What Is Tension?
Have you ever stretched a muscle for days on end with little impact on the perceived tightness of that tissue? Maybe you tried foam rolling it, performed banded distraction work, or dug into it with a massage tool, but the tissue is as stiff as ever. If you are not seeing changes in mobility with the work you’re doing you need to take a step back, reassess, and view the body as a system of systems. If you aimlessly stretch, smash, and roll tissues it is unlikely that you’ll find the long term developmental progress that you’re seeking.
Muscle tension, and subsequently mobility, is highly regulated by the central nervous system. Despite the negative connotation that the word tension carries in the high performance community it is not something to be feared. Humans live and die by tension. Without sufficient muscle tension we lack the ability to create intramuscular compression and regulate our blood pressure during activity. Additionally, tension is needed to tolerate any meaningful external load placed on us. Our bodies are held together by a network of length tension relationships and without these relationships we would lose the ability to generate movement, let alone keep ourselves upright. Tension simply refers to the degree of tautness in the muscles at any given point. Our muscles are never entirely relaxed, even where we are at rest. The amount of muscle tension our tissues maintain at rest can be altered and it plays a role in determining our active and passive ranges of motion, both of which are relevant for performance. If resting muscle tension is too low then muscles cannot contract as rapidly or produce as much work. On the other hand, if tension is too high then muscles are less efficient at contracting and producing force, and their active range of motion may be impaired as well.
Our bodies maintain our muscle tension based on both active and passive components and the nervous system actively adjusted tension based on feedback it receives from the muscle itself. Specific portions of the muscle such as the muscle spindle cells monitor the degree of stretch in the muscle and relay that information back to the central nervous system. If the muscle is stretched too much, or too little, the brain responds by altering the length of the tissue and resetting it’s tension. Additionally, muscle tension can be manipulated through physical training and movement based therapies. This can be a natural, unintended, outcome of our training or it can be something that is strategically altered as a means of optimizing force production and efficiency.
Stretch Physiology
The stretch reflex is set by the central nervous system based on our previous experiences and our muscles capability of functioning within a given range. If we spend much of our time in a certain position, or posture, our body will adapt in order to maximize efficiency within those active ranges. In order to change our default setting, so to speak, we need to disrupt the system. The central nervous system is resistant to significant changes, and it will guard against disruptions and perturbations. If you try to take a joint past it’s normal active range your body will react by pulling you back into your normal range. This process is mediated through the stretch reflex. If we want to increase an athlete's active range of motion we first need to improve their ability to control themselves in all of their currently accessible ranges, then we can begin teaching their nervous system to control progressively larger ranges as well as preparing tissues to function in these newly acquired ranges. The simplest way to accomplish this is through a combination of stretching and isometric loading. For example, taking a given joint to, or near, it’s end range of motion and then applying an isometric muscle control above eighty percent of the maximum voluntary contraction force. This will override the stretch reflex and allow one to gain access to newly acquired ranges or motion. Isometrics are the safest and most effective way to bypass the stretch reflex and are highly effective for activation motor units. Additionally, this process can be expedited through the use of breathing drills that help to change mobility and move athletes into new ranges of motion in a safe manner. Mind you, athletes will not maintain all of their newly acquired ranges of motion, but they will retain some of it. In this way the process of increasing active range of motion is akin to taking three steps forward and two steps backward. It's a continuous battle to gain new ranges and capture them through deliberate movement practices, breathing patterns, and habits.
Identifying tension
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