Friday, August 24, 2012

Mechanical Forces

Application of mechanical forces during massage.  A, Compression. B, Tension. C, Bending. D, Shear. E, Torsion. F, Combined loading: compression + tension. G, Combined loading: tension + bend + torsion. H, Combined loading: compression + bend + torsion.

From Fritz: Clinical Massage in the Healthcare


In this second post in the series  about Advanced Massage we will explore what massage methods do to the body tissues.  At the foundational base massage introduces mechanical forces into the tissues and then the body needs to figure out how to respond to the force .  All massage methods regardless of name can be described by the mechanical forces introduced and how the application is modified by when it is applied, how long, what speed, what direction, the depth of pressure, etc.  I suggest you get some modeling clay and observe what occurs when you apply the mechanical forces.  Does the clay get warmer,  colder, stretchy, longer, shorter, etc.

Actions that involve pushing, pulling, friction, or sudden loading (e.g., a direct blow) are examples of mechanical force. Mechanical forces can act on the body in a variety of ways. The different types of mechanical force and the ways they are applied therapeutically are important aspects of massage.

The five kinds of force that can affect body tissues are compression, tension, bending, shear, and torsion. Not all tissue is affected the same way by each type of force. We will look at each of the five types of force, the different ways they can cause tissue injuries, and the ways they produce important therapeutic benefits when applied by a skilled massage practitioner.



Compressive forces occur when two structures are pressed together. Compressive force is a component of massage application and is described as depth of pressure. This kind of force may be sudden and strong, as with a direct blow (percussion), or it may be slow and gradual, as with gliding strokes. The magnitude and duration of the force are important in determining the outcome of the application of compression .

Some tissues are quite resilient to compressive forces, and others are more susceptible. Nerve tissue is an interesting example. Nerve tissue can withstand a moderately strong compressive force if the force does not last long (e.g., a sudden blow to the back of your elbow that hits your “funny bone”). However, even slight force applied for a long time, as occurs with carpal tunnel syndrome, can cause severe nerve damage. The practitioner must take this into account when determining the duration of a massage application that involves compression over nerves. Compressive force should not be maintained on a specific area for extended periods during massage. Generally, a compressive force need not be sustained for longer than 15 seconds to achieve results.


Ligaments and tendons are quite sturdy and resistant to strong compressive loads. Muscle tissue, on the other hand, with its extensive vascular structure, is not as resistant to compressive forces. Excess compressive force can rupture or tear muscle tissue, causing bruising and connective tissue damage. This is a concern when pressure is applied to deeper layers of tissue. To prevent tissue damage, the practitioner must distribute the compressive force of massage over a broad contact area on the body; the more compressive force used, the broader the base of contact with the tissue.

Compressive force is used therapeutically to affect circulation, sensory and autonomic nerve stimulation, nerve chemicals, and connective tissue pliability.



Tension forces (also called tensile forces) occur when two ends of a structure are pulled in opposite directions. This is different from muscle tension. Muscle tension is created by excess muscular contraction, which results from an increase in motor tone or an increase in tissue density caused by fluid accumulation and connective tissue changes (muscle tone). Muscles that are long as a result of being pulled apart are affected by tensile force. Certain tissues, such as bone, are highly resistant to tensile forces. An extreme amount of force is required to break or damage a bone by pulling its two ends apart. Soft tissues, on the other hand, are very susceptible to tension injuries. In fact, tensile stress injuries are the most common soft tissue injuries. Such injuries include muscle strains, ligament sprains, tendinitis, fascial pulling or tearing, and nerve traction injuries (i.e., sudden stretching of nerves, such as occurs in whiplash).

Tension force is used during massage with applications that drag, glide, lengthen, and stretch tissue to elongate connective tissues and lengthen short muscles .



Bending forces are a combination of compression and tension. One side of a structure is exposed to compressive forces as the other side is exposed to tensile forces. Bending occurs during many massage applications. Force is applied across the fiber or across the direction of the muscles, tendons or ligaments, and fascial sheaths. Bending forces rarely damage soft tissues; however, they are a common cause of bone fractures. Bending force is very effective in increasing connective tissue pliability and affecting proprioceptors in the tendons and belly of muscles.


Shear is a sliding force, and significant friction often is created between the structures that slide against each other. The massage method of friction uses shear forces to generate physiologic change by increasing connective tissue pliability and creating therapeutic inflammation. However, excess friction (shearing force) may produce an inflammatory irritation that causes many soft tissue problems .




Torsion forces are best understood as twisting forces. Massage methods that use kneading introduce torsion forces and target connective tissue changes and fluid movement.

Application of torsion force to a single soft tissue structure is not very common and is rarely the cause of significant tissue injury. Torsion force applied to a group of structures (e.g., a joint) is much more likely to be the cause of significant injury. For example, when the foot is on the floor and the individual turns the body, the knee as a whole is exposed to significant torsion force .


Massage Manipulations and Techniques (Mode of Application)

The methods of massage introduce one or a combination of the five types of mechanical force into the body to achieve a therapeutic benefit .  As mentioned, this process is influenced by the quality of touch, depth of pressure, drag, duration, speed, rhythm, and frequency. Appropriate use of mechanical force is necessary. If insufficient force or the wrong type of mechanical force is used, the application will not be effective; conversely, excessive or inappropriate use of force can damage tissues.


The variety of massage and bodywork modalities in the profession  can be clarified by describing what is done during the application, using qualities of touch, mechanical forces, and mode of application. For example, the method called active release is compression applied by the massage therapist and tension force that occurs as the client moves the area.  

A trained massage therapist should be able to modify the massage application from surface to deep, fast to slow, and long to short, as appropriate, based on the client's individual needs. The intention and outcome of the massage application appropriately influence fluid movement, nervous system function, musculoskeletal function, and connective tissue pliability in both acute and chronic conditions. Our attention to the client is based on an intent to serve our clients in a focused and compassionate manner.

Advanced massage is skillful use of the basics.  


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