An in-depth discussion of the pain-relieving effects of manual therapy techniques is outside the scope of this book and the reader is referred to the work of Vicenzino & Wright (2002), who provide an account of the current evidence. Pain relief following the application of transverse frictions has been clinically observed and a number of working hypotheses are proposed to substantiate this. Farasyn (2007), for example, suggests that frictions applied to muscle releases stimulation of sensitized neurons and reduces referred pain.

The reduction in pain is experienced as a numbing or analgesic effect, i.e. a decrease in pain perceived by the patient who will often acknowledge this by saying you have ‘gone off the spot’. However, with faith in diagnosis and accurate knowledge of anatomy, this should be the signal to grade the friction more deeply to apply beneficial treatment appropriate to the lesion.

Following treatment the comparable signs can be reassessed and a reduction in pain and increase in strength is usually noted. This induced analgesia is utilized to allow the application of graded mobilization techniques in acute lesions. In chronic lesions, an initial analgesic effect is required through the application of a gentler grade of transverse frictions; the technique is then applied with increasing depth to provide a traumatic hyperaemia and pain relief to allow graded mobilization to be applied.

The traumatic hyperaemia induced by the application of deeper graded transverse frictions over a longer period of time in chronic lesions may produce analgesia through changes in the local microenvironment of the tissues via an increased blow flow. These changes may include removal of the chemical irritants that sensitize or excite local nociceptors, a decrease in local oedema and pressure, the production of local heat and facilitation of the repair process.

Pain modulation may be induced through several complex phenomena, including spinal and central nervous system mechanisms acting individually or in combination, to produce desired effects. The gate control theory proposed by Melzack & Wall in 1965 is a theory of pain modulation that affects the passage of sensory information at spinal cord level, especially nociceptive impulses. Within the spinal cord there are mechanisms which ‘open the gate’ to impulses provoked by noxious stimuli, and mechanisms which ‘close the gate’, thus reducing the awareness of noxious stimuli.

Pressure stimulates low-threshold mechanoreceptors, the A-beta fibres, that reduce the excitability of the nociceptor terminals by presynaptic inhibition, effectively ‘closing the gate’ on the pain. The A-beta fibres are myelinated, fast conducting fibres which basically ‘overtake’ the slow conducting fibres to reach the gating mechanism, closing it to incoming painful stimuli. The greater the mechanoreceptor stimulation, the greater the level of pain suppression (Bowsher 1994, Wells 1994). Put simply, rubbing a painful spot reduces pain, enabling the transverse frictions to be graded in depth, specific to individual lesions, and thus to produce their beneficial effects.

The reduction in pain achieved seems to be fairly long-lasting, possibly longer than expected. Transverse frictions, like rubbing or scratching the skin, are considered to be a form of noxious counterirritation that leads to a desired analgesic effect (de Bruijn 1984). Inhibition, which produces lasting pain relief, is believed to be through the descending inhibitory control systems via the periaqueductal grey area – the key centre for endogenous opioid analgesic mechanisms. Endogenous opioids are inhibitory neurotransmitters which diminish the intensity of the pain transmitted to higher centres (de Bruijn 1984, Melzack & Wall 1988, Goats 1994).

De Bruijn (1984) treated 13 patients with deep transverse frictions to various soft tissue lesions. The time required to produce analgesia during the application of deep transverse frictions was noted to be 0.4–5.1 min (mean 2.1 min) while the post-massage analgesic effect lasted 0.3 min–48 h (mean 26 h).

Carreck (1994) evaluated the effect of a 15-min general lower limb massage (effleurage and pétrissage) on pain perception threshold in 20 healthy volunteers and showed that the massage significantly increased the pain perception threshold for experimentally induced pain. Conversely, Kelly (1997), using deep transverse frictions on normal volunteers, reported no significant change in the pain pressure threshold, although there was an improvement in function that will be discussed below.

Massage in its various forms is considered to be a placebo, having a therapeutic effect on the psychological aspects of pain. There is no doubt that a professional attitude, including a thorough patient assessment and diagnosis, an explanation of the problem and the beneficial effects of the proposed treatment intervention, together with involvement of patients in their own recovery, has great effect. Transverse frictions as a form of massage may also have a placebo effect.

