Theoretical Research Into Pain and Its Effect on Movement Patterns

 "Movement is changed in pain. This presents across a spectrum from subtle changes in the manner in which a task is completed to complete avoidance of a function and could be both a cause and effect of pain/nociceptive input and/or injury." (Hodges & Smeets, 2015).

    I have been looking into the relationship between pain and movement. Since I suffer from chronic pain myself, I have noticed how over time my movement patterns have changed and adapted to facilitate pain-free movement. It is the protective body's response to the triggered nerves that try to prevent damage to the tissue by limiting and slowing down any related movement. I wanted to figure out if there are any resources discussing the change in human behavior, movement patterns, and anatomy when affected by chronic pain. Although the research is very limited, there are a few core theories that I am going to look at:

The first major theory is "The Vicious Cycle" (pain-spasm-pain cycle)

    "The vicious cycle theory hypothesizes that muscle activity increases in a stereotypical manner in pain, regardless of the task, yet sustained activity leads to ischaemia and accumulation of algesic agents, producing pain. A range of mechanisms underlying the increased activity has been proposed, including increased sensitivity of muscle spindles via inputs from group III and IV afferents (nociceptive muscle afferents) onto gamma motoneurons." (Hodges & Tucker, 2011).

The second theory is the "Pain Adaptation theory", proposed by Dr. James P. Lund

    It is often referred to as a hypothesis that challenges the mentioned "Pain-spasm-pain cycle" theory.

"Dr. Lund was the chief architect of the Pain Adaptation Model, which redefined the role of pain in clinical presentations, including persistent muscle pain conditions such as masticatory muscle pain, back pain, and fibromyalgia. The model challenged and displaced the prevailing Vicious Cycle Theory that was directing care for many pain conditions." (Stohler et al., 2009).

The theory, which is based on experimental observations, proposed that activity of muscles that are painful or that produce a painful movement reduces during voluntary efforts, whereas that of opposing/antagonist muscles increases. This adaptation reduces the amplitude and velocity of the painful movement, and it decreases the force produced by the muscle.

Based on experimental observations, the theory suggests that "the activity of muscles that are painful or that produce a painful movement reduces during voluntary efforts, whereas that of opposing/antagonist muscles increases." (Tucker, 2010). This adaptation results in the smaller amplitude and speed of the movement as well as a decrease in force produced by the muscle.

The new theory of motor adaptation to pain

    There is another theory, that includes elements of both mentioned hypotheses proposed by Professor Greg M. Murray and Christopher. C. Peck. It looks at the motor adaptation to pain from a more individualised perspective that depends on a specific case of pain. 

The theory consists of five key elements, "that expand on the basic premise that the adaptation to pain aims to reduce pain and protect the painful part, but with a more flexible solution than currently proposed." (Peck & Murray, 2008).

Adaptation to pain:

1. Involves redistribution of activity within and between muscles

2. Changes the mechanical behaviour such as modified movement and stiffness

3. Leads to protection from further pain or injury, or from threatened pain or injury

4. Is not explained by simple changes in excitability but involves changes at multiple levels of the motor system, and these changes may be complementary, additive, or competitive

5. Has short-term benefit but has potential long-term consequences due to factors such as increased load, decreased movement, and decreased variability

    The deeper understanding of the nervous system's response to pain and the motor adaptation that the human body performs encouraged me to explore this topic in practice. Since I have noticed primary changes in my posture and movement patterns that happen when I am experiencing chronic pain and after (compared to my healthy body's posture and ability), I decided to research this deeper in a studio, using my own body and experience as a tool for investigation.

Bibliography

    Balasch-Bernat, M., Willems, T., Danneels, L., Meeus, M., & Goubert, D. (2021). Differences in myoelectric activity of the lumbar muscles between recurrent and chronic low back pain: a cross-sectional study. BMC Musculoskelet Disord, 22(1), 756. https://doi.org/10.1186/s12891-021-04623-9

    Butera, K., Fox, E., & George, S. (2016). Toward a Transformed Understanding: From Pain and Movement to Pain With Movement. Physical Therapy, 96(10), 1503-1507. https://doi.org/https://doi.org/10.2522/ptj.20160211

    Hodges, P., & Smeets, R. (2015). Interaction Between Pain, Movement, and Physical Activity: Short-term Benefits, Long-term Consequences, and Targets for Treatment. The Clinical Journal Of Pain, 31(2), 97-107. https://doi.org/10.1097/AJP.0000000000000098

    Hodges, P., & Tucker, K. (2011). Moving differently in pain: A new theory to explain the adaptation to pain. Pain, 152(3), 90-98. https://doi.org/doi: 10.1016/j.pain.2010.10.020

    Lund, J. P., Donga, R., Widmer, C. G., & Stohler, C. S. (1991). The pain-adaptation model: a discussion of the relationship between chronic musculoskeletal pain and motor activity. Canadian journal of physiology and pharmacology, 69(5), 683–694. https://doi.org/10.1139/y91-102

    Merkle, S., Sluka, K., & Frey-Law, L. (2018). The interaction between pain and movement. Journal Of Hand Therapy, 33(1), 60-66. https://doi.org/https://doi.org/10.1016/j.jht.2018.05.001

    Meulders, A. (2019). From fear of movement-related pain and avoidance to chronic pain disability: a state-of-the-art review. Current Opinion In Behavioral Sciences, 26, 130-136. https://doi.org/https://doi.org/10.1016/j.cobeha.2018.12.007

    Murray, G., & Peck, C. (2007). Orofacial pain and jaw muscle activity: A new model. Pain, 21(4), 263-288. Retrieved 24 March 2022, from.

    Peck, C., & Murray, G. (2008). How does pain affect jaw muscle activity? The Integrated Pain Adaptation Model. Australian Dental Journal, 53(3), 201-207. https://doi.org/https://doi.org/10.1111/j.1834-7819.2008.00050.x

    van Dieën, J. H., Flor, H., & Hodges, P. W. (2017). Low-Back Pain Patients Learn to Adapt Motor Behavior with

Adverse Secondary Consequences. Exercise and Sport Sciences Reviews, 45(4), 223-229.

https://doi.org/10.1249/JES.0000000000000121