When designing a training programme or even evaluating another programme that you may be considering useful for your goals it is important to understand the scientific principles that guide these decisions.
Training is essentially forcing adaptation of the body to the new conditions. Your body reacts to various stimuli with a huge variety of responses and you must understand which responses are effective for your eventual goals. The resulting goals of a competitive bodybuilder may be at odds with an Olympic level strength lifter and consequently different to a professional Rugby player or martial artist.
Forcing adaptations that suit your primary goals require use of the following principles of muscular development and reaction to stress.
The following principles are not mutually exclusive but generally encompass all the factors that are known to scientifically affect muscular size, strength, speed and skill development. Every training regime, regardless of its intention or philosophy will base itself on one or more of these principles and you will understand far better why by familiarising yourself with these principles first. They will also improve your training understanding in general and aid in the future development of your own regimes and personalised plans.
In brief these 6 principles can be summarised as:
1. Overload Principle
Put simply the body adapts to stresses. The body must experience continually increasing resistance to continue adaptation. Consistent overload states that the body needs to push more to grow more.
2. Isolation Principle
Isolation suggests that in order to ensure stress is successfully aimed at all muscles and optimal development occurs it is best to isolate as much as feasible the muscle being trained to ensure that weaker units do not escape the overload principle.
3. SAID (Specific Adaptation to Imposed Demands) Principle
Individual muscle groups are best seen as a collection of components that react differently to very specific forms of overload. SAID suggests that optimal development can only occur when these individual elements are treated separately and training principles applied to maximize contribution from each.
4. Stimulation Principle
In order to maintain skill forms or integration between muscle groups this principle states that various movement patterns must be forced to experience increasing resistance to enhance the motor development and neurological patterning of those skills and movements. This principle is effectively in opposition to the Isolation Principle stating that integrated movements are the priority over individual isolation.
5. Dis-inhibition Principle
This principle states that training must be aimed at focusing overload on inhibitory mechanisms in the body. With this principle muscle and skill development is seen as limited by various ‘safety’ inhibition mechanisms in the body system and that eliminating or reducing these factors allows greater muscular force to be generated.
6. Accommodation Principle
Especially in regard to finely skilled pursuits this principle states that uncoordinated muscular development or fatigue from various heavy training regimes may negatively affect those skills. In order to maintain a balance between training effect and maintaining skill sets effort must be distributed between both to accommodate both.
Using and understanding the principles:
All routines and training parameters are based to some extent on one or more of these principles from the early Weider bodybuilder programmes to the most advanced periodized plans put forward by modern authors.
Firstly the Overload Principle is virtually uniform in all muscular development programmes, although you will find various parameters to achieving this.
The Isolation Principle is more often found in bodybuilder and physique programmes that require a more symmetrical physical development with less emphasis on overall motor skills and more on developing ‘target’ muscles and weak or lagging muscle areas. These are often described in training regimes which aim to develop a particular look to the physique regardless of actual motor performance. Generally isolation exercises do not build maximal strength or overall co-ordination but do allow careful enhancement of weak muscles, following injuries or for aesthetic reasons. Isolation is often recommended for small muscle groups which are easily dominated by body shape imbalances. This can often be seen in ‘arm’ specific training where the shoulders and upper back are taken out of the equation to give weak arms more direct overload.
The SAID principle is primarily concerned with a scientific approach to maximal development of muscular size, concerning itself with the various cellular and fibre types within muscles and how to maximize these. The SAID principle is often quoted by those routine designers who prefer a background in neurological sciences and see the body as working as fibre types and cellular mechanisms than as simple muscle groups. SAID is often a philosophy behind ‘holistic’ training methods which aim to induce maximum muscle size and strength by hitting every component of muscle with different training protocols, from myofibrils to sarcoplasm. This ‘whole muscle’ approach is keen to max out genetic possibilities by understanding that ‘muscle’ is not just a simple tissue but a collection of many different cells, fibres and fluids all of which can be affected by very different stresses and stimuli.
The Stimulation principle is often a major concern for strength coaches who are attempting to maximize strength and explosive power. These lifts require a specific set of motor skills to achieve maximum results and stimulating the body in a way which develops motor patterns and as an integrated chain as opposed to in an individual muscle group. In this way this principle may also be of more importance to sports coaches. Many modern day coaches often try to teach integration between aesthetics and performance and may include routines which rely on the stimulation principle to inform their use. Although bodybuilders may not find as much use in movement specific training, many people can find less injury and better development for certain body shapes and types than in traditional bodybuilding training. Obviously sports coaches also prefer to teach resistance in the movement of most benefit to their athletes.
