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The Role of Hormones in Athletic Performance

No matter our chosen sport, in the quest for athletic success, we all have the aim of maximising our potential. If you’re an endurance athlete, then your training will be focused around building a strong cardiovascular system and optimising energy efficiency. If you are a strength athlete, your training will be quite different, focused more on muscle hypertrophy and power.  In order for our training to be effective, our bodies must respond to the training load placed upon it in a positive way. It is the body’s internal mechanisms that bring about change and progression. And this is where hormones come in.

We spoke to Dr Nicky Keay, an expert in Sports & Exercise medicine, to find out more.

Hormones – the Driving Force of Training Adaptation

What are hormones? Hormones are simply chemical messengers, which are released by your endocrine glands throughout the body, and are transported in the blood. Once the hormone arrives at the cell, it finds the cell’s receptor and ‘docks’, before moving to the DNA in the nucleus of the cell. Once there, it influences the production of specific proteins.

Hormones facilitate the type of adaptation to exercise, such as stimulating certain proteins for building muscle, or synthesising enzymes which improve the handling of glucose in a cell, and are crucial for endurance.

Dr Keay explains: “The adaptations to support improved fitness actually occur after exercise, during recovery. This is why rest and recovery is such an important part of any training schedule. It is only during these periods of rest that hormones are released. They backup and drive the longer-term adaptations for both endurance and power athletes. Hormones are not only key for health, but for athletic performance as well.”

To maintain an optimal hormonal response, balancing the 3 key elements of fitness-  nutrition, training load and recovery –  is crucial.

In order to keep the levels of hormones circulating in the blood at an appropriate level, a feedback loops exists. The circulating hormones tell the brain whether more/less/equal activation is required. With such an intricate and dynamic network, you can appreciate that if you overload your endocrine system, be it with heavy training, lack of recovery or poor nutrition, then things can get out of sync and you will be not be able to train and compete to your full potential. Monitoring key hormones with biomarker tracking can therefore provide you with valuable feedback

What are the key hormones for an athlete?

GH – Growth hormone – This hormone supports healthy body composition and bone health. You can optimise your natural GH production easily, as two of the main stimuli for GH release are sleep and exercise. 

Thyroxine – This hormone regulates rate of metabolism and bone health. T4 is converted in the tissues to the more active T3. Overtraining and/or low energy availability can lead to suppression of T3.

Testosterone and Oestrogen – The sex steroid hormones are released by the ovaries or testes. The ovaries produce oestrogen, which has an important beneficial effect on bone and cardiovascular health (and is why, when women reach the menopause, both bone and cardiovascular health can become more fragile). In the case of insufficient energy availability, young women can effectively become menopausal, with an increased risk of bone stress injuries.

In men (and to a lesser extent, women), testosterone supports lean body composition and bone health. Similarly to women, in the case of low energy availability, low testosterone will occur, increasing risk of injury.  

Cortisol – Another hormone of particular importance to athletes is cortisol. This is released in a diurnal pattern: in other words, higher in the morning and lower during sleep. Overtraining, low energy availability and/or other causes of stress can disrupt this diurnal pattern of release. Not only can this lower immunity, this pattern has an adverse knock-on effect on the hormone systems described above. 

Your hormones are crucial not only for health, but for supporting your athletic performance. 

How to test your hormone levels

The hypothalamus located in the brain controls the endocrine system. It acts as the gatekeeper, integrating internal messages from the body and external factors such as exercise and sleep to regulate the release of hormones from the pituitary gland.

The hormones from the pituitary gland travel round the body to the endocrine glands – such as the thyroid, adrenal, ovaries and testes.

These glands release hormones such as thyroxine, cortisol, oestrogen and testosterone respectively in the blood stream, all of which can be measured with a simple finger prick blood test.

In the blog about hormones and athletic performance, Dr Keay will discuss what happens when hormones are not supporting your athletic performance and how you can recognise the signs.


  • Sports Endocrinology – what does it have to do with performance?
  • British Journal of Sport Medicine 2017
Written by
Dr Nicky Keay (BA, MA (Cantab), MB, BChir, MRCP)

Dr Keay is a specialist in Endocrinology and Sports and & Exercise Medicine. Since completing her degree at Cambridge and clinical training at St. Bartholomew’s Hospital, she has undertaken extensive clinical and research work in Endocrinology and Sports & Exercise Medicine. This has included the effect of training and nutrition on the Endocrine system as well as being part of an international team working to develop testing to detect doping in athletes. Dr Keay is currently working with Forth Edge on a study investigating the bone health of male cyclists.

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