Postural and Phasic Tonic Muscles: Which to Train and Why?


In modern concepts of muscle training, those who work in the fitness sector are well aware of the importance of framing structural features of a subject, in order to plan a training as profitable as possible and with the minimum of risk.

In resistance training (resistance training), in bodybuilding in particular, we try to optimize muscle growth and power, using the most effective and varied methods.

Weight training, however, often proves to be a "forcing" on growth some muscles which, due to phylogenetic factors, have assumed characteristics such as not to marry modern concepts.

The fact remains that a bodybuilder, to aspire to his maximum in terms of results, must "grind" hard and intense workouts such as to allow the increase of cross section muscular (hypertrophy).

Body Balance VS Agonism

Having said that, a basic question needs to be clarified immediately: the hypertrophy of some districts DON'T is always functional. It matters little to the bodybuilder, who trains them anyway.

An immediate example can be that of ischio-crurali which, at least in knee flexion, are not used so exasperatingly in any sport. Yet, in the gym they are trained almost exclusively with the leg-curl, as if they had to prepare only for that movement - little or not at all functional. This exercise also has an open kinetic chain and, by definition, has almost nothing to do with the movements that an individual performs in daily gestures.

In "stage" bodybuilding this is fine, because the primary objective remains the hypertrophy to be shown in the poses. The athlete makes a choice on the right risk / benefit ratio, shifting the balance towards the "benefit" and neglecting (often deliberately), or not taking care, the "risk" parameter. For what concerns the competitive spirit, this can have "right", condemnable or not, because an athlete must reach the goal (almost) at any cost.

For all the others, however, the reality of the facts is different. Staying in the area of ​​"well-being" one should understand what the body needs, and not let any muscle grow to the maximum.

It should therefore be understandable that sport and fitness, but even more wellness (or its evolution), are reality very different between them.

Below we will try to understand how to train a subject that DON'T has ambitions competitive, dedicated only to fit-wellness, therefore to general psycho-physical well-being.

Tonic-Postural and Phasic

Different types of muscle fibers

Distributed throughout the body we find muscles which, by composition, shape and function, are different between them (long, wide, short, annular, orbicular, sphincter, single-headed, biceps, triceps, quadriceps, etc.).

Basically, the properties of these muscles - including the composition of fibers - are the result of a phylogenetic evolution that has produced the current human musculoskeletal system.

Neurologically, muscles contain three: types of fibers, activated with discharges lens (type I) or veloci (types IIa and IIb).

Note: IIa are also called intermediate, because they have the ability to specialize in one metabolic direction or the other, even if they retain a greater aptitude for type II.

The lenses exploit energy metabolism mainly oxidative, presenting a high concentration of myoglobin it's a capillarization denser, which gives them a hue red.

Fast fibers, on the other hand, use a metabolism mainly glycolytic and have a low threshold of tolerance to fatigue, possessing a poor network of capillaries which gives them the typical more clear.

What are the tonic-postural muscles?

The muscles with prevalence of these fibers are classified as muscles tonic-postural. In case they are in a state "dysfunctional", they manifest the state of suffering determining a condition of shortening e stiffness.

What are phasic muscles?

Muscles that predominate in this type of fiber are classified, based on their function, as muscles phasic. They manifest their status "dysfunctional" weakening.

To clarify the above, it should be noted that each muscle contains a combination of the various types of fibers, but in some areas there is a predominance of one over the other.

What are the tonic-postural muscles?

Those that perform a function mainly tonic-postural are, starting from the bottom upwards: gastrocnemi, sartorius, ischium crurali, ileus psoas, rectus femur, tensor fascia lata, adductor and piriformis group, complex of the erector muscles of the spine and in particular, at the cervical level and lumbar, the square of the loins and the scalenes. In the shoulder girdle are the pectoralis major, the elevator of the scapula, the upper trapezius and the brachial biceps.

What are the phasic muscles?