Transverse friction aims to achieve a transverse sweeping movement of the target tissues – muscles, tendons and ligaments – to prevent or eliminate adhesions (Wieting Cugalj 2004). This transverse movement, together with graded mobilization, discourages the stationary attitude of fibres that promotes anomalous cross-link formation. By combining transverse friction and mobilization in this way, the technique attempts to reduce abnormal fibrous adhesions and improve scar tissue mobility by encouraging normal alignment of soft tissue fibres (Brosseau et al 2002, Wieting Cugalj 2004, Lorenzo 2008). The therapeutic movement may facilitate the shear and gliding properties of collagen, allowing subsequent longitudinally applied stresses, through graded mobilization techniques, to stimulate fibre orientation towards enhanced tensile strength. In this way adhesion formation is prevented in acute situations and mobilized in chronic situations.

Friction potentially exists whenever two objects come into contact with each other, which is why it is important that the depth of application of transverse frictions should ensure that the therapist’s finger makes contact with the target tissue, albeit via the skin and superficial tissues. A shear force is one that attempts to move one object over or against another and is applied parallel to the contacting surfaces in the direction of the attempted movement. The greater the contact force via the therapist’s finger on the target tissue and/or the rougher the contacting surfaces, the greater the force of friction. Imagine rubbing your hands together; the harder you press, the greater the contact force and the greater the friction generated (Levangie & Norkin 2001). Friction generates heat and may therefore promote movement of the tissues by reducing pain and viscosity.

A therapeutic to-and-fro movement aims to mimic the function of the target tissue to prevent adhesive scar tissue formation in acute lesions and to mobilize established scarring in chronic lesions. For this reason, muscle bellies are placed into a shortened position to facilitate broadening of the muscle fibres and ligaments are moved across the underlying bone. In the case of tendons, transverse frictions aim to move the structures passively, either within the surrounding connective tissue or between a tendon and its sheath. Tendons in sheaths are therefore put on the stretch to allow mobilization of the sheath around the solid base of the underlying tendon.

When applied in the early inflammatory phase, gentle transverse frictions (approximately six sweeps) cause an agitation of tissue fluid that may increase the rate of phagocytosis by chance contact with the macrophages (Evans 1980). It is a useful treatment to apply in the acute inflammatory stage following injury, depending upon the irritability of the condition. It is applied in this ‘gentle’ manner before scar tissue formation has truly begun, but should be graded appropriately to avoid increased bleeding or disruption of the healing breach.

In an experiment to evaluate pain and range of movement in acute lateral ligament sprain of the ankle, the effect of transverse frictions together with Grade A mobilization was compared to Grade A mobilization alone (Kesson & Rees, unpublished work 2002). The experimental group received transverse frictions and Grade A mobilization, while the comparison group received Grade A mobilization alone. The sample size of 16 was too small to allow statistical significance or generalization but the experimental group showed a greater overall increase in range of movement and a greater overall decrease in pain on single leg standing than the comparison group. However, it was noted that two subjects experienced a decreased range of movement and four experienced increased pain on single leg standing in the experimental group. The mean number of days post-injury for the experimental group was 4.4 and if this trend were upheld in a larger trial it could have implications for assessing the appropriate time to apply transverse frictions in terms of assessment of irritability. The suggestion is that the appropriate time for applying transverse frictions and Grade A mobilization cannot be determined in terms of number of days post-injury, but should be assessed in terms of the injury sustained and the irritability of the lesion.

In the chronic inflammatory phase, deep transverse frictions produce therapeutic movement, increasing frictional forces and generating heat to soften and mobilize adhesive scar tissue. This prepares the structure for other graded mobilizations that aim to apply longitudinal stress.

Increasing the depth of transverse frictions, i.e. the contact between the therapist’s finger and the target tissue, together with an increase in time of the application of the technique to approximately 10 min produces a controlled traumatic hyperaemia and is used exclusively for chronic lesions. The hyperaemia is caused by the mechanical action of the technique (Brosseau et al 2002).

