Myofascial trigger points, also known as trigger points, are described as hyperirritable spots in the fascia surrounding skeletal muscle. They are associated with palpable nodules in taut bands of muscle fibers. They are a topic of ongoing controversy, as there is limited data to inform a scientific understanding of the phenomenon. Accordingly, a formal acceptance of myofascial "knots" as an identifiable source of pain is more common among bodyworkers, physical therapists, and chiropractors and osteopathic practitioners. Nonetheless, the concept of trigger points provides a framework which may be used to help address certain musculoskeletal pain.
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 which associate pain in one location with trigger points elsewhere. There is variation in the methodology for diagnosis of trigger points and a dearth of theory to explain how they arise and why they produce specific patterns of referred pain. Compression of a trigger point may elicit local tenderness, referred pain, or local twitch response. The local twitch response is not the same as a muscle spasm. This is because a muscle spasm refers to the entire muscle contracting whereas the local twitch response also refers to the entire muscle but only involves a small twitch, no contraction.
Therapists may use myotherapy (deep pressure, massage or tapotement), mechanical vibration, pulsed ultrasound, electrostimulation, ischemic compression, and stretching techniques that invoke reciprocal inhibition within the musculoskeletal system. Practitioners use elbows, feet or various tools to direct pressure directly upon the trigger point, to avoid overuse of their hands.
A successful treatment protocol relies on identifying trigger points, resolving them and, if all trigger points have been deactivated, elongating the structures affected along their natural range of motion and length. In the case of muscles, which is where most treatment occurs, this involves stretching the muscle using combinations of passive, active, active isolated (AIS), muscle energy techniques (MET), and proprioceptive neuromuscular facilitation (PNF) stretching to be effective. Fascia surrounding muscles should also be treated to elongate and resolve strain patterns, otherwise muscles will simply be returned to positions where trigger points are likely to re-develop.
The results of manual therapy are related to the skill level of the therapist. If trigger points are pressed too short a time, they may activate or remain active; if pressed too long or hard, they may be irritated or the muscle may be bruised, resulting in pain in the area treated. This bruising may last for a 1–3 days after treatment, and may feel like, but is not similar to, delayed onset muscle soreness (DOMS), the pain felt days after overexerting muscles. Pain is also common after a massage if the practitioner uses pressure on unnoticed latent or active trigger points, or is not skilled in myofascial trigger point therapy.