The Dis inhibition Principle is an attempt to understand the limitations placed on the body by its safety and inhibitory mechanisms. These are designed to limit performance or rates of change but may often be artificially limiting maximum results. Some training regimes now attempt to use this principle to train the body to remove these obstacles to achieve new levels of power, strength and size development. This principle is quite scientific and requires an understanding of complex limiting factors and genetic ties. Some coaches have found that overcoming natural limitations may be possible by teaching the body ‘new tricks’ or focusing effort into areas that appear to have feedback limitations. This is probably the least explored of the principles but may have a lot of use in expanding training options.
The Accommodation Principle seeks to find a balance between the skills necessary for a particular sport or activity and the requirements for hard training needed to make gains and adaptations by integrating time and recovery for both. Those involved in martial arts for example may require more muscle size and strength but not at the expense of learning complex skills and maintaining complex motor patterns whilst avoiding fatigue. This principle is often used to keep the fitness of competitive athletes at maximum while still improving overall performance. Accommodation would also manage the reasoning behind training for extreme fat loss whilst maintaining muscle mass. It is often difficult to train for extreme size whilst keeping recovery high enough and at the same time shredding body fat away. This may involve complex accommodations to manage both goals without causing injury or overtraining or loss of skills and necessary sports specific motor actions.
These principles are not mutually exclusive and you may find training regimes which attempt to invoke several in order to achieve maximum results in a particular area or for a particular type of athlete.
More on the General Overload Principle
Regardless of what training routine you employ or overall goals you wish to achieve the principle of overload is universal. The human body is a highly complex machine with multiple systems designed to help it adapt to stresses and stimuli in order to become more suited to survival and success. Your body generally wishes to remain in a state of homeostasis (lit. to stay the same). Building new muscle or acquiring new skills may lead to a better chance of survival or success but all of this will require an input of time, energy and require greater resources and more food and rest etc. In order to convince your body’s systems to develop a new form you must apply a stress which the body will adapt to. This is the basic principle of overload. When you lift a weight for more reps or using a higher load than previously you set in motion a chain of adaptive reactions which cause your body to undergo a training response. Presuming you have access to enough nutrients from food and enough time to rest and recover your body will adapt to this new stress by repairing the minor damage inflicted on the body and build a slightly stronger or bigger muscle or more efficient neural or hormonal response. Overload states that you must continually raise or alter the stress or stimuli on the body to achieve a new adaptation.
Simply lifting the same weight in the same way for the same amount of time will not cause an adaptive response since the body already knows how to accommodate these stimuli. Each time you train or perform your sport you will see the most development if you overload your system to some extent and see a new stress that the body must learn to accommodate.
Overload is the reason why training protocols generally increase one or more parameters. These can include the amount of weight lifted, the time taken to lift the weight, the amount of rest taken between sets, number of sets and number of reps amongst others. You can read more about these training parameters and other forms of overload in the Periodisation article. This definition of overload is not the only one used and is the broadest possible description of the principle itself.
A more definitive method of overload is often known as extension sets and protocols.
These are a number of ways to induce overload and these are often credited with originating in the bodybuilding world under the Weider principles. Although often refined and re-described it is possible to see evidence for these in almost all of today’s ‘extension’ sets and methods. As most training initially followed the limited volume and very limited exercise selection of early power training forms, many of these ‘overload’ principles were new at the time of introduction and were designed to bust through ‘plateaus’ and stop muscle development stagnating due to lack of variation.
The Weider principles include such techniques as split training where the body is broken up into muscle groups or movements and these are trained on different days or in different training sessions on the same day. These principles then became more complex and involved such programme overload designs such as supersets (two different exercises for the same body parts or antagonist body parts performed without rest in-between) giant sets (same as supersets but three or more exercises used together) and muscle confusion principles. This system predicted that constantly changing parameters would confuse the body into adapting to many various stresses and be unable to get comfortable adapting to one simple progression.
You can find a lot of these training principles and techniques described in more detail in the Glossary article.
As simply stated the Overload principle does not take into account any further aspects of training such as nutrition or the possibility of overtraining. Your body must work within the framework of its capability to recover. For further reading on these topics please see the Optimal Nutrition article.