The aim of any serious resistance training is to promote tissue growth by increasing the amount of anabolic hormones released into the body. These include: testosterone, insulin, growth hormone and Insulin-Like Growth Factors. Conversely, catabolic hormones are the last thing we want to encourage when we are engaged in resistance training. The main hormone is cortisol, which contributes to the breakdown of muscle protein to be used for glucose synthesis.
Cortisol can be thought of as enemy number one in high intensity training, and thus needs to be avoided. Cortisol also plays a role in suppressing the immune system, which has a negative effect on the recovery and remodeling of muscle. The reason being that cortisol is an extremely catabolic hormone that helps convert amino acids to carbohydrates when glycogen levels in the muscle are low. It is vitally important for survival circumstances, but for resistance training it limits muscle protein synthesis, and therefore muscle growth.
The major problem with limiting cortisol is that the same resistance training protocols, short rest periods and high training volume, that promote GH release, also increases cortisol. This paradox can be alleviated substantially by consuming a higher protein diet, as well as obtaining sufficient rest between training sessions. This rest should include at least eight hours of restful, or uninterrupted sleep per night.
As you can see it is not easy to obtain an anabolic state while limiting cortisol. To reduce the release of cortisol a quality diet of carbohydrates, as well as protein before and after each workout is essential to help promote testosterone, growth hormone, Insulin-Like Growth Factors, and Epinephrine levels. A high protein diet will also help to encourage our body to remain in an anabolic state. Always remember to vary your workout routine in order to prevent the chronic catabolic responses that can occur when too much cortisol is released, often the result of overtraining.