In the last blog we discussed how nociception, your body’s stress signal, can increase muscle tone completely independent of any conscious pain experience. The next reason for increased muscle tone is joint instability. For instance, if the ligaments surrounding a joint aren’t doing their job well enough, due to injury or general laxity, then the muscles around that joint are going to tighten up to keep that area stable. A far more common reason for instability, though, is muscular inhibition. If the primary stabilizing muscles around a joint aren’t doing their job, then secondary stabilizing muscles are going to increase in tension to make up for their inhibited counter-parts.
A very common example of this is in the low back. The primary stabilizing muscles of your low back are your abdominal respiratory muscles; your diaphragm, pelvic floor, multifidi and abdominal muscles. All of these muscles act as a unit; if one of them is firing insufficiently then all of them will. Anytime proper abdominal breathing is disrupted (self image neuroses, surgeries, metabolic acidosis etc.) then your low back becomes de-stabilized, causing all the surrounding muscles to increase in tone to hold you together.
Anytime muscle tension increases in a standing position and decreases while lying down, the purpose for that tension is stabilization. If all muscles are firing and joints are properly aligned and stabilized then extremely little tension has to exist to maintain an upright posture. It’s very common for clients to complain of limited ROM in a joint, but when placed in a seated or lying position, they then have full ROM. The reason for the limited mobility while standing is instability somewhere. And instability in a low back can absolutely result in a loss of mobility in a shoulder or neck. Proximal stability is necessary for distal mobility.