Trigger Points: Trigger points are discrete, focal, hyperirritable spots located in a taut band of skeletal muscle. They are usually found as sore or tender round spots in muscles. You can usually “move” them around. Many of them are found near muscle/tendon junctions or near tendon/bone junctions. They can produce pain locally and/or in a referred pattern and often accompany chronic musculoskeletal disorders. Acute trauma or repetitive micro trauma may lead to the development of stress on muscle fibers and the formation of trigger points. Tender Points are like trigger points, but do not refer or radiate pain out.
Tender points/trigger points can be painful for several reasons. First there is inflammation or swelling around the knot, which is painful in itself. Secondly, as the muscle is in continual contraction it fatigues (painful) and waste products (lactic acid – painful) build up. Thirdly it can build neural “links” to other nerves stimulating their pain fibers. Very similar to sclerodermal pain from a heart attack is referred to your left shoulder. Fourthly, the rest of the muscle is now not working at its optimum level or ergonomics because a portion of it isn’t working in concert with the rest of the fibers. This can overburden the rest of the fibers and not make them as effective.