Talk Science To Me
Referred pain is pain experienced in one site of your body caused by an injury or impairment in a different part of your body. The neurological mechanism of referred pain from is still unknown; however, it is theorized that an afferent abundance of signals from localized myofascial trigger points (MTrPs) may sensitize the receptive field of neurons in the dorsal horn, thus enlarging or expanding the receptive field to include other sites in the same muscle or in other muscles.
Myofascial trigger points (MTrPs) are hyperirritable spots within a taut band of contractured skeletal muscle fibers that produce local and/or referred pain when stimulated, or, simply put, painful muscle knots. Active MTrPs are associated with abnormalities in blood flow (highly resistive vascular bed from compromised capillary circulation due to sarcomere contraction), excessive influx of calcium and sodium into injured tissue from trauma, excessive leakage of acetylcholine in nerve endings possibly inducing spontaneous action potentials, and acidic muscular pH.
Dry needling can elicit referred pain much easier than manual compression, likely due to the higher pressure of needle insertion, which stimulates the sensitive loci and encourages local twitch response (LTR) more frequently. The LTR causes sarcomere lengthening and release of the energy consuming contracture knot that led to tissue ischemia. Following LTRs, an improvement in microcirculation likely occurs that was previously restricted by focal muscle spasm, and thus a reduction in pain.