HOW MASSAGE THERAPY HEALS THE BODY. PART II: Streaming Potentials
This is Part II of the article which reviews the scientific data about the healing effects of massage therapy. I think it is time to base massage therapy on 21st century science. In Part I we discussed, based on the scientific data, how mechanical stimuli in the form of massage strokes are able to change the bioelectricity in the soft tissue affected by the trauma or pathological process.
The ability of the massage practitioner to generate piezoelectrical potentials in the soft tissue and restore fixed electric charge of the collagen molecules are the cornerstones of the healing effect of massage therapy. Please be sure that you read Part I of this article in the January-February issue of Journal of Massage Science. Diagram 1 summarized scientifically proved local effects of massage therapy on the human body. To replay the diagram please click at the beginning of the sliding bar (blue line) located just below the diagram.
In this part of the article we will discuss other equally important healing mechanism triggered by massage therapy – formation of streaming potentials. This phenomenon is barely known to massage practitioners and educators despite the fact that it plays a very important role in the restoring of normal bioelectricity in the soft tissue locally and client’s body in general.
Let’s define the phenomenon of streaming potentials. In the neutral solution for example distilled water if electrically charged particles flow right next to the fixed object with the opposite electric charge the streaming potentials are generated and they can be recorded. The faster mobile particle moves next to the fixed object the stronger electric potentials are generated.
The late 1960’s were the golden age of discoveries in the electrophysiology of the body including the electrical properties of the soft tissue and circulation. This is when the streaming potentials were originally detected.
Sawyer et al., (1966) observed and measured the streaming potentials in aorta and vena cava where electrically charged particles in the blood rush with great speed carried by blood flow. These streaming potentials are the result of electrically charged particles (Na, Cl, K) flow with the blood along the endothelial cells which line the inner surfaces of the vessels. In such case the endothelial cells act as fixed objects with the electric charge opposite to the charge of the particles which flow by. As the original scientific paper reported, and as was confirmed by other studies, the inner surface of the vessels has more negative charge with respect to the blood which exhibits positive charge while it flows through the same vessel. The authors also measured the streaming potentials in aorta and vena cava and found that they range or are ranged between 0.1 and 0.4 v. These numbers approach the upper limit of electric potentials for any biological system.
The Diagram 2 presents the formation of the streaming potentials in the large artery.
In the beginning, the diagram shows the split section of the large artery with blood flow. Red ovals are erythrocytes. As you may see, the arterial walls have a slightly negative charge. This fact is indicated by the ‘-‘ symbols in the diagram. Let’s look, as an example, on the electrical outcomes of single sodium (Na) ion (white circle with ‘+’ symbol) flowing with the blood flow along the artery. While passing along the negatively charged arterial walls this ion of sodium will generate streaming potentials as long as blood flow moves it along the arterial walls.
Let’s take, as an example, the middle part of our artery and, as you may see on the diagram the sodium ion generates the streaming potentials (dashed black double arrows) while passing next to the negatively charged arterial walls.
This diagram illustrates only one tiny fraction of entire event because in real life the same sodium ion will trigger the streaming potentials while passing along the entire vessel. The blood continues to move all sodium ions as well as other positively charged particles along the vascular walls and all positively charged particles will contribute to the formation of the streaming potentials which can be registered and recorded. The quicker blood flows the stronger streaming potentials. This is why they were ordinally detected in the aorta and vena cava where the blood flow is fastest. Later, the weaker streaming potentials were detected in the smaller arteries and veins as well.
To the great surprise of the scientific community in 1968, Anderson and Eriksson reported the existence of the streaming potentials in the soft tissue. As we discussed in Part I of this article the collagen is the most abundant protein in the body and it forms the framework for every type of soft tissue and organs and also serves as a main repair substance. Each collagen molecule is dipole (see Diagram 3 and 4), i.e. it has two oppositely charged ends and each molecule has so-called fixed electric charge which changes as a result of trauma or disease. The collagen molecules in every tissue or organ located in extracellular space (i.e. spaces between cells) which is filled with interstitial fluid. Thus each collagen molecule is a fixed structure which is surrounded by liquid (i.e. interstitial fluid) which constantly moves.
