Periodization and Responses to Training Stress
Strength and conditioning programs can bring about significant strength gains, but adaptations to any program is inevitable, so periodization is the concept used to help design and schedule a program that will continue to elicit physical growth and changes.
Canadian endocrinologist Hans Selye has since attempted to explain the benefits of periodization by using the General Adaptation Syndrome (GAS) which can be seen below.
During the next phase, also known as the resistance phase, the body begins the process of recovery and repair. During the stress or alarm phase, the body is broken down and therefore must be repaired, that is where the resistance phase comes in. The body recognizes that the stress that was placed on the body needs to be reversed, and then some, so it rebuilds its tissues to be stronger than it was before. This is known as "supercompensation".
If, however, the same stresses are placed on the body for an extended period of time, an exhaustion phase could be reached. This is where the individual may see a return of some of the symptoms experienced in the alarm phase; soreness, fatigue, etc. There is also the potential for staleness, overtraining, and other maladaptations to occur. Not only can a stale exercise program cause overtraining but lack of sleep, poor diet, and excess mental stress can also lead to these conditions.