Fibromyalgia (FM) is a chronic condition defined by widespread musculoskeletal pain, profound fatigue, and sleep disturbances. While the pain is often diffuse and body-wide, many individuals with FM report intensely tender, localized spots of pain. These painful areas are commonly described as “muscle knots,” raising questions about their relationship to the central pain of fibromyalgia.
Understanding Muscle Knots and Trigger Points
The common term “muscle knot” refers clinically to a Myofascial Trigger Point (TP). A TP is a hyperirritable spot located within a taut band of skeletal muscle or fascia. When compressed, this nodule is painful locally and can also cause pain that radiates, or is referred, to distant, predictable areas of the body.
Myofascial Trigger Points are considered peripheral pain generators, meaning the pain originates at the muscle site itself. They are thought to be caused by acute muscle strain, repetitive microtrauma, or chronic muscle stress. The presence of a palpable, rope-like band and the characteristic referred pain pattern are defining features of an active TP.
Fibromyalgia Pain vs. Myofascial Trigger Points
Fibromyalgia is defined by a central nervous system phenomenon called central sensitization, which amplifies pain signals throughout the body. Historically, the diagnosis of FM relied on the presence of widespread pain and tenderness at specific points, known as Fibromyalgia Tender Points. These tender points were points of generalized tenderness upon pressure, not necessarily palpable knots, and did not produce referred pain like a true TP.
True Myofascial Trigger Points, in contrast, are distinct clinical entities that characterize Myofascial Pain Syndrome (MPS). The key difference is that TPs are localized, palpable knots that cause referred pain, whereas the older Fibromyalgia Tender Points were merely areas of mechanical hyperalgesia, or heightened pain sensitivity, tied to a systemic condition.
However, research now overwhelmingly indicates that a significant percentage of individuals with FM also develop secondary Myofascial Pain Syndrome. This means many FM patients have both the widespread, centrally-driven pain and peripheral, localized TPs that act as independent pain sources.
The coexistence of these two conditions is common and suggests that while FM does not directly cause a TP in the same way a muscle injury does, the systemic changes of FM make the body highly susceptible to their formation. Effectively, the widespread pain of FM is often a combination of central sensitization and the pain generated by multiple, active myofascial trigger points. Clarifying this distinction is important because the treatments for centrally-driven pain differ significantly from the treatments targeting the localized pain of TPs.
The Mechanism of Localized Pain in Fibromyalgia
The link between the centralized pain of FM and the development of peripheral TPs is hypothesized to involve a complex neurophysiological interplay. Central sensitization, the heightened pain processing in the brain and spinal cord, lowers the overall pain threshold for the entire body. This lowered threshold means that minor muscle stressors that a healthy person might tolerate can more easily trigger the sustained muscle contraction that forms a TP in a person with FM.
Once a TP forms, it perpetuates a localized pain cycle that sends further signals back to the already hyper-responsive central nervous system. Scientific analysis of active TPs has revealed elevated levels of various pro-inflammatory substances and specific pain-related neurotransmitters, such as glutamate, at the site of the knot. This localized chemical environment suggests a specific, peripheral pathology is occurring within the muscle tissue of the TP.
Poor microcirculation within the muscle is another contributing factor, as it can lead to a localized energy crisis. The sustained contraction of the taut band restricts blood flow, causing inadequate oxygen supply and a buildup of metabolic waste products. This metabolic stress irritates local pain receptors, which continuously feeds pain signals back into the central nervous system. Addressing these peripheral generators can help reduce the overall burden of pain perceived by the central nervous system.
Targeted Management Strategies for Trigger Points
Successfully managing the localized pain of trigger points requires interventions that specifically target the peripheral knots. Unlike general FM treatments that focus on central pain modulation, these strategies aim to mechanically or chemically disrupt the taut band and the localized pain cycle.
Manual therapies are a common starting point, including specific massage techniques like ischemic compression, which involves applying sustained pressure directly to the TP. Stretching and muscle energy techniques are also employed to lengthen the affected muscle fibers and restore normal range of motion.
For TPs that are resistant to manual techniques, more invasive therapies may be considered for precise, localized relief. Dry needling involves inserting a fine needle into the TP to elicit a local twitch response, which helps to relax the contracted muscle fibers and improve blood flow. Trigger point injections, which use a small amount of local anesthetic, are another option to immediately break the pain-spasm-pain cycle in the knot.