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Muscle Tension, Muscles, and Movement: T-Shirt Analogy

We understand that muscles contract, but in order to understand how muscle tension develops in the body, we need to take a closer look at the physiological mechanics and sequence of events required to create muscle movement.

Our muscles are a collection of thousands of muscle fibers that run the length of the muscle. These fibers are different from a string or thread that is {solid and with no spaces within it} {from end to end} but instead are made up of thousands of sarcomeres that each function to shorten a certain distance.

For illustrative purposes, imagine that each sarcomere is a link in a chain (i.e., the muscle fiber) and the distance it can shorten is the space within each of the links. In order for a muscle fiber to shorten (i.e., contract), all of its sarcomeres – the chain links – shorten at the same time. And the collective shortening of sarcomeres and muscle fibers within a muscle creates a muscle contraction.

We can now apply our new understanding of muscle physiology and mechanics to examine the relationship between muscle tension and {“permanent”} {progressive} shortening of muscles.

Imagine that you are at the gym doing bicep curls with a dumbbell. Each repetition requires the recruitment of muscle fibers which means that every time you lift the weight, tens of thousands of sarcomeres are shortening . And in a perfect world, each time you release the muscle to bring the weight back down, all of the sarcomeres – chain links – would release as well. Unfortunately, this is not the case, and when sarcomeres bind together (instead of releasing) the muscle effectively shortens and tension is generated. Due to the tremendous number of sarcomeres within the body, it’s impossible to notice when a few get “stuck.” But when we repetitively train these muscles such that more and more sarcomeres get “stuck”, we exacerbate the problem, and tension breeds more tension until ultimately we develop a mass of tissue known as a knot.

T-Shirt Analogy: Understanding Muscle Tension and Knots

To illustrate the effect of knots within muscles, we will use the example of a t-shirt being twisted. When the shirt is only slightly twisted, there is little effect on the surrounding areas and there remains a fair amount of pliability within the surrounding fabric. However, as the shirt continues to get twisted (knotted), more of the surrounding fabric gets pulled into the center until even the distant ends of the shirt are affected. This analogy illustrates how knots (i.e., non-functional sarcomeres) effectively shorten muscles and limit their ability to maximally contract through full ranges of motion.

Biomechanical Misalignment: Chain Link Analogy


Nic Bartolotta

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Nic Bartolotta

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