- 4 Jul 2011
By Matthew Perryman
This is a basic introduction to periodization. Nothing fancy, nothing extravagant, just the basics outlined for those new to the topic.
Fundamentally, the body is an adaptive mechanism. In other words, you impose a stress upon it, and the body will respond to lessen the disruption caused by that stress. Bear in mind that the body is nothing more than an amalgamation of cells programmed to work together. In turn, these cells are essentially packaged biochemistry, a means of transforming chemicals and energy into different forms.
Like any machine, living cells have a limit to how much stimulus they can tolerate before they degrade or become damaged. However, unlike a machine, living cells have an ability to not only compensate, but supercompensate for that damage. This is the basis of all physical training—to stimulate the tissues of the body with the end goal of forcing an adaptation.
Super-compensation and Fitness-Fatigue
The body is a dynamic system designed to adapt to stimuli, which in this case is physical training. This stimulation and adaptation process can be described by a basic wave. The body’s state starts at a baseline and then declines as stress is added. When given the opportunity to recover, the body’s state will begin to increase back to the baseline (compensation) and will continue to increase past the original baseline (super-compensation). If not stimulated again, it will start to decline back to the original baseline (detraining).
The super-compensation model also postulates two other possibilities. If an additional workout is performed before the body supercompensates, the state will start a downward trend. If this keeps up, eventually the body’s reserves are depleted and the so-called overtraining syndrome sets in. On the other hand, if another workout is imposed at the cusp of super-compensation when the body is fully restored, then the process repeats and the body reaches yet another higher state. Obviously, the latter is the goal of training while the former should be avoided. In a sense, the super-compensation model is accurate, but it leaves out some critical information that can affect the prescriptions coming from it.
The more accurate fitness-fatigue model expands upon the super-compensation model. The super-compensation wave still exists, but it is the summation of two separate indicators—the fitness state and the fatigue state. According to this model, any training stimulus (i.e. workout) creates both positive (fitness) and negative (fatigue) aftereffects in the body. The fatigue effects mask the fitness effects, creating the short-term performance drop-off that is observed after a training session. However, the fitness effects are maintained by the body for a longer period of time than the fatigue effects. This leads to interesting new ways of organizing training to exploit this fact.
Instead of placing importance on fully recovering and supercompensating from each individual workout, the emphasis instead shifts towards accumulating fatigue over time, which also allows a greater accumulation of positive fitness gains. The fatigue can then be dissipated with rest while the fitness gains are retained. The idea is to plan progression over longer phases as opposed to trying to gain from session to session.
Remember though that the fitness-fatigue model doesn’t replace the super-compensation curve. It simply defines it as the summation of both positive and negative effects on the body. In other words, the super-compensation wave applies to a period of weeks or months instead of a period of days as it is normally used.
This theory also postulates that different types of sessions have differing effects on the positive and negative factors as opposed to the simple fatigue aftereffects of the super-compensation model. Not all training is created equal. High volumes of work create a less pronounced effect on fitness and fatigue, but one that lasts longer. Conversely, high intensities of work create a very strong effect on both, but the effect is short-term and delayed.
Basically, this means that you have to pay attention not only to the acute effects of training but to the aftereffects of this training as well. This is the essence of periodization. It applies not only between single workouts but between phases of training and even in a workout session. This is important to remember as it has critical implications.
The Training Load
The training load is the stress applied to the body to cause adaptation. It is typically defined by volume (the amount of work) and intensity (the magnitude of work). For all intents and purposes in strength training, volume is the number of reps done while intensity is the weight used. The tonnage (or total training volume) is the number of reps multiplied by the intensity. Although far from complete, it is generally a good way to measure the overall effect on the body
The content of the training load is just as important as the volume and intensity of the load. Content includes everything else about the load such as exercise selection, speed of movement, rate of force development, rep range, muscle action, rating of perceived exertion, and so on.
Stress, then, is a result not only of volume and intensity but of what is being trained and how it’s being done.
For example, compare a maximal squat to a high-rep set of leg extensions. Both use the musculature of the legs, but the commonality stops there. The maximal squat is an all out exertion of relatively short duration. Make no mistake—it makes use of the musculature. However, the primary stress is imposed on the nervous system, which is working overtime to make sure that the musculature is moving the load. This is contrasted by the leg extensions, which use higher reps, more time under tension, and thus involve more of the tissues of the quadriceps. In fact, unless the set is taken to muscular failure, where each rep requires a concentrated mental effort, the neurological stress is minimized and instead the muscle itself is the focus of the stimulus.