A Trigger Point (TP), also known as a myofascial trigger point, is a localized, sensitive area within a muscle or fascia (the connective tissue surrounding muscles) that can be painful when pressed or otherwise stimulated.
From the histopathological point of view, TP is characterized by the presence of muscle knots, which corresponds to a muscle fiber segment subjected to a strong contraction of its sarcomeres.
Shrinkage knots are microscopic formations that correspond to sites of spontaneous electrical activity in the neuromuscular junction, which is a specialized synapse of the motor neuron that innervates the muscle fiber.
The area or region of muscle fibers that contain knots of contraction constitutes the palpable painful muscle nodule.
Only some fibers of the affected muscle present this microscopic alteration. At the level of contraction nodes, sarcomeres present a strong contraction (shorter and wider) differing markedly from the sarcomeres of the normal muscle fibers of the same muscle.
The existence of muscle knots in an area affects the function of the entire muscle.
Trigger Points do not cause pain during normal activities. They are only painful with palpation.
They are activated by cold, heat, pressure changes
atmospheric, and repetitive damage.
The reason why a TP is formed in a certain moment and in a certain muscle is still unknown despite the many hypotheses issued.
However, multiple pathogenic factors have been found to trigger, predispose, or favor TPs which are fundamentally:
- Muscular stress: caused by excessive physical exercise of the muscles involved.
- Repetitive microtrauma.
- Acute musculoskeletal trauma: it can affect muscles, tendons, ligaments, or bursae (e.g. “whiplash cervical”).
- Accumulation of metabolic waste products in muscle tissues.
- Sudden cooling of the body or partial body areas: (Staying in front of a fan or air conditioning).
- Exhaustion or generalized fatigue: For example in the Chronic Fatigue Syndrome.
- Joint inflammations.
- Nerve injury.
- Poor Posture: Maintaining poor posture over time can create imbalances in muscle tension, leading to the development of TPs.
- Stress and Tension: Stress and emotional factors can contribute to muscle tension, leading to the formation of TPs.
Clinically, the patient manifests dull and heavy pain, the muscle feels tense, hypertonic, and contracted.
The muscle is exhausted quickly and significantly decreases sports performance.
Treatment for trigger points may include physical therapy, sports massage therapy, myofascial release techniques, stretching exercises, and sometimes the use of heat therapy.