A superficial erythema (redness) develops in the skin through dilatation of the arterioles and it is assumed that the same reaction is occurring in the deeper tissues where the effect is required (Winter 1968). The area of redness that develops under the finger may also be slightly raised and warm (a wheal), indicating increased permeability of the capillary walls that allows tissue fluid to pass into the surrounding area (Norris 2004). Massage, which increases blood flow in this way, changes the microenvironment of the tissues, producing local heat and decreasing pain by facilitating the removal of chemical irritants which sensitize or excite local nociceptors. This may also produce a decrease in pain by facilitating the transportation of endogenous opiates.

The work of Gregory et al (2003), described above, indicated that transverse frictions applied for 10 min produced ultrastructural changes in skeletal muscle initially consistent with the inflammatory process and ultimately with the reparative process. The observation of the redness and the wheal following the application of 10 min transverse frictions may be sufficient to stimulate a controlled inflammatory reaction which could be responsible for boosting the repair process in chronic lesions. Applying appropriate graded mobilizations after the friction technique aims to ensure healing within the presence of movement and the production of a strong mobile scar.

Although no clinical evidence exists to support the exact timing of 10 min after achieving an analgesic effect, it is the approximate time taken to induce and observe the skin changes described. However, tenderness in the target and overlying tissues may be a product of the induced inflammatory response; therefore at least 48 h (possibly 6 days, see the work by Gregory et al described above) is recommended between the treatment sessions in chronic lesions, in order for the tenderness to subside. The work of Davidson et al (1997) and Gehlsen et al (1998) suggests that in chronic tendinopathy (i.e. a degenerative process) repair may occur in the absence of inflammation by increasing the number and activity of the fibroblasts. Their work suggests that greater fibroblastic proliferation and activity occur with deeper pressures, indicating the appropriateness of deeper graded transverse frictions in chronic lesions.

Although the traumatic hyperaemia may be desirable in chronic lesions, this is not the case in acute lesions where the response is already excessive. Gentle transverse frictions applied to acute lesions for approximately six sweeps after achieving an analgesic effect are performed with reduced depth and time to avoid producing this traumatic hyperaemia. Such patients are treated ideally on a daily basis, or as often as possible, to ensure healing within the presence of movement and to encourage the formation of strong mobile scar tissue.

The therapeutic movement achieved and pain relief induced by transverse frictions produce an immediate clinical improvement in function of the structure treated. This can be demonstrated by reassessment of the comparable signs immediately after treatment and provides an optimum situation for the application of other graded mobilizing techniques.

As discussed above, Kelly (1997) and Iwatsuki et al (2001) conducted studies which demonstrated improved muscle function in terms of strength of contraction, with Kelly also demonstrating increased range of movement.

In peripheral lesions, Grade A mobilization, either active or passive, produces a gentle soft tissue movement agitating tissue fluid in the acute inflammatory phase and facilitating the phagocytic action of the macrophages (Evans 1980). The movements are of small amplitude, slow, pain-free, without force and repeated often.

Peripheral Grade A mobilization will promote movement within connective tissue structures to prevent a stationary attitude of fibres. In the acute phase of inflammation, the movement should occur without stress or disruption of the healing breach. The patient is instructed to exercise up to the point of discomfort, but not into or through pain, and must understand the importance of this controlled, precise movement. In this way a critical amount of movement is applied to encourage function but not to delay healing.

The function of a muscle belly is maintained by performing active inner-range, isometric, pain-free contractions aiming to broaden muscle fibres. The function of a ligament is promoted by performing active pain-free movement, maintaining the ligament’s ability to glide over the underlying bone. In overuse lesions, e.g. tendinopathy, the patient maintains normal function by performing movement within the pain-free range and avoiding the painful movements.

