides begin to overshadow the benefits. Without cortisol it’s unlikely you’d be here to read this article, nor me to write it.
Cortisol is responsible for the stimulation of your sympathetic nervous system (SNS), which drives the fight-or-flight response that primes your for action when your survival is threatened. Without it our ancestors wouldn’t have stood a chance against the ambitions of all those hungry predators that wanted to make homo sapiens supper. And even if they had survived, you’d still not be reading this because you’d be fast asleep: rising cortisol levels – they peak at 8am, and are at their lowest between 12am and 4am – are what causes you to wake up in the morning, get out of bed, and start the day. This is why when sleep patterns are disrupted, there will be an imbalance in normal cortisol cycles.
The other positives of cortisol
Cortisol is a glucocorticoid, or steroid hormone. It is released from your adrenal gland, upon instruction by your hypothalamus and pituitary gland, and its primary role to increase blood-sugar levels (through the conversion of amino acids to glucose), suppress inflammation, and aid with fat, protein, and carbohydrate metabolism.
Cortisol has many other benefits, including strengthening the immune system, blood pressure control, reducing inflammation and glucose management. Another good example where cortisol is important is when training. When you reach the minimum threshold of intensity your body’s response to this stress and stimulus is what induces positive adaptation.
The downsides of cortisol
The biggest issue with cortisol management is the daily stresses we all face in the modern world – work, commuting, relationships, kids, and everything else that requires our attention and action. This can accumulate over time, resulting in your SNS being stimulated regularly without sufficient rest and recovery that is so detrimental to your physical and mental health. So you reach for another coffee to boost your energy levels but like all caffeinated drinks, it causes a small rise in cortisol levels, exacerbating the problem.
Over time and left unchecked, cortisol will adversely affect the functioning of your hypothalamic-pituitary-adrenal-axis (HPA-axis), which will result in depression, thyroid dysfunction, chronic fatigue, decreased immune system among the biggest problems. If you’re struggling with consistently high stress levels and it begins to affect your training and your health, the vital first step is determining the root cause and then limit these stressors to avoid further health problems.
The phases of stress response
There are three main phases of the stress response first described by pioneering Austrian-Canadian endocrinologist Hans Selye in the 1930s as the General Adaptation Syndrome and it’s still a well-accepted model. These phases are: Alarm (or acute stress); Resistance (or chronic fatigue); and finally Exhaustion (or burnout). The theory was developed with an understanding that stress can become a major health concern over the long term by causing chemical changes in your body.
The Alarm Phase (Acute Stress)
Your body’s initial response to stress when a threat is recognised.
Physiological impact Adrenaline, noradrenaline and cortisol are released to up-regulate all the systems needed to deal with the stressor. Cortisol metabolism increases to deal with the response to allow levels to return to a normal range within 24-48 hours.
The Resistance Phase (Chronic Stress)
The stressor remains active so the stress response fails to return to normal levels.
Physiological impact The conversion from cortisol (active) to cortisone (inactive) increases, as does cortisol metabolism in attempt to deal with an overabundance of the hormone. Heightened cortisol levels throughout the day also affect your circadian rhythm, causing sleeping problems and dysfunctions of the HPA-axis, resulting in weight gain, immune system deficiencies and cardiovascular problems.
The Exhaustion Phase (Burnout)
This occurs when the adrenal response diminishes despite the on-going stressor remain active.
Physiological impact The adrenal glands have lost their ability to effectively release cortisol so your body stops metabolising the hormone to try to keep hold of as much of it as possible, as well as diverting resources away from testosterone or oestrogen production. This leads to loss of strength, depression and fatigue along with many other conditions.
Monitoring cortisol levels
With cortisol playing such an important role and the problems that arise if levels fall out of sync, it’s vital you closely monitor your cortisol levels and response. If you are concerned your response is not optimal, then it is well worth getting your levels tested. The three key options are serum (blood), saliva, or urine samples. We prefer urine testing because it is easier to collect over a 24-hour period, and so incorporates the natural variations of cortisol because of the circadian rhythm, and a complete picture of the HPA-axis can be determined from the metabolites measured in the urine.
Cortisol is an essential hormone for the metabolism of fat, carbohydrate and protein along with modulating the immune response and many other important roles. However, it must be managed effectively not least for optimal performance in the gym, and recovery afterwards, but more crucially for good long-term health.