Understanding muscular imbalances

If there’s a concept that has helped me to prevent injuries over the years, is that of muscular balance. Even though I knew about its power, some days ago I was shocked when my dad got out of physiotherapy and with “just some stretches and strength exercises”, he saved his shoulder from surgery.

So the concept works, but many people are still skeptical about it or don’t clearly know what it means. Even though the side of rehabilitation should be guided by a professional, I believe prevention can and should be assumed by each person. That is why this article will teach you what are muscular imbalances, how to detect and treat them.

What is muscular balance?

In the words of Charles Poliquin, it “refers to the major muscles of the body being in balance with each other. This means the balance between opposing muscle pairs (such as the biceps and the triceps for the arm, and quadriceps and hamstrings for the legs) and also between the limbs (such as the right and left leg)” (Poliquin principles).

One thing I would add to that definition is that muscular imbalances can occur in the frontal plane (between the front and the back part of the body, like the abs and the lower back), in the sagittal plane (between the left and right sides of the body, specially in the extremities), and in the transverse plane (between the upper and the lower body).

Three planes for muscular imbalances

If you add to those considerations that any muscular imbalance can be around strength or flexibility, and that it has a local effect on the joints, and a global effect on posture, what you get is a huge concept that explains many musculoskeletal problems. Actually, muscular balance is just a part of a greater concept called Structural Integrity, which will take us some other article to explain in depth. But we have to start somewhere, right? Let’s start with tonic and phasic muscles, which are the key to understanding all this.

Tonic and phasic muscles

All muscles can be divided according to their level of tone. Muscular tone is the level of continuos contraction a muscle exhibits, or its ressistance to passive stretch during rest. So if you lie on your bed to rest and your neck is all tense, you know those muscles have a high tone.

A tonic muscle has high muscular tone, and a phasic muscle has low muscular tone. Therefore, the most common definition of these two is:

Tonic muscle: A muscle that tends to be short and tight.

Phasic muscle: A muscle that tends to be long and weak.

So, whenever you see somebody with rounded forwards shoulders, you now know what’s going on: the front part of the shoulder is tonic, and therefore it is pulling the shoulder forwards from the back of the shoulder, which is phasic.

ozdDQ1IfQqCbfPiapRUH_upper cross syndrome.jpg
Upper Cross Syndrome

Another example would be if you have caved in knees. Assuming the problem does not comes from the hip, which is the usual, what you have here are tonic adductors (inside of the tigh) and phasic abductors (gluteal muscles).

How to detect muscular imbalances

Whenever there is a tonic muscle, what happens is that the muscle is being overly activated by the nervous system, and thus its action is increased. So if the function of the quadriceps is to extend the knee, tonic quadriceps may cause hyperextended knees.

On the contrary, a phasic muscle is under activated, so it lets the tonic muscles pull the joints out of its proper anatomical position. So in the case of a hyperextended elbow, you know the biceps are not doing their job of flexion.

You may dowload this excel table with some of the most common muscular imbalances. This is by all means a simplification, but use these examples to understand the principle behind them, and don´t get lost in details (which are lacking). Understanding this concept will really be an eye opener for many problems you might face.

Tonic and phasic muscles

How to treat muscular imbalances

So, from these considerations, the answer seems clear: you need to reduce the activation of tonic muscles, and increase that of phasic muscles.

How do you do this? Well, even though I will add more to this on the next posts, the standard approach is to stretch the tonic muscles, and strengthen the phasic ones.

Actually, if you train, the best way to do this is to passively stretch the tonic muscles in your warm up, and then strengthen the phasic muscles in your cool down. This is an argument against solely dynamically stretch in your warm ups, because what passive stretching has shown to do is to reduce the neural drive or activation a muscle has and, if not taken care just before we train, our work out will just perpetuate our muscle imbalances.

One example of this over activation is when you see someone doing rows and their neck is shrugging. Bad habbits, tightness, too much weight and lack of awareness causes this, and what you end up is with somebody having their shoulders all up in the air. This becomes a cronic problem, meaning it’s not only present during the action of those muscles, but even during rest.

So now you know what to do: stretch the muscles that are tight, and strengthen those that are weak. It will not only prevent injuries, but help your posture, aesthethics, performance and longevity in the long run.

If you’d like to know more about these topics, I reccomend the work of Vladimir Janda and Florence Kendall 


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