Peripheral Grade A mobilization aims to impart sufficient longitudinal stress to promote orientation of collagen fibres within the existing parallel collagen weave. As acute lesions subside, and once it is judged that there is sufficient tensile strength in the wound, the patient may begin to ‘nudge’ pain to provide longitudinal stress but without disrupting the healing breach. Grade A mobilizations performed in this way are of short duration, are not forceful and are repeated often. This form of mobilization is appropriate for the repair phase of connective tissue injuries, and as progress is made an increasing range of movement is encouraged. In this way the developing scar tissue is stressed, not stretched (to avoid over-stressing the healing tissues), aiming to restore full functional range. Tissues which heal within the presence of movement in this way should not require ‘traditional’ stretching into the painful range.

Peripheral Grade A mobilization is applied early in the inflammatory phase to ensure that function is rapidly regained. Healing within the presence of movement promotes a return to function, i.e. form follows function. The range of movement is gradually increased, applying sufficient stress to the wound to promote orientation of fibres. Controlled mobilization of acute lesions should prevent the need for stretching tissue.

In chronic injuries, once the lesion is rendered pain-free by transverse frictions or corticosteroid injection, normal movement will promote remodelling and alignment of fibres and restoration of function. However, until signs and symptoms subside, it is suggested that overuse activity should be avoided in lesions aggravated by repetitive movements, and resisted exercise and stretching postponed until the scar tissue is fully mobilized and the selective tension tests pain-free.

To reduce a peripheral joint loose body (e.g. in the hip, knee or elbow) or a bony subluxation (e.g. carpal bone), a Grade A mobilization is performed under strong traction, the principal component of this technique, giving the fragment space to move.

In the early stages of arthritis, pain causes the joint to be held in a position of ease, restricting movement of some parts of the joint capsule. This promotes a disordered deposition of collagen fibres and the normal flexibility of the joint capsule is impeded by anomalous cross-link formation. The changes in the capsule contribute to contracture and the capsular adhesions severely restrict the range of movement, causing pain and altered function. The aim of treatment by Grade B mobilization is to lengthen the capsular contracture permanently, to restore normal movement.

Adhesions that develop within the capsule of a synovial joint tend to be tough and unyielding. The shoulder and hip joints commonly demonstrate this gross loss of function and respond well to Grade B mobilization, providing the joints are in a non-irritable state. However, the technique could be applied to any non-irritable capsulitis in which pain and loss of movement are clinical features. Characteristically the joint is limited in the capsular pattern, with the restricted movements demonstrating a ‘hard’ end-feel (see Ch. 1). Peripheral Grade B mobilization is aimed at restoring the movements limited in the capsular pattern.

Peripheral Grade B mobilization is applied at the end of available range, appreciating the end-feel and the patient’s pain response. To be successful, the end-feel should still have some elastic quality, but the sensation of muscle spasm may also be apparent as the technique is applied within a painful range. The technique is a slow, sustained and repeated stretch, performed at the end of available range for the duration of the patient’s pain tolerance. As soon as the end range position is released, an immediate relief of pain should be felt. If pain lingers at this stage, the joint may be too irritable and the technique inappropriate.

Successful treatment is dependent upon patient compliance as the management of the condition is long-term. Theoretically the tissue to be stretched needs to be taken into the plastic range to achieve permanent lengthening, with sufficient force applied to strain and break some of the collagen cross-links in the adhesive scar tissue, producing microfailure. However, as the capsular tissue possesses viscoelastic properties, this can be utilized to gain increased range of movement. The following factors relating to the behaviour of connective tissue under mechanical stress (see Ch. 2) can be applied to this mobilization, which is suggested for tough, unyielding capsular adhesions.

Prolonged immobilization produces joint contracture, with more involvement of the joint capsule than the soft tissues surrounding the joint (Usuba et al 2007). A static stretch of slow, sustained, low force, applied towards the end of the elastic limit of the scar tissue, utilizes the viscous flow phenomenon which enables the contracted scar tissue to creep or lengthen gradually (Amis 1985, Hardy & Woodall 1998, Usuba et al 2007).

