Body Mechanics: Muscle Imbalances

Welcome back to Body Mechanics. I wanted to wish every one a happy and prosperous New Year. I hope everyone turns over a new leaf and finds the strength and conviction to adhere to their resolutions. I also wanted to personally thank Matt for updating the site to reflect his vision and to make the site easier to navigate for you, the reader. He has been working long hours and the new look site is a direct reflection of his work ethic and passion. We thank you kindly for your dedication and work Matt.

Let’s get started! In our previous discussion we covered the planes of movement. I touched base on their importance in preventing muscular imbalances that could potentially lead to injury. Today we will continue to further develop this topic and in the following weeks we will elaborate on other aspects associated with postural and muscular imbalances. One imbalance that you may unknowingly be aware of that can help us understand this concept is the difference in strength between your left and right hand. Depending on whether you are lefty or a righty, you will exhibit more strength in your dominant hand. Even if you are ambidextrous there will always be one side slightly dominant because of our tendency to repeatedly use either/or.

The biggest concern however, is how it affects our posture, which inhibits our length-tension relationship, as well as our force-velocity curve. This typically happens anteriorly and posteriorly (not exclusively) and can be seen with the rounding of the shoulders. Imagine if you will, two teams playing tug of war with a pit in the middle. The stronger team on the right over time will continue to pull the opposing team until they fall into the pit. Hypothetically, that is what is happening every time our body is forced into a repetitive posture or movement. Our muscles over time will compensate and strengthen the body in an unbalanced state. In the case above, it would be the pectoral muscles and those that assist in movement in which the pectorals functions that become stronger and shortened. While the muscles of the back become lengthened and weak.

There may be a lot of factors leading to this type of postural and muscular imbalance. One such factor is through work. Imagine sitting at a desk everyday for eight hours a day, five days a week, 20 days a month for a total of 240 days a year. That is more than half a year. Most of you that frequent know that repeatedly performing a movement will lead to an adaptation. The problem in this case is a negative adaptation and one that must be addressed immediately.

Since our body is creating an adaptation to what we repeatedly do, the length tension relationship becomes altered. “Length-tension relationship refers to the length at which a muscle can produce the greatest force. There is an optimal length at which the myosin and actin filaments in the sarcomere have the greatest degree of overlap” NASM essential of strength and conditioning Michael A. Clark.

In other words, as our joints move out of the sweet spot, our muscles become shortened and lengthened at opposing muscles. I’m sure you’ve heard the term for every action there is an equal and opposite reaction. The body works in the same way, as our muscles cannot undo the movement it has completed. The body functions with agonist and antagonist muscle contractions. This means that when the arm is flexed at the elbow, the biceps are being contracted. To extend the arm back to the original position the triceps must now reverse the movement, not the biceps muscle by eccentrically contracting. If this relationship is negatively altered, it forces one to become stronger and the other to become weaker. Even though one becomes stronger it will adversely affect the force-velocity curve because the concentric contraction has a reduced range of motion that is not optimal. When this happens our maximal effort of strength exerted is not actually our best, but rather a reduced percentage of our actual potential.

It is imperative that when we train, we are considering our weakness, for in our weaknesses we will find our greatest gains.

Happy Lifting!

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