Tag Archives: stress hormone

How long should you train?

Many people think that the longer one trains, the better the results. Although a certain amount of training is necessary, it is possible to train too much or too long. So how long should you train?

One of the factors involved is the amount of glycogen the body still has in store to use during exercise. When the body’s glycogen stores are emptied, it can not sustain a high training intensity and muscle tissue will be broken down to supply the necessary energy.

Normally, the body has sufficient supply for 45-60 minutes of fitness training. In well trained athletes this supply can be increased to 90 minutes. It is therefore important that a training never lasts for more than 60-75 minutes (this time is longer because fitness training allows recovery periods). Sometimes training for a longer period is possible, but make sure carbohydrates are replenished by a sports drink or other fast carbohydrates.

During training the body produces the stress hormone cortisol. When it is produced in large quantities and it can not be broken down because one trains too long, cortisol levels can rise more permanently. This is seen as one of the causes of overtraining, in which performance decreases and recovery from training is slow. An elevated cortisol level breaks down muscle mass, effectively countering the effects of training or even breaking the body down further.


Cortisol, also known as a stress-hormone, is a hormone produced by the adrenal cortex and plays an important role in glucose regulation. Since nerve cells can only produce their energy from carbohydrates and glycogen, when blood sugar levels and glycogen stores are low, cortisol stimulates conversion of protein to carbohydrates. This results in increased protein breakdown and it inhibits protein synthesis, effectively breaking down muscle tissue to produce carbohydrates. Cortisol is secreted during times of stress but high intensity resistance exercise stimulates cortisol production as well. Since resistance exercise also stimulates testosterone and growth hormone production, this is not a negative effect, since these more than counter the influence on hypertrophy of cortisol. In fact, it is believed that cortisol plays an essential role in remodeling muscle tissue after training.