The following is an excerpt from Erik Dalton’s book, Dynamic Body: Exploring Form Expanding Function, which features guest contributions from some of the leading thought leaders and practitioners in the massage profession.
Robert Schleip PhD, one of the leading figures in fascial research today, is the director of the Fascia Research Project, part of the division of neurophysiology at Ulm University in Germany. In this excerpt he looks at two common mechanisms for how massage therapists stretch fascia and demonstrates how neither is sufficient to explain the effects of massage on fascia. The rest of the chapter can be read in the Dynamic Body textbook, available as part of the Dynamic Lower Body home study program or as a standalone purchase.
The body-wide network of fascia is assumed to play an essential role in our posture and movement organization. It is frequently referred to as our organ of form. Many manual therapy approaches focus treatment on fascial tissues, and these approaches claim to alter the density, tonus, viscosity, or arrangement of fascia through the ap plication of manual pressure. It is also assumed that these changes are not merely temporary – that they last longer than a few minutes after the immediate application. The given explanations of the involved mechanisms usually refer to the ability of fascia to adapt to physical stress. How the practitioner understands the nature of this particular responsiveness of fascia does, of course, influence the treatment.
Unfortunately, fasciae are often referred to in terms of their passive mechanical properties alone. For example, experts often attribute sudden “tissue melt” to thixotropy. However, the results of recent studies seem to indicate that the application of temporary pressure – such as the pressure applied during a myofascial release session – would be unlikely to cause permanent tissue changes via such passive effects. In contrast, recent studies do seem to imply that tissue release and lasting changes may be due to an active contribution of the central nervous system and, particularly, fascial mechanoreceptors.
Thixotropy: The Gel-to-Sol Hypothesis
Many of the current training schools of myofascial manipulation have been profoundly influenced by Ida Rolf. In her hands-on work, Rolf applied considerable manual or elbow pressure to fascial structures to change their density and arrangement. Rolf proposed the theory that connective tissue is a colloid substance in which the ground substance can be influenced by the application of energy – heat or mechanical pressure – to change its aggregate form from a more dense “gel” state to a more fluid “sol” state. Typical examples of this are common gelatin or butter, which get softer with heat or mechanical pressure. This gel-to-sol transformation – also called thixotropy – has, in fact, been demonstrated in connective tissues as a result of the application of long-term mechanical stress.
However, the question arises: Is this model also useful in explaining the immediate short-term plasticity of fascia? In other words, what actually happens when a myofascial practitioner claims to feel a tissue release beneath the working hand? In most systems of myofascial manipulation, the duration of a particular “stroke” on a particular spot of tissue ranges from a few seconds to two minutes. However, practitioners often report sensing a palpable tissue release within a particular “stroke.”
Such rapid tissue transformation – less than two minutes – appears to be more difficult to explain with the thixotropy theory. As will be specified later, studies on the subject of “time and force dependency” of connective tissue plasticity suggest that either much longer amounts of time or significantly more force are required for permanent deformation of dense connective tissues.
Furthermore, the problem of reversibility arises. In colloidal substances, the thixotropic softening effect lasts only as long as the pressure or heat is applied. Within minutes after the heat or force application, the substance returns to its state of previous rigidity – think of the butter in the kitchen. The temporary nature of the achieved tissue softening is, therefore, not an attractive implication of this theory for the practitioner.
Piezoelectricity: Fascia as a Liquid Crystal
James Oschman and others have added piezoelectricity as an intriguing explanation for fascial plasticity. When an outside mechanical pressure temporarily separates the electric centers of neutrality on the inside of a crystal lattice, a small electric charge can be detected on the crystal’s surface. This effect is called piezoelectricity. Since connective tissue can be seen to behave like a “liquid crystal” these authors propose that the cells that produce and digest collagen fibers (fibroblasts) might be responsive to such electric charges. To put it simply: Pressure from the outside creates a higher electric charge, which stimulates the fibroblasts to alter their metabolic activity in that area.
However, the processes involved seem to require time as an important factor. The half-life span of non-traumatized collagen has been reported to be 300 to 500 days, and that of ground substance 1.7 to seven days. While it is definitely conceivable that the production of both materials could be influenced by piezoelectricity, both life cycles appear too slow to account for immediate tissue changes that are significant enough to be palpated by the working practitioner.
Fascial Plasticity: Traditional Explanations Insufficient
Both models, thixotropy and piezoelectricity, are appealing explanations for long-term tissue changes. Nevertheless, it seems they are not sufficient to account for the short-term plasticity of fascial tissues. Laboratory studies on the subject of time- and force dependency of connective tissue plasticity (in vitro, as well as in vivo) have shown the results outlined below. In order to achieve a plastic elongation of dense connective tissues, one needs to apply:
- either an extremely forceful stretch of three to eight percent fiber elongation, which will result in tissue tearing, inflammation, and other side effects that are usually seen as undesirable in a myofascial session. As an example, for an 18-millimeter-wide distal iliotibial band, such permanent elongation starts at 60 kilograms (kg).
- or it takes more than an hour (which can be taken at several intervals) with a less brutal one to 1.5 percent fiber elongation, if one wants to achieve permanent deformation without tearing and inflammation.
Figure 1 illustrates the typical relationships for short-term strain applications. Microfailure is seen as the breaking of some individual collagen fibers and some fiber bundles, resulting in a permanent (plastic) elongation of the tissue structure. This is usually followed by a cycle of tissue inflammation and repair. Based on measurements with different kinds of paraspinal tissues, A. Joseph Threlkeld, a professor of physical therapy, calculates that microfailure of most dense connective tissues occurs at around 224 to 1,136 N, which equals 24 to 115 kg. While high velocity thrust techniques might create forces within that range, it seems clear that the slower soft tissue manipulation techniques are hardly strong enough to create the described tissue response.
Recently, these propositions have been supported by studies from biomedical engineering research professor Hans Chaudhry and his team, demonstrating that the “palpable sensations of tissue release that are often reported by osteopathic physicians and other manual therapists cannot be due to deformations produced in the firm tissues of plantar fascia and fascia lata. However, palpable tissue release could result from deformation in softer tissue such as the superficial nasal fascia.”
In other words, while it may be possible to induce lasting changes in very soft connective tissues, such as in the areolar layer of the subcutis, the force/time dimensions used in myofascial release sessions are hardly sufficient to induce sustaining deformations in dense fascial sheets, which are usually the main focus of myofascial release sessions.
A simple thought experiment may be used for corroboration. During everyday life, the body is often exposed to loading magnitudes similar to the manual pressures in a myofascial treatment session. While body structure may adapt to long-term furniture use, it is almost impossible to conceive that adaptations could occur so rapidly that any uneven load distribution in sitting – for example, while reading this book – would permanently alter the shape of your pelvis within a minute. It seems essential, therefore, that we find additional explanations – besides the thixotropic and piezo electric ones – to account for the palpable tissue changes that occur in a treatment session.
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