Endocrine System Effects On Training And Performance | Testosterone, Growth Hormone ETC.

We have all experienced fatigue due to stress from training. It may be because we worked out too hard or for too long without giving our body time to recover. But what we do not understand is how this happens and how we can manipulate our training to help optimize our performance and prevent overtraining and unscheduled overreaching.

Our endocrine system helps us get back to a homeostatic function to help respond to external stimulus. It tells our body to make certain changes to help support the demands of exercise and recovery. This system is important because it can help proper periodization for individuals.

Resistance training stimulates multiple hormones like testosterone, growth hormone, insulin-like growth factor, cortisol and multiple cathecholamines. To have proper training adaptation and continued progress optimization of these hormones may help boost training progressions.


Testosterone is the primary androgen hormone interacting with skeletal muscles. There is an indirect marker of motor unit activation and metabolic demands when there is an increase in testosterone concentration. The importance of circulating testosterone concentration for anabolic signal is the binding to its receptor which is key to stimulating anabolic function.

This hormone is responsible for GH responses that leads to synthesis of new proteins and an increase in strength and size. For this to happen high bound testosterone are needed in the blood to increase the potential for higher levels of free testosterone. For testosterone to interact with target tissues there must be free testosterone in the blood.

In women, they have significantly less testosterone compared to men, around 20 times less. Increase in testosterone post workout have not been seen but researches suggest that if there are some changes they are very little. But women who train with heavy resistance does increase but not as much as men. This can also vary per person as some women may secrete more testosterone compared to others.

How does testosterone affect training and performance?

It has been shown that a high intensity training with one to two reps at a lower volume may not change concentration of testosterone but can increase binding sites to testosterone and the number of receptors. On the other hand, an increase in catabolic tissue response can increase in testosterone during high-intensity aerobic endurance exercise. Although aerobic endurance can increase testosterone concentration, it can decrease muscle fiber size.

An increase in testosterone occurs in response of an exercise protocol. The cells then increase binding sites for testosterone to be utilized or due to the lack of need for testosterone use the binding sites to not increase testosterone utilization.

To increase concentration of testosterone in the blood, training and experience may be an important factor to alter testosterone concentration. Testosterone also influenced the nervous system through neural adaptations for strength gain in highly trained strength and power athletes.

Growth hormone