Those that instead perform a function mainly phasic, therefore of movement but DON'T sealing, are: anterior tibialis, vastus medial and lateral, medium, large and minor gluteus, perineal muscles, erector muscles of the spine in the thoracic-middle portion, rhomboids, lower trapezius and brachial triceps.

For many scholars, understanding the distribution of fibers in the others body muscles (not mentioned) is not as clear; perhaps because the composition is probably so mixed and heterogeneous that it prevents us from establishing a true dividing line in terms of classification.


It is in the tonic-postural muscles that the most pain-problems typical of modern man: sense of stiffening, feeling of "strung", etc.

But why? Simply because those muscles they react to a problem above all stiffening e shortening.

In summary terms, at this point, the tonic-postural muscles could be defined as that complex of muscles that "keeps us on our feet", counteracting the force of gravity, continuously maintaining balance and managing the center of gravity in the base polygon without interruption. .

The phasic muscles, on the other hand, are those that allow us to lift loads, push one object or pull another; therefore to perform movements of force and not of duration.


From what has been said above it can be understood how the tonic-postural muscles work practically always (15-16 hours a day), or at least every time the standing or sitting position is assumed.

By also applying physical exercise for hypertrophic purposes, there is a tendency to retract and contract them further, causing chronic pain, altered postures, various imbalances and, last but not least, joint compressions.

This happens because the long-lasting activation of abnormal joint reflexes (joint stress), determines a change in the memory of the Central Nervous System: from a condition of equilibrium one passes to a state of abnormal adaptation, giving rise to muscle decompensation.

This decompensation is generated by the SN which "badly manages" the coordination of agonist-antagonist activities on the peripheral systems.

As a result, various muscles react by stiffening, while others weaken, due to abnormal work.

The solution is almost always a different active work, designed to establish a body balance that allows our muscular system to be efficient with minimal effort.

What remains necessary, however, is to understand which exercises should be performed or avoided in the non-athletes.

Training of Non Athletes

How to train non-athletes?

Above we have listed the phasic muscles that would be worth strengthening, especially in those subjects who do not practice any form of continuous training, and the tonic-postural muscles, which instead should be made more flexible because they tend to be retracted.

This, logically, is not a real general rule; as always, each subject should be subjected to test specific.

In general, however - with the exception of top level athletes or sportsmen - and "non-athletes" certain exercises should be avoided in order not to run the risk of changing themuscle balance.

In these cases, therefore, it would be more appropriate stretch "stiff" muscles and strengthening those that appear "weak" - creating functional compensation.

They should be used marginally - or maybe even abolished - certain exercises such as calf, leg-curl, hyperextension, sit-up, curl, abductor machine, lateral torso flexion, shrug or curl, because they are responsible for soliciting the already heavily stressed muscles for most of the day.

The main problem is that "who goes to the gym" DON'T necessarily seeks to improve his own postural condition, but she is dedicated to aesthetics, to harmonize her body and reduce that damn excess fat.

To personal trainers, we recommend improving communication with customers, trying to make them understand the importance of to balance the musculoskeletal system not only from an aesthetic point of view, but also and above all for a condition functional.

Hence, even in a wild pursuit of aesthetic improvement, it is good to choose more exercises productive from a "daily utility" point of view, such as squatting, lunges in progression, push-up, pull-up o rematoria, exercises of stabilization, proprioceptive etc. Not just gluteus machines, abductor and adductor machines, leg curls, tons of crunches and more.

And if the customer were to "put his foot down", there wouldn't be much to do. There will always be the "hairdresser" who wishes to develop delts and trapezius, ignoring the stress suffered by the humeral bachelor and rotator cuff over the course of the day.

If so, it will simply try to minimize the damage by managing the exercises, the ROM, the load ... omitting as much as possible certain guidelines that, if on the one hand Mr. Olympia could not ignore, to the subject in question could cause not negligible damage - especially in the chronic.

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