Terminology
Active Myofascial Trigger Point: An area within a muscle that is hyper-irritable and is causing a pattern of referred pain at rest or in motion that is specific for that muscle. An active trigger point is tender, prevents full lengthening of the muscle, weakens the muscle, usually refers pain on direct compression, mediates a local twitch response of its taut muscle fibers when adequately stimulated, causes tenderness in the pain reference zone, and often produces specific referred autonomic phenomena. To be distinguished from a latent trigger point.
Acute: Of recent onset (hours, days, or a few weeks).
Chronic: Long-standing (usually longer than six months), but not necessarily irreversible. Symptoms may be mild or severe.
Latent Myofascial Trigger Point: An area within a muscle or its fascia that is painful only when compressed. A latent trigger point may also restrict range of motion and weaken the muscle, but does not refer pain.
Myofascial Trigger Point (Clinical Definition): A hyper-irritable spot in skeletal muscle that is associated with a hypersensitive palpable nodule in a taut band. The spot is painful on compression and can give rise to characteristic referred pain, referred tenderness, motor dysfunction, and autonomic phenomena.
Referred (Trigger-Point) Pain: Pain that arises in a trigger point, but is felt at a distance, often entirely remote from its source. The pattern of referred pain is reproducibly related to its site of origin.
Spasm: Increased tension with or without shortening of a muscle due to non-voluntary motor unit action potentials. Spasm cannot be stopped by voluntary relaxation. Spasm should be distinguished from contracture. Tightness of a muscle may or may not be caused by spasm.
Trigger Point Pressure Release: Application of progressively stronger, painful pressure on a trigger point for the purpose of eliminating the trigger point's tenderness and hyper-irritability