The Limitation of a Biomechanical Model of Massage Therapy
/The Canadian Medical Association recently revised a number of their Clinical Practice Guidelines. Notably, the updated 2017 Canadian Guideline for Opioids for Chronic Non-Cancer Pain (Busse et al. 2017) now recommends a trial of massage therapy rather than a trial of opioids for a number of conditions, including: back pain, knee osteoarthritis, neck pain, and headaches. Based on these new practice guidelines Registered Massage Therapists will see an increase in direct physician referrals as front line treatments for acute and chronic pain.
As the body of evidence to support the use of massage therapy continues to grow, articulating the science behind what we do will help build rapport and facilitate incoming physician referrals. This post is an excellent opportunity to look into the therapeutic mechanisms of massage.
The Human Body is Complex and Adaptable
“Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.” - The International Association for the Study of Pain (IASP)”
Increasingly, research shows that attributing the experience of pain solely to poor posture, minor leg length discrepancies, vertebral misalignment and other structural abnormalities is an oversimplification of a complex process. Even in the case of degenerative changes, several landmark studies have shown that tissue tears revealed on imaging are a part of normal aging. This disconnect between tissue damage seen on imaging and clinical presentation often creates confusion for both patients and clinicians. As a result the medical community has moved on from a traditional biomechanical model into a biopsychosocial model (Lewis et al., 2020; Lin et al., 2020).
Humans are complex and are comprised of many overlapping systems, knowing how they interact is important for any therapist. The general consensus is that structural abnormalities alone do not explain or necessarily predict pain. The reason people experience pain differently is in part is due to differences in genetics, depression, emotional stress, history of physical trauma and sensitization of the nervous system. In contrast to a biomechanical model a biopsychosocial model puts into perspective the interaction of biological factors (genetic, biochemical, etc.), psychological factors (mood, personality, behavior, etc.), and social factors (cultural, socioeconomic, etc.). Central to this framework there are a couple of overlapping therapeutic mechanisms of action that we will explore in this article.
Affective Touch - Therapeutic massage is a source of safety, comfort and relief
Socially appropriate interpersonal touch has been shown to stimulate the release of neurochemicals (endogenous opioids and oxytocin) associated with relaxation and pain relief (Vigotsky et al., 2015; Walker et al., 2017). Massage therapy has been shown to have an effect on cortisol levels, but the effect is generally small and, in most cases not clinically significant. In general a reassuring therapeutic encounter, in which a patient is provided with compassionate touch, provides the patient with a safety message. This can result in reduced physiological and behavioural reactivity to stressors and improved mood/affect.
Just as noxious stimulation is detected by nociceptors; Pleasant stimulation is detected by specialized C-tactile fibers. Therapeutic massage stimulates C-tactile fibers, this input provides the body with a safety message. This message can help mitigate the transition, amplification and development of chronic pain - for more on safety messages I recommend the book - Explain Pain Supercharged by Lorimer Moseley and David Butler.
“We will experience pain when our credible evidence of danger related to our body is greater than our credible evidence of safety related to our body. Equally we won’t have pain when our credible evidence of safety is greater than our credible evidence of danger”- Lorimer Moseley
Neurological Factors - Therapeutic massage stimulates specialized sensory nerves
What stuck with me after reading The Brain That Changes Itself is the idea that the neuroimmune system is constantly adapting to external stimulus. This inherent plasticity provides us with an opportunity to utilize non-noxious therapeutic inputs as a first line of defense against pain. Therapeutic massage is processed by specialized sensory receptors located in cutaneous and subcutaneous structures. These specialized mechanoreceptors are what informs the body about the type of input they are receiving, there are five major types of mechanoreceptors that massage therapists should be aware of:
• Two of these are located in the superficial layers of the skin: Merkel cells and Meissner corpuscles.
• Two receptors, the Pacinian corpuscle and the Ruffini corpuscles, are found in the subcutaneous and deeper tissue layers.
• The fifth major type of mechanoreceptor are newly discovered C-tactile fibers that play a specific role in transmitting the pleasurable properties of touch.
Pain is a complex experiential phenomenon that is processed and relayed at various levels in the nervous system. Low intensity, non-noxious, stimulation of cutaneous sensory nerves prevent the spinal cord and brain from amplifying nociceptive signaling. This gating of the ascending nociceptive input, helps modulate the experience of pain.
Furthermore, research collaborators from Université du Québec à Trois-Rivières and Texas Tech have shown that passive mobilization may be particular helpful in combating nerve inflammation. These researchers showed that in cases of peripheral nerve irritation five minutes of passive mobilization (incorporating stretch/relax cycles) may help to diminish intraneural edema and/or pressure (Boudier-Revéret et al., 2017). This will have a modulatory effect on peripheral and central processes.
