What Is That?
A common question therapists are asked is, "what is that?" "Is that a knot?" Hopefully this explaination can help.
Muscle is the largest organ in the human body, and accounts for about 50% of its weight. There are approximately 400 muscles (there are individual variations), and any one of those can develop trigger points which can refer pain and cause dysfunction. Symptoms can range from intolerable agonizing pain caused by "active" trigger points, to painless restriction of movement and distortion of posture from "latent" trigger points.
The answer to "What Are Trigger Points?" is: research it still underway. But many characteristics have been observed for decades by researchers all over the world. With new testing methods and equipment, in the last ten years much has been learned about the physiology of trigger points. And even though not every mechanism is known, patients get better when their trigger points are treated!
Active Trigger Points when pressed feel like "knots" or tight bands in the muscle, and are usually very tender. Healthy muscles usually do not contain knots or tight bands, are not tender to pressure, and when relaxed, they feel soft and pliable to the touch, not hard and dense, even if you work-out. When trigger points are present, on the microscopic level, part of the muscle fiber is contracted into a small thickened area, and the rest of the fiber is stretched thin. Several of these muscle fiber contractures in the same area are probably what we feel as a "knot" in the muscle. These muscle fibers are not available for use because they are already contracted, which is why you cannot condition (strengthen) a muscle that contains trigger points. The sustained contraction probably leads to the release of sensitizing chemicals, producing the pain that is felt when the trigger point is pressed. Eventually some of the structural changes may be irreversible if trigger points are left untreated for long enough. The contractile portions of the fiber in the middle of the knot may separate and retract to each end, leaving an empty portion of the cell in the middle.
Trigger points may refer pain both in the local area and/or to other areas of the body. Common patterns have been well-documented and diagramed. These are called “referral patterns." Approximately 74% of the time trigger points are not located where you feel symptoms, and working on the area you feel a symptom does not give you relief. These referral patterns do not necessarily follow nerve pathways. Pain levels can vary depending on the stress placed on the muscle and any of other the perpetuating factors that keep trigger points activated. Tingling, numbness, or burning sensations are more likely due to nerve entrapments, which may be a result of trigger points entrapping the nerve.
If the trigger point is "active," it will refer pain or other sensations. If it is "latent," it may cause a decreased range-of-motion and weakness. Active trigger points often start with some impact to the muscle, such as an injury, poor posture or body mechanics, repetitive use, or a nerve root irritation. Any of the perpetuating factors can indirectly activate trigger points and make you more prone to developing trigger points that are initiated by impacts to muscles. Active trigger points may at some point cease causing pain, and become latent. Latent trigger points can easily return to being active trigger points, often leading the patient to believe they are experiencing a new problem, when in fact it is an old problem being re-aggravated. Latent trigger points can be reactivated by overuse, over-stretching, or any other of the perpetuating factors.
