The Nervous System and Endocrine System: Endorphin Release

Acupuncture needling stimulates the peripheral nerves, resulting in the synthesis and release of endorphins by the central nervous system. The term endorphin was coined by combining the words “endogenous” and “morphine.” Endorphins are a group of opiate-like peptides produced naturally by the body in the spinal cord and brain, where they modulate the transmission of pain signals to reduce the perception of pain by raising the pain threshold. In addition, endorphins work on other body systems, relaxing the cardiovascular system, improving the activity of the immune system, and modifying the endocrine system. All these effects make the patient feel relaxed and speed up the self-healing process.

Acupuncture Needling Normalizes Muscle Physiology

Muscle is the biggest organ in our body and contributes more than 50% of the body weight. It is the most dynamic organ in our body. Please note that here we discuss only the skeletal muscle, not smooth or cardiac muscles. If we do not move our muscles frequently, they become stagnant and lose their ability to function. If we use them improperly, for example, without adequate relaxation between contractions or with excessive repetition, even with sufficient relaxation between contractions, the muscle will become sick and refuse to move any more. This is the built-in self-protection mechanism of muscles.

The sick muscle is painful, spasmodic, tight, swollen, inflamed, fatigued, and starved for energy; it requires more nutrition and an improved oxygen supply to recover. It also requires an increase in blood circulation to remove metabolic toxins, but the tightness of the muscle or the contracture formed in it reduces or blocks the normal blood circulation. This process is a vicious circle of energy crisis in the muscle (see Chapter 3). The sick muscle is no longer responding to the signals from the brain that try to create the necessary relaxation. If this condition persists, acute muscle pain will become chronic and result in atrophy.

When a muscle gets sick, it becomes tight and will resist any further stretching to protect itself from further damage. If the tightness of the muscle continues, some part of the muscle fiber develops a condition of persistent contraction, which is the center of the energy crisis in the muscle. This persistent contraction of muscle fiber is called contracture. When an acupuncture needle is inserted into the tight muscle or into the contracture of the tight muscle, the mechanical movement of the needle breaks the contracting muscle fibers and pushes tight tissue aside.

Other tissue fibers, including the collagen fibers of fascia and other connective tissues, are also broken by the needling. The broken fibers of the connective tissues are entangled at the surface of the fine-diameter needle. There is a physical affinity between the surface of the acupuncture needle and the broken tissue fibers.

The mechanical movement of the needling (pistoning and rotating, see Chapter 3) pulls, moves, and stretches all the broken fibers and leads to mechanical relaxation of the tissues around the needle. Thicker needles like those of syringes do not create this type of physical affinity between the needle surface and the broken fibers.

The mechanical needling of sensory nerve endings also stimulates the corresponding motor neurons to send signals to relax the tight muscles. We described this physiologic process in Chapter 3. Thus the needling immediately produces the effect of relaxation, both mechanically and physiologically. Once the needle is removed, the needle-induced lesion prevents the re-contraction of the broken fibers. The broken tissues, triggered by the lesion, start either reconstruction or replacement of fibers.

As a result, the mechanical and physiologic effect of needling, including the lesion it produces, relaxes the tight muscle and dissolves the contracture. The needle-induced lesion continues the relaxing function for at least 2 days after the treatment, until the lesion is healed.

Acute minor or mild tightness and contraction can be released with one or two acupuncture sessions. If a large area of tightness and contraction is involved such as in chronic muscle pain, repeated treatments are needed.

Once the muscle is relaxed, the blood vessels restore the normal circulation that supplies nutrition and oxygen and removes the metabolic toxins. The restored energy supply resolves the energy crisis and desensitizes the irritated nerve endings. This is how needling and its lesion activate the healing process of damaged muscle.

Immune System: Antiinflammatory Reaction Induced by Acupuncture Needling

Inflammation is a localized protective response elicited by injury or destruction of tissues. Inflammation will destroy, digest, dilute, or wall off both the invaders and the injured tissues. However, the inflammation from injuries often becomes uncontrollable, spreading, swelling, and resulting in heat, pain, and loss of function of the tissues involved. This uncontrollable inflammation will slow down the healing process and may become chronic if not treated early. Acupuncture needling, by creating a very tiny, limited injury and destruction of tissue, triggers a controllable acute inflammation in the body.

Acupuncture needling is perceived as a foreign invader by the body and the needle-induced lesion as an injury or mechanical trauma to the tissues. The needling also causes a tiny amount of bleeding in the soft tissues, which causes hemodynamic changes including dilation of the arterioles and the opening of new capillaries and venular beds in the area. Once the blood vessels become more active, the leukocytes (white blood cells) move from the blood vessels to the injured tissues to engulf and digest invaders and the debris resulting from this destruction. Thus needle-induced inflammation stimulates the inflammatory response, which triggers the healing process.

When acupuncture needles are inserted into the injured and inflamed tissues, each needling site triggers a tiny, local antiinflammatory reaction that speeds up the inflammatory process. This process is a protective strategy of the body, but becomes disabling if it lasts too long and spreads too far. Usually when several needles are inserted into inflamed tissues, swelling, inflammation, and pain will all subside and healing will be accelerated.