Dry needling involves using a small or fine, sterile needle to penetrate the skin and muscle in the location of the trigger point. The technique is called dry needling because nothing is being injected. A trigger point can be defined as a tight region of the muscle that is tender to palpation. The mechanism of how trigger point dry needling works is not fully understood, however two theories are described. One mechanism involves a local effect to the muscle. A trigger point is like having a knot in the muscle. The knot or trigger point results in decreased blood flow which results in hypoxia or a lack of oxygen and a change in pH. This change in blood flow leads to a change in the chemical properties in the muscle and results in pain. In addition, the trigger point decreases the efficiency of muscle contraction and the ability to properly lengthen or stretch. A second mechanism involves a central effect. When a muscle is dysfunctional, painful or noxious information is being sent between the muscle and spinal cord. Therefore, a loop is formed from the muscle to the spinal cord and back to the muscle. Dry needling is thought to disrupt this feed back loop and reset the muscle. The result of dry needling is a reduction in pain and improved muscle function.
Dry needling is a powerful tool in a treatment plan, however does not always address the primary cause of the dysfunction. A trigger point in the muscle is usually caused by other issues. The cause could be decreased muscle strength or endurance, abnormal joint or soft tissue mobility, or even training errors. A comprehensive treatment plan addressing areas of dysfunction is important to prevent re-occurrence.