A Comparison of the Somatosensory Effects of Therapeutic vs. Medical Massage, Part II

By Gregory T. Lawton, DN, DC

Mechanoreceptors and nociceptors are somatic receptors that act as biological sensors in response to physiological stimuli.The nociceptors respond to abnormal stimuli and transmit this information, most often as pain signals to the higher neurological centers. Mechanoreceptors respond to normal stimuli and transmit this information. Each of these two types of biological sensors tends to dampen or inhibit the other.

Nociceptors are found in the skin and throughout the musculoskeletal system. Nociceptors have been found in almost all connective tissue, with the exception of joint cartilage, synovial membranes, and certain parts of the inner vertebral disc. Nociceptive stimulation due to noxious stimuli has dramatic effects on the nervous system, and has been shown to promote segmental responses such as muscle spasm and increased sympathetic activity. Nociceptor stimulation can also stimulate suprasegmental activity that affects the hypothalamus and can cause sweating, nausea, weakness, pallor and dizziness. A commonly recognized problem in chronic pain is the continuing stimulation of nociceptors.

Mechanoreceptors respond to normal tissue environment and report this homeostatic activity to the central nervous system. Mechanoreceptors appear to respond to weak mechanical signals, gentle movement and pressure, and normal range of motion activities of the joints. Mechanoreceptors do not respond to noxious stimuli and are in fact inhibited by nociceptive input.

The two previous paragraphs, regarding nociceptors and mechanoreceptors are vitally important in understanding what constitutes effective medical massage therapy. Rather than basing our understanding and application of massage therapy technique simply on the theories or pet techniques of a few massage therapists, or upon inaccurate models of physiological function, we should seek to understand the scientific literature that reveals the deeper secrets of physiological function as it pertains to connective tissue therapy.

Based on what is scientifically known about mechanoreceptors and nociceptors, we can suggest the following principles as applied to medical massage therapy:

1. Mechanoreceptors respond to normal connective tissue environment.
2. Nociceptors respond to abnormal connective tissue environment.
3. Mechanoreceptors and nociceptors are widely spread throughout the body tissues, from the skin to the periosteum.
4. Almost all connective tissues contain mechanoreceptors and nociceptors.
5. Mechanoreceptor stimulation will dampen or inhibit nociceptor stimulation.
6. Nonciceptor stimulation will dampen or inhibit mechanoreceptor stimulation.
7. Almost all conditions treated by the medical massage therapist involve nonciceptive symptoms.
8. Almost all conditions treated by the medical massage therapist can be improved through mechanoreceptor stimulation.

The above eight principles provide the medical massage therapist with both a mandate and an outline for delivering medical massage therapy. In addition, the medical massage therapist can use the scientific evidence from studies on mechanoreceptors and nociceptors to judge and evaluate massage therapy technique. Clearly, the scientific literature supports manual therapy technique that promotes responses in mechanoreceptors and any technique or activity that dampens or inhibits nociceptors. Four aspects of clinically effective treatment can be identified from the eight principles outlined above:

1. Massage therapy technique should stimulate mechanoreceptors through gentle pressure and joint movement.
2. Massage therapy technique should be directed at all connective tissue structures known to harbor mechanoreceptors, from superficial to deep structures, but this technique must stimulate mechanoreceptors, not nociceptors.
3. Massage therapy technique should include gentle joint mobilization technique designed to stimulate mechanoreceptors in all connective tissues and the joint complex.
4. Positive connective tissue clinical results will continue long after the massage therapy treatment due to the "normalization" of connective tissue and joint complex activities that will increase mechanoreceptor activation and will inhibit nociceptor stimulation.

Therapeutic massage techniques (or any system of massage therapy) that stimulates nociceptor activity via painful and improper technique, will retard and delay the healing of injured connective tissues. Specifically, techniques that are improperly applied such as trigger point therapy and periosteal or deep tissue techniques will stimulate nonciceptive input, muscle spasm, pain, sympathetic hyperactivity, and supra-segmental physiological responses.

It should now be clear that the proper application of medical massage technique should include the avoidance of technique that stimulates nociceptive responses in the nervous system. This stimulation has a negative effect on the outcome of the treatment and the patient's healing process. From this viewpoint, pain is not gain. The massage therapist who wishes to apply the principles presented here in the clinical application of massage therapy technique probably needs to make subtle changes in manual technique. These changes include the following:

1. Deep tissue techniques should be applied with a "soft hand technique."
2. Deep tissue techniques should be applied first with a gentle pressure into the tissue for a depth of one to three centimeters (to stimulate the mechanoreceptors), then to the depth of the periosteum or joint complex.
3. Joint mobilization techniques should be applied first with supportive manual pressure on the joint, then with gentle normal range of motion.
4. All approachable connective tissue at the joint complex should be systematically massaged, then mobilized.

Medical massage therapy is a scientifically based method of manual therapy. Medical massage seeks a clear understanding of the scientific principles of physiology that affect connective tissue healing and treatment. Many currently utilized therapeutic massage techniques unnecessarily inflict patient pain and exacerbate the patient's condition, due to a faulty and erroneous viewpoint regarding biological sensory input and "proproceptors." This material is offered to all massage therapists, to clarify this issue and to offer more effective treatment methods. The next time you see an article showing (r a massage instructor demonstrating) trigger point therapy with the elbow buried an inch into the levator scapula and trapezius, consider the nociceptive stimulation this technique is provoking and reconsider the value of this type of technique.

Regardless of what we call or label the manual therapy techniques that we apply to clinical cases, we must, as massage professionals, recognize the need to thoroughly investigate current scientific research regarding connective tissue pathophysiology and reconsider our technique and treatment protocol based on this knowledge. For those massage therapists who prefer to practice general relaxation massage in recreational settings, while they may voluntarily choose not to practice medical massage, they must also recognize and understand the higher mechanisms of connective tissue rehabilitation and the ability of the medical massage therapist to treat connective tissue pathology.

The pet techniques of the massage therapist should not determine the patient's treatment. Treatment should be based on the findings, diagnosis, causation and symptoms of the patient's presenting problem or condition.

The allied medical professions and the chiropractic profession can also benefit from a detailed education in medical massage technique and protocol. The application of non-exacerbating technique directed at the primary area of pathology in most musculoskeletal disorders, the joint complex, is of profound value to medical massage therapists, chiropractors, physical therapists, occupational therapists, nurses and physicians who treat connective tissue disorders. Medical massage therapy may effectively become the pivot point where many of these health care practitioners come together in a common understanding of massage therapy.

References and suggested reading:

1. Sensory Integration, Theory and Practice, Fisher, Murray, and Bundy, F.A. Davis Company, 1991.
2. Proprioceptor: An Obsolete, Inaccurate Word, Journal of Manipulative and Physiological Therapeutics, Volume 20, Number 4, May 1997.
3. Medical Massage and the Pathophysiology of Connective Tissues, G. Lawton, American Medical Massage Association, 2000.
4. Tendon and Ligament Healing, A New Approach Through Manual Therapy, W. Weintraub, North Atlantic Books, 1999.