Tendinopathy
Tendiniopathy is one of the most common sources of acute and chronic pain affecting the general population of all ages as well as the sporting elite.
Tendinopathy is an abnormal structure within a muscle and/or tendon. It is most often caused by muscle overuse.
Tendinopathy is characterised by a build-up of tendon material, mostly collagen, which forms nodules or lumps within the muscle and/or tendon, commonly referred to as "knots".
An in-growth of different types of sensory nerves and the production of a cocktail of "pain" chemicals within the "knots" can produce a wide variety of symptoms including intense sharp shooting, burning and gnawing pain, dull ache, stiffness, weakness, as well as tingling and numbness.
Tendinopathy most often affects the ends of a muscle, where all the forces generated by each muscle cell converges onto your bone. A build-up of collagen can surround a joint, binding it like cement, preventing normal painfree movement.
Because many tendons attach very close to a joint the pain often feels like "joint pain". In fact, studies have shown that tendinopathy often precedes joint derangement such as occurs in osteo-arthritis.
For the technically minded:
Normally, muscle and tendon are highly organised structures. Collagen fibers are more or less aligned along the direction of the muscle with a scattering of tendon building cells, called fibroblasts (cells gaining infamous notoriety). When affected tissues are viewed under a microscope, there is an abundance of hyperactive fibroblasts overproducing highly irregular swirling masses of fragmented collagen fibres.
You'd see splits and gaps where it should be solid. Such tissue is barely equipped to carry out one of its important functions which is to transmit muscle generated forces to your bone. These changes also make the affected tissue more vulnerable to strain, tear or rupture, even during trivial movements.