The brain is a far more open system than we ever imagined, and nature has gone very far to help us perceive and take in the world around us. It has given us a brain that survives in a changing world by changing itself. - Norman Doidge: The Brain That Changes Itself
Contextual Factors - A person-centered clinical experience enhances the natural healing capacity of the body
It has long been known that the way a clinician presents both themselves and their treatment, is tied to health-related outcomes – this is known as the contextual factors of a therapeutic encounter (Rossettini et al., 2018). In the book How Healing Works: Get well and stay well using your hidden power to heal, Wayne Jonas talks about creating an optimal healing environment. This involves providing a person-centered clinical experience that embraces the placebo response and the natural healing capacity of the body.
In essence, behaviours and interactions with patients facilitate a relaxation response that will help to influence health-related outcomes; the magnitude of a response is influenced by mood, expectation, and conditioning.
“By definition, CFs (Contexual Factors) are physical, psychological and social elements that characterize the therapeutic encounter with the patient. CFs are actively interpreted by the patient and are capable of eliciting expectations, memories and emotions that in turn can influence the health-related outcome, producing placebo or nocebo effects.” – Rossettini et al., 2018
Mechanical Factors - Therapeutic massage influences tissue and cell physiology
Growing up I was involved with hockey, soccer and distance running, so I had my fair share of injuries. Most of these were minor muscle strains, but a couple of the more severe injuries required casting and a significant amount of time away from my sport. As a result of these prior experiences, I developed an interested in the role of early rehabilitation for injuries. Along with contextual and neurological responses a number of researchers have investigate the effect of manual manipulation on cellular signaling and tissue remodeling.
A study from Geoffrey Bove published in The Journal of Neurological Sciences looked at the effect of modeled massage on transforming growth factor beta (TGF-β1) induced fibroblast to myofibroblast transformation. This is potentially impactful in postoperative rehabilitation because TGF-β1 plays a key role in tissue remodeling and fibrosis (Bove et al., 2016). This was recently followed up by a study published in the prestigious journal Pain showing that by attenuating the inflammatory response (with modelled massage) in the early stages of an injury, they were able to prevent the development of neural fibrosis (Bove et al., 2019).
Along the same lines a joint research project between Timothy Butterfield of The University of Kentucky and researchers at Colorado State University demonstrated that modeled massage enhanced satellite cell numbers (Miller et al., 2018). Similarly earlier research from Butterfield and his collaborators at the University of Kentucky proposes that mechanical stimulation prompts a phenotype change of M1 macrophages into anti-inflammatory M2 macrophages. Taken together the increase in satellite cell numbers and reduction in inflammatory signaling may improve the body's ability to respond to subsequent rehabilitation (Waters-Banker et al., 2014).
One Size Does Not Fit All
Over time the supportive theories behind techniques evolve or change completely. It is becoming increasing evident that a biomechanical model as a basis for treatment is outdated based on the latest research into pain science. As we have seen in numerous examples in the literature structural biomechanical factors alone do not explain or necessarily predict pain. The shift from a biomechanical model to a biopsychosocial model helps put into context the interconnected and multi-directional interaction between: physiology, thoughts, emotions and beliefs. Based on this framework investigation into mechanisms for symptoms should extend beyond local tissue changes and include peripheral and central mechanisms of nociception modulation.
What this means to practicing therapists is that there are multiple levels at which pain may be alleviated by therapeutic measures. Through a process of gently stretching muscles, neurovascular structures and investing fascia nociceptive processing associated with tissue damage (actual or perceived) is modifiable in such a way that the pain subsides. Preferential sites for stimulation are associated with areas rich in specialized sensory receptors such as Merkel cells, Meissner corpuscles (superficial layers of the skin), Pacinian and Ruffini’s corpuscles (joint capsules & subcutaneous tissue) and C-tactile fibers which play a role in the signaling of affective aspects of human touch.
Massage Therapy: A Biopsychosocial Framework
The next five years will be an exciting time for the profession, it is a time to ‘bridge the gap’ with the medical profession and provide easier access to massage therapy. Additionally, the paradigm shift from a biomechanical model to a biopsychosocial model presents us with an opportunity to reevaluate how we communicate with other healthcare professionals. A biopsychosocial model is one that seeks to understand the complex web of interactions in the patient’s history, physiology and lifestyle. In terms of clinical responses to massage therapy there are a number of overlapping mechanism in the periphery, spinal cord, and brain, including but not limited to:
Affective Touch - Interpersonal touch mediates the release of neurochemicals. Which can result in reduce physiological and behavioral reactivity to stressors and improved mood/affect.