The interstitial fluid carries a variety of particles which are neutral, positively or negatively charged. As scientific studies show the flow of the particles with an electric charge opposite to the charge of collagen molecules triggers very weak streaming potentials at the moment these particles are passing near either end of the collagen molecule (Lee et al, 1979).
These streaming potentials are weaker than streaming potentials detected in the large vessels just because interstitial liquid moves particles with slower speed when compared to the blood which carries them faster inside the vessel. As I mentioned above the magnitude of streaming potentials depends on the speed with which the mobile particles move along the fixed objects with the opposite charge. The faster movement produces stronger streaming potentials and vice versa. The streaming potentials also depend on the pH in the soft tissue (Gross, Williams, 1982) and permeability of the tissue (Sander, Nauman, 2003).
Despite the fact that streaming potentials which are formed in the soft tissues are weak they are one of the critical factors in maintaining the correct electrical balance in the tissue and organs. They also support the fixed electric charge of collagen molecules within their physiological range. This is another important function of the streaming potentials which has direct impact on the healing process. As we discussed in Part I of this article, the healing of injury or pathological abnormality in any organ or tissue starts with the restoration of the fixed electric charge of the collagen molecules.
For example, the first reaction of the body to trauma or disorder is interstitial edema or accumulation of the fluid in the spaces between cells. One of the first outcomes of this edema is abnormal changes in the fixed electric charge of the collagen molecules. On the contrary, the healing in the affected area will always start with the decrease of interstitial edema first. As soon as interstitial edema decreases and proper microcirculation is restored the fixed electric charge of collagen molecules slowly normalizes, and this is the first critical step in a chain of event which finally produces the healing.
As every therapist who practices Lymph Drainage Massage (LDM) knows the interstitial fluid constantly moves and later forms the lymph which helps to drain the waste products from the tissue and organs. One of the goals of LDM is to enhance the formation and drainage of the lymph by enforcing the movement of the interstitial fluid. Thus, the stimulation of the movement of the interstitial fluid by LDM as well as any other types of massage strokes is an established scientific fact.
As a result of massage strokes the practitioner stimulates the movement of the interstitial fluid which starts to carry the electrically charged particles faster. This increase in the speed of the movement of electrically charged particles produces stronger streaming potentials and this fact alone is a very important issue for preventive and medical impact of massage therapy on the human body. The increase in the speed flow of interstitial fluid can be achieved only if the practitioner steadily increases the interstitial pressure (i.e., pressure in the spaces between cells). We will discuss this important issue at the end of this article.
Let me now illustrate the concept of streaming potentials with the help of Diagrams 3 and 4. Diagram 3 illustrates the physiological formation of the streaming potentials in the soft tissue (Andersson.and Eriksson 1968).
At the beginning of the diagram you can see an arch line which indicates the skin surface and the collagen molecule (yellow oval) which is dipole. The blue dots indicate the positively charged particles while the red dots indicate the negatively charged particles. These particles are the remains of proteins, glycoproteins, individual amino acids etc. which are carried by the interstitial fluid to the nearest lymph vessel. Electrically these particles can be neutral, positively or negatively charged.
As soon as you activated the diagram it will first indicate the direction of the flow of interstitial fluid (thin black dashed arrow). This flow will slowly move the negatively and positively charged particles. When the negatively charged particles pass next to the head of the collagen molecule the weak streaming potentials will be generated. These electric potentials are indicated by the thin, dashed double arrows.
Diagram 4 illustrates the formation of the streaming potentials in the same soft tissue while the massage strokes are applied.
The diagram starts with the repeating application of massage strokes in the direction of the drainage. It increases the flow of the interstitial fluid (thick dashed doble black arrows). The stimulated flow of the interstitial fluid moves the negatively and positively charged particles with the greater speed when compared to the regular drainage presented on the previous diagram. As a result of the faster movement of the negatively charged particles around to the head of the collagen molecule, which is positively charged, the stronger streaming potentials are formed. These electric potentials are presented by the thick double arrows.
Theoretical value of streaming potentials’ concept for the massage practitioners
Let’s consider that the practitioner relies in his or her practice on the preventive role of massage therapy. In such case the local mechanisms of the massage therapy will include the formation of the streaming potentials in the massaged tissue and this effect will greatly assist the client in maintaining health and prevent possible trauma.
