Occasionally, a specific muscle may generate pain due to sustained contraction and subsequent localized ischemia & oxygen deprivation. While this type of pain is usually secondary to another problem, it can occur primarily. These areas of muscle pain (as seen above) are called trigger points and are described as irritable spots in skeletal muscle that are associated with palpable taut & tender bands of muscle fibers.
Researchers believe that these tense are small contraction knots and a common cause of pain. Compression of a trigger point may elicit local tenderness, referred pain, or local twitch response. It also creates an increased local energy demand. This local energy crisis releases neuroreactive biochemicals which sensitize nearby nerves. The sensitized nerves initiate the motor, sensory, and autonomic effects of myofascial trigger points by acting on the central nervous system. Muscles with trigger points are muscles in a constant state of energy crisis.
The trigger point model states that unexplained pain frequently radiates from these points of local tenderness to broader areas, sometimes distant from the trigger point itself. Practitioners claim to have identified reliable referred pain patterns, allowing practitioners to associate pain in one location with trigger points elsewhere.