Contexual Factors - A positive therapeutic encounter is tied to clinical outcomes; the magnitude of a response is influenced by mood, expectation, and conditioning.
Neurological Factors - Therapeutic stimulation of somatosensory nerves inhibits nociceptive processing and activate descending inhibitory mechanisms. This influences neuro-immune processes correlated with the experience of pain.
Mechanical Factors - Gentle stretching of neurovascular structures and muscles induces a molecular response that helps diminish intraneural edema and expedite clearance of noxious biochemical by-products (cytokines, prostaglandins, and creatine kinase).
More to Explore
Bialosky, J. E., Beneciuk, J. M., Bishop, M. D., Coronado, R. A., Penza, C. W., Simon, C. B., & George, S. Z. (2018). Unraveling the Mechanisms of Manual Therapy: Modeling an Approach. The Journal of orthopaedic and sports physical therapy, 48(1), 8–18. doi:10.2519/jospt.2018.7476
Boudier-Revéret, M., Gilbert, K. K., Allégue, D. R., Moussadyk, M., Brismée, J. M., Sizer, P. S., Jr, Feipel, V., Dugailly, P. M., & Sobczak, S. (2017). Effect of neurodynamic mobilization on fluid dispersion in median nerve at the level of the carpal tunnel: A cadaveric study. Musculoskeletal science & practice, 31, 45–51. https://doi.org/10.1016/j.msksp.2017.07.004
Bove, G. M., Harris, M. Y., Zhao, H., & Barbe, M. F. (2016). Manual therapy as an effective treatment for fibrosis in a rat model of upper extremity overuse injury. Journal of the neurological sciences, 361, 168–180. doi:10.1016/j.jns.2015.12.029
Bove, G. M., Delany, S. P., Hobson, L., Cruz, G. E., Harris, M. Y., Amin, M., … Barbe, M. F. (2019). Manual therapy prevents onset of nociceptor activity, sensorimotor dysfunction, and neural fibrosis induced by a volitional repetitive task. Pain, 160(3), 632–644. doi:10.1097/j.pain.0000000000001443
Busse, J. W., Craigie, S., Juurlink, D. N., ... Guyatt, G. H. (2017). Guideline for opioid therapy and chronic noncancer pain. CMAJ : Canadian Medical Association journal, 189(18), E659–E666. https://doi.org/10.1503/cmaj.170363
Geri, T., Viceconti, A., Minacci, M., Testa, M., & Rossettini, G. (2019). Manual therapy: Exploiting the role of human touch. Musculoskeletal science & practice, 44, 102044. doi:10.1016/j.msksp.2019.07.008
Hunt, E. R., Baez, S. E., Olson, A. D., Butterfield, T. A., & Dupont-Versteegden, E. (2019). Using Massage to Combat Fear-Avoidance and the Pain Tension Cycle. International Journal of Athletic Therapy and Training, 24(5), 198-201.
Liebenson, C. (2020). Rehabilitation of the Spine: A Patient-Centered Approach (3rd ed.). Wolters Kluwer.
Lewis, J. S., Cook, C. E., Hoffmann, T. C., & O'Sullivan, P. (2020). The Elephant in the Room: Too Much Medicine in Musculoskeletal Practice. The Journal of orthopaedic and sports physical therapy, 50(1), 1–4.
Lin, I., Wiles, L., Waller, R., Goucke, R., Nagree, Y., Gibberd, M., … O'Sullivan, P. (2020). What does best practice care for musculoskeletal pain look like? Eleven consistent recommendations from high-quality clinical practice guidelines: systematic review. British journal of sports medicine, 54(2), 79–86.
Miller, B. F., Hamilton, K. L., Majeed, Z. R., Abshire, S. M., Confides, A. L., Hayek, A. M., … Dupont-Versteegden, E. E. (2018). Enhanced skeletal muscle regrowth and remodelling in massaged and contralateral non-massaged hindlimb. The Journal of physiology, 596(1), 83–103. doi:10.1113/JP275089
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Walker, S. C., Trotter, P. D., Swaney, W. T., Marshall, A., & Mcglone, F. P. (2017). C-tactile afferents: Cutaneous mediators of oxytocin release during affiliative tactile interactions?. Neuropeptides, 64, 27–38. doi:10.1016/j.npep.2017.01.001
Walton, D. & Elliott, J. (2020). Musculoskeletal Pain – Assessment, Prediction and Treatment: A pragmatic approach. Handspring Publishing.
Waters-Banker, C., Dupont-Versteegden, E. E., Kitzman, P. H., & Butterfield, T. A. (2014). Investigating the mechanisms of massage efficacy: the role of mechanical immunomodulation. Journal of athletic training, 49(2), 266–273. doi:10.4085/1062-6050-49.2.25