Trigger points, also known as myofascial trigger points, are localized areas of tenderness or sensitivity in the muscles, fascia, and surrounding tissues. These points can cause pain, discomfort, and limited range of motion in the affected area and can also refer pain to other areas of the body.
Trigger points are usually caused by muscle overuse, injury, or stress and can develop in any muscle or muscle group in the body. They are often associated with muscle knots or tight bands of muscle fibers that can be felt under the skin.
How these trigger points forms involves a complex interaction between muscular, neurological, and biochemical factors.
Initially, there may be some form of muscle injury or overuse, which causes microtrauma to muscle fibers and surrounding connective tissue, leading to the formation of a trigger point. This trauma leads to the release of inflammatory mediators, such as histamine and cytokines, which contribute to local inflammation and sensitization of nociceptors, the sensory nerve endings that transmit pain signals.
As the trigger point develops, it becomes a self-sustaining cycle of pain and dysfunction. The muscle fibers become shortened and tense, and the fascia surrounding the muscle becomes thickened and less pliable. This results in decreased blood flow and oxygenation to the area, further exacerbating the pain and dysfunction.
Additionally, trigger points can cause neurological changes, such as sensitization of the central nervous system, which can lead to the perception of pain even in the absence of ongoing tissue damage. Trigger points can also cause referred pain, where pain is felt in a different part of the body than where the trigger point is located, due to shared nerve pathways.
Think of a trigger point as a traffic jam on a busy highway. The traffic jam represents a muscle injury or overuse, which causes a buildup of tension and congestion in the affected area. The cars represent the muscle fibers, which become shortened and tense due to the buildup of tension.
As the traffic jam persists, it causes a ripple effect, with congestion spreading to other parts of the highway. This is similar to how trigger points can cause referred pain, where pain is felt in a different part of the body than where the trigger point is located, due to shared nerve pathways.
Furthermore, the congestion in the traffic jam causes a lack of oxygen and nutrients to the affected area, similar to how trigger points can result in decreased blood flow and oxygenation to the area, further exacerbating the pain and dysfunction.
Trigger points are often the cause of musculoskeletal pain and why massage balls and foam rollers have become so popular.