Hans Selye (1976) a Canadian physician, stated that exercise (like resistance training, etc) can be considered as a good form of stress called ‘eustress.’ This good stress allows the human movement system to adapt over time and maintain equilibrium in the body under a variety of conditions.
This is the essence of training progression: the body must experience some form of a stressor that causes the body to respond by adapting to that stress.
Selye indicated that there are three stages of response to stress:
1. Alarm Reaction
2. Resistance Development
The Alarm Reaction Stage is when the body allows different physiological and psychological responses to stress, with the purpose of protecting the body. During the first sessions of a resistance training program, the body tries to adapt to the weight load on the bones, joints, ligaments, and muscles. Blood flow and oxygen supply is redirected to the working muscles, and the nerves recruit more muscle fibers to work.
Before beginning resistance training, the body may be inefficient at responding to the load carried during exercise. By applying the Principle of Progressive Overload, the body gradually increases its ability to exert the necessary responses to the stress placed on it. A good way to observe this stage is through the DOMS (Delayed Onset of Muscle Soreness) – the muscles, ligaments, and tendons are still trying to ‘fix’ itself according to respond properly to the work placed upon it.
During the Resistance Development Stage, the body starts to increase its capability to respond to eustress. Muscle fibers are properly recruited, and blood flow and oxygen supply to the working muscles are efficient. When adaptation has occured, the body then will need a higher amount of stress or overload to produce a higher response and a higher level of fitness.
For resistance training, there are many ways to increase the stress on the body. Most Gym trainers only add weight to the usual amount that a client carries which would result to exhaustion or plateuing. The repetitions, sets, intensity, length of rest periods, type of exercise, etc can be altered to produce the desired progressive overload.
On this phase, the same amount of work load would not result to DOMS and there will be less soreness which would allow the client to increase performance.
If the stress placed on the body is not carefully programmed (sudden overload, overuse, inadequate rest period, etc) training could result to the Exhaustion Stage or distress. This would lead to injuries such as fractures, strains, acute or chronic pains, and even emotional fatigue.
Periodization is important to avoid this stage in exercise training. Any kind of training, whether resistance, endurance, power, etc should be cycled through different stages that provides the necessary loads for sufficient adaptation while allowing enough rest and recuperation for the body. If a training program is not periodized, Overtraining syndrome would occur especially when the body is subjected to continuously increasing amounts of stress without enough rest and recovery. Overtraining is shown by decreased performance, fatigue, loss of appetite, decreased immunity, hormonal disorders, disrupted sleeping patterns, and even mood disturbances.
Simply put, too much of the good thing (eustress) can be detrimental.
Periodization of training allows the specific adaptations in the body to happen while progressively increasing the load by dividing the training program into small cycles that allows for enough rest and recovery to the working muscles. This also helps the client/athlete reach his/her desired goals to improve performance. For the athlete, a periodized program would have a well-planned schedule that coincides with the athlete’s next competition. For the regular client who just wants to stay fit, his/her periodized program would be composed of different cycles throughout the year (or through the time spent with the trainer/coach) that varies the types of exercises, reps, sets, and rest periods to accommodate the desired goal without overtraining the body.
*Note (12/05/2013): I will write more on Periodization as soon as I’m done packing and flying next week. 🙂