For example, your session of therapeutic or sports massage conducted regularly on the exercise enthusiast will maintain the proper elasticity of his soft tissue and prevent strains or sprains. How will you do that? The information we discussed in this article tells you that normal response of the tissue to excessive training routine is low grade interstitial edema after exercise and it slowly changes the fixed electric charge of the collagen molecules. This is one of the reasons for the soft tissue to develop tension, lose elasticity and finally be traumatized.
The generation of stronger streaming potentials during the massage session will quickly restore and maintain the fixed electric charge of the collagen molecules within physiological range and it will keep collagen fibers more elastic and soft tissue flexible. Thus, your regular massage sessions will prevent possible injury in your client and he or she will greatly appreciate your services if you will be able to explain what exactly you are doing using proper scientific information rather than empty statement about healing energy.
Let’s look on another scenario when the practitioner has based his or her practice on medical aspects of massage therapy. The client was injured during a basketball game and suffers now from the Chronic Tendinitis of the Achilles Tendon. Proper medical massage protocol especially at the beginning of the therapy will decrease the local edema among other important healing factors. One of the first outcomes of increase of the drainage from the injured tendon and decrease of the local edema is restoration of the fixed electric charge of collagen molecules by generation of the stronger streaming potentials in the injured area. Only after this process is triggered the inflamed tendon will response to your therapy.
Practical value of streaming potentials’ concept for the massage practitioners
The last topic I would like to address in this article is the practical value of information we have just discussed. There are reasonable concerns the reader may have. Yes, it is great that I know now about streaming potentials, but what is practical meaning of all this information except its purely theoretical value?
Let me answer this hypothetical question by addressing just one practical meaning of the concept of streaming potentials. To start please observe the direction of the strokes and pressure distribution during your basic therapeutic massage routine. Your strokes:
1. Must be directed only along the lymph drainage. Back and forth movements of the hands along the massaged segment with the same pressure don’t generate stronger streaming potentials in the soft tissue. To engage this mechanism and maintain or restore normal electrophysiology of the soft tissue the practitioner must slowly increase the interstitial pressure through repetitive application of the strokes in the direction of the drainage. This increase is possible only if the pressure is applied in the direction of the drainage.
2. To maintain the constant contact with the massaged segment while executing strokes the practitioner must alternate pressure during application of long strokes. Any pressure must be used only in the direction of the drainage while coming back to the starting point of the strokes should be done only with very light touch just to maintain in the client the sensation of your constant contact with the massaged segment.
The video below illustrates these two important points. First part of the video below shows the application of effleurage strokes which generate low quantity and magnitude of streaming potentials because the practitioner’s hands move back and forth along the massaged segment with a similar degree of applied pressure. The second part of the video shows the same effleuarge strokes applied in the correct regime when pressure is applied only during the part of the stroke which coincides with the direction of the lymph drainage. In this case the strokes steadily increase the interstitial pressure and generate the strongest streaming potentials in the massaged tissue.
If you are already using these two basic principles and generate streaming potentials correctly this article will scientifically justify your work. If you don’t, change your routine because you are losing an important ally to your work – streaming potentials.
You will find another practical outcome of this article as soon as you start to share this information with your clients or colleagues. Real science is the fastest way to build your practice based on the respect and admiration to your expertise by your clients, patients or other health practitioners whom you may use as a great referral source.
Gross D., Williams W.S. Streaming Potentials and the Electromechanical Responce of Physiologically-Moist Bone. J. Biomechanics. 15(4):277-295, 1982
Lee R.C., Grodzinsky A.J., Glimcher N.J. The Electromechanics of Normal and Chemically Modified Articular Cartilage. In: Electrical Properties of Bone and Cartilage. Edited by Brighton C.T., Black J., Pollack, S.R. ‘Grune&Stratton’ New York, 1979
Sander E.A., Nauman E.A. Permeability of Musculoskeletal Tissues and Scaffolding materials: Experimental Results and Theoretical Predictions. Crit Rev Biomed Eng. 31(1-2):1-26, 2003
Sawyer P.N., Himmelfarb E., Lustrin I, Ziskind H. Measurement of Streaming Potentials of Mammalian Blood Vessels, aorta and vena cava. In:vivo. Biophys J. Sep; 6(5):641-651, 1966
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