Persistent pain is complex – if it was easy to explain it’d be easy to fix!
In my last post we talked about how the lymphatic-venous drainage system plays a key role in maintaining normal daily function of every tissue in the body and in so doing is one factor preventing persistent (also known as chronic) pain. In this post I will briefly outline another important system, the Fascial System, and in a subsequent post explore how it interacts with the Lymphatic-Venous Drainage system and the Nervous System to become a cause of chronic pain when not functioning properly.
What is Fascia?
Fascia is a type of connective tissue richly supplied with nerves that surrounds, binds and connects every tissue in the body, from outside to inside, top to bottom, right to left. It wraps around all our muscles, bones, blood vessels, brain and spinal cord, even our organs – basically it inter-connects everything in your body. Fascia varies from dense tough fibrous sheets (like the white stuff on the outside of a roast beef before it’s cooked), or it can be quite loose and disorganised white fibrous tissue (see the images / arrows below and notice the contrast between dense and loose fascia). It’s everywhere in your body! Human fascia is continuous with no discrete "start or end", it simply flows along into the next structure, leading to a host of interesting inter-connections throughout your entire body. As an aside, these connections can result in unexpected pain referrals and, to the surprise of many patients, treatment of fascial dysfunction at some distance from the symptoms often resolves their pain.
Fascia has received a massive surge in scientific interest in the past decade after it was found to be contractile (Yahia et al 1993). This was a surprising finding for many since fascia is not muscle – it does not contract in the same manner as muscle because it does not contain muscle cells per se. The primary cell of fascia is called a “fibroblast”, and under certain conditions the fibroblasts can transform into a “myofibroblast” which is capable of contraction (using a similar mechanism to smooth muscle contraction – smooth muscle is the type of muscle within your arteries, veins and intestines). Because the myofibroblast contains its own microfilaments that join to the external collagen fibres in fascia, the myofibroblasts are both able to detect and respond to mechanical strain in your tissues including via contraction which then imparts mechanical tension into the fascia (Tai et al 2021).
How strong is this contraction? Not strong as in lifting heavy weights with your skeletal muscles, but strong enough to reduce blood flow through the fascia, particularly in the low-pressure lymphatic-venous return system (Schleip et al 2019). It’s strong enough to help wounds close together, which is one of the normal functions of myofibroblasts you rely on every time you cut yourself. The myofibroblasts also secrete new collagen fibres (SCAR TISSUE) which if excessive causes FIBROSIS (very tight tough connective tissue scarring). This has been demonstrated in every tissue in the body including your organs, so getting a normal appropriate healing response involves normal myofibroblast activation and deactivation.
So what triggers myofibroblasts to form and contract? Any mechanic stress, injury, overuse or postural strain sufficient to cause some inflammation, can trigger fibroblasts to start to transform into myofibroblasts over a number of days. This is a normal process when faced with injury / excess load, and if everything heals normally then the myofibroblasts revert back to normal and fascial tension returns to normal. If the inflammatory chemicals become trapped around the cells because they are unable to be cleared away by the lymphatic-venous system, myofibroblast contraction will persist and perpetuate the tension in the fascial system.
Why does this even matter?
Read on to my next post, where I explain how the combined effects of poor lymphatic-venous drainage, persistent fascial tension, trapped inflammation, and activation of the sympathetic nervous system creates the perfect storm leading to a whole load of chronic pain.
References:
Schleip R et al (2019): Fascia Is Able to Actively Contract and May Thereby Influence
Musculoskeletal Dynamics: A Histochemical and Mechanographic Investigation. Frontiers in Physiol 10:article 336. doi: 10.3389/fphys.2019.00336
Tai Y et al (2021): Myofibroblasts: Function, Formation, and Scope of Molecular Therapies for Skin Fibrosis. Biomolecules 11: 1095. doi.org/10.3390/biom11081095
Yahia LH et al (1993): Viscoelastic properties of the human lumbodorsal fascia. J Biomed Engin 15:425-9.
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