August 9th, 2014 Issue 12

For the next few newsletters we will be featuring various important topics related to NET's strength for health concept. The content of these topics will come from NET's training handbook, titled Full Strength, authored by Werner Kieser. We have the author's written permission to use the content of this book for our educational purposes.

In this issue of NET Effect (note the change of the newsletter name), we will be talking about muscular imbalances. This is an important topic for all of us, especially for those who are 40+. It is almost certain that throughout the course of our life we will develop various muscular imbalances in our body. They could result from participating in a specific athletic activity, like running, cycling or lifting weights, or from having a desk job for many years.

Below, we describe 3 major types of muscular imbalance.

For those who wish to work on correcting those imbalances, try to emphasize single joint over compound exercises, like knee extension vs leg press for example. Try to work the smaller muscles as well, such as C5 (which targets the rhomboids for correcting upper body posture), E4/5 (which targets muscles in the rotator cuff for correcting shoulder imbalance), F3 (which targets the deep extensor muscles of the back for correcting and preventing back pain) or G3-5 (which targets muscles of the neck for getting rid of neck soreness and pain).

When the goal is to correct muscle imbalances, it is especially important to maintain perfect form during the exercise. The body will find a way not to use the weak muscles and to overcompensate with the stronger ones. This only results in making the stronger muscles stronger and keeping the weak ones weak.

Enjoy the read!

NET Team

Full Strength series: Muscular imbalance

Full Strength
Werner Kieser

Our entire muscular system is one of interdependence. A change in the strength of one muscle has a knock-on effect on other muscles. Each of us has our own ideal in terms of muscular balance, the right strength relationship between muscles. The degree to which each of us deviates from that ideal varies but the cause is always the same: those muscles subject to loads above the stimulus threshold (trained muscles) as a result of work or leisure activities, take the load off other muscles that are much weaker. As a result, the latter get weaker and weaker. It is a vicious circle. The resultant imbalance is a very gradual process and at first we do not notice it. It also results in a change in posture. Poor posture is not a bad habit. It is caused by some muscles being stronger than others.

Antagonist imbalance

The mechanics of the musculoskeletal system can be likened to the steering on an aircraft. It consists of tension and countertension. An aircraft has an elevator and a rudder (wings and tail) to move up and sideways and we have bones. Aircraft have cables. We have tendons. Despite its simplicity the human system is prone to problems. Muscles, even at rest have a certain level of tension (tone). If the tone in the agonist differs from that in the antagonist the result is a muscle imbalance, that is, different strength levels. Sooner or later this will cause problems.

Strength training restores that balance by exercising both agonist and antagonist. It would make little sense to stretch only the "shortened" muscle until it was the same strength as its opposite number as that would be a levelling down. What we need to do is to strengthen agonist and antagonist until both reach their strength limit. The weaker muscle soon catches up-the stronger muscle has a much lower growth potential anyway. The closer the two are to their genetic limit the more in balance their strength ratio.

Inter-muscular imbalance

Another type of muscular imbalance is the one found in a chain of muscles. Normally any given movement requires a cooperative effort by several muscles in a so-called chain. If the work required for a specific movement involves several muscles, the relationship between the strengths of these muscles must be right. If not, the result is an inter-muscular imbalance. To eliminate this imbalance, we need to isolate the weaker muscle and then strengthen it. If the muscle is not isolated, the stronger muscle will come to the "aid" of the weaker one. Once the muscle has reached its ideal strength, the muscles are in balance. Experience has shown that once restored the balance can usually be maintained without further training. This is because the new strength ratio changes our posture and the way we move and so the work is distributed more evenly between the muscles.

Those with chronic low back pain are normally suffering from an inter-muscular imbalance. Most of the work to straighten the back is done by two muscle groups: the gluteus maximus and the back extensors. The latter also include the so-called autochthonous back muscles of the spine. In most cases, our back extensors are weaker than our gluteus maximus. Unfortunately, we unconsciously change our posture and the way we move allowing the gluteus muscle to take on more and more of the work of the back extensors. As a result, the latter lack stimulus and become weaker and weaker, a vicious circle. It can only be broken if back extensors are isolated and strengthened: we need to exclude the gluteals.

Intra-muscular imbalance

However, the most common form of imbalance is one within a muscle, that is an intra-muscular imbalance. Even amongst professionals it is still largely unknown because the tools required to diagnose it are relatively new. Unlike the other two types, this imbalance is in the muscle itself rather than in the relationship between individual muscles. An intra-muscular imbalance is caused by the normal stresses and strains put on muscles during our work and play. These activities only work (train) a fraction of our full range of motion.

More recently, standard data on the strength required by a muscle throughout the various angles of a movement have become available, at least for the lumbar and cervical regions.

Figure 1

Figure 2

Case study

Actual and ideal strength curves at start of therapy (fig. 1): the patient is 49 years old, a medical doctor, water-skier and she suffered chronic back pain radiating down to her legs for years. She completed 18 sessions on the MedX lumbar extension machine and is now free from pain. An interesting feature of this example is the S-shaped strength curve of the first test (figs. 1 and 2). It is indicative of the patient's sport. Water-skiing puts a load on lower back muscles, that is, muscles are trained in the position where the graph shows the patient is strongest. The straight line above is the ideal strength curve (darker grey area on fig. 1). Strength curves at start of therapy (fig. 2, S-shape profile) and at the end (fig. 2, upper light grey profile). Overall strength has improved considerably, the intra-muscular imbalance is largely eliminated and the pain has disappeared.