Grade B mobilization is a static stretch applied to the patient’s pain threshold point. The increased length achieved is apparently due to cross-link disruption, fibre slippage and eventual structural changes (Hardy & Woodall 1998). Lengthening, under these circumstances, is inversely proportional to the velocity of the applied stretch with a slowly applied force meeting with less resistance or stiffness (it is easier to move slowly through a viscous medium). Hysteresis (the slower rate at which the structure recovers from the elongating force) may also play a role and can be linked to cyclical loading where subsequent applications of Grade B mobilization achieve a modest increment of increased length with each mobilization applied.

The structural changes occurring in the mobilized tissue may produce a low-grade inflammatory response and the patient should be warned about post-treatment soreness. The importance of continued movement to maintain the elongation achieved cannot be stressed enough, and the patient must be given an appropriate exercise programme to maintain the range achieved.

The optimum duration and frequency of the static stretch has yet to be determined, but the work of Brandy & Irion (1994) and Brandy et al (1997) suggests that in order to achieve an increase in range of knee flexion, a static stretch of 30 s applied to the hamstring muscles is sufficient. However, their studies fall short of determining how long the increased flexibility in the muscles lasted.

The application of heat relieves pain and lowers the viscosity of collagen tissue, allowing a greater elongation of collagen tissues for less force. Warren et al (1971) considered the effect of temperature and load on elongation of the collagen fibre structure of rat tail tendon. A range of loads was applied at selected temperatures and the greatest elongation with least microdamage was achieved with lower loads at the higher therapeutic temperatures. The mechanism of a combined application of temperature and load affected the viscous flow properties of collagen and increasing the temperature of a structure allowed lower sustained loads to achieve greater elongation (Warren et al 1971, Usuba et al 2007).

Raising local temperature to between 40 and 45°C (40°C is the temperature of a very hot bath) achieves this useful therapeutic effect. Ultrasound can be applied to produce this thermal effect as it has a preference for heating collagen tissue (Low & Reed 1994). Usuba et al (2007) found from their previous studies that heat combined with stretching was more effective than stretching alone and, to achieve its best effects, heat should be applied concurrently with the Grade B mobilization. However, for practical purposes it is usually applied beforehand.

In arthritis, the inflammatory changes involve both the synovial lining of the joint and the fibrous capsule. The capsule develops small lesions that undergo scar tissue formation, producing adhesions or capsular thickenings. The adhesions are affected by joint movement which, through abnormal tension, stimulates the free nerve endings lying in the capsule, producing mechanical pain. The nerve endings also respond to the chemical products of inflammation – histamine, kinins and prostaglandins. Impulses are transported in the non-myelinated C fibres and a ‘slow’, aching, throbbing pain is produced which is poorly defined, i.e. chemical pain (Norris 2004). The pain and associated involuntary muscle spasm reduce movement, allowing healing to occur in a shortened position and resulting in reduced function.

Sustained or repetitive passive joint movement may modify the firing responses in large-diameter mechanoreceptor joint afferents, particularly when the capsular stretch is maintained at or near the end of range. This presents an explanation that accounts for the pain-relieving effects of end-range mobilization, including passive Grade B stretching techniques as well as manipulation.

The permanent lengthening achieved by Grade B mobilization reduces the mechanical stress and therefore inflammation, which in turn relieves pain. Normal movement patterns are restored. This provides a stimulus to fibre alignment and orientation within the collagen weave.

The increase in joint range and pain relief achieved by peripheral Grade B mobilization improves overall function. However, the gradual onset of loss of movement through capsular contraction can considerably alter movement patterns. Careful assessment of the patient is necessary and a treatment programme planned which considers all components of the dysfunction, including altered biomechanics, muscle imbalance and neural tension.

Peripheral Grade B mobilization is not used exclusively for capsular contractures. In chronic muscle, tendon and ligament lesions, adaptive shortening may be part of an overall dysfunction. The shortened tissues can be stretched by applying the principles of Grade B mobilization, both by the therapist and as a home treatment regime. Grade B mobilization is applied once the structure has been rendered functionally pain-free by deep transverse frictions and negative findings are established on examination by selective tension. Contracted tissue has an influence on neural structures; however, neural tension techniques fall outside the scope of this text.