Post-Isometric relaxation relates to the effect of subsequent relaxation, experienced by a muscle, or group of muscles, after brief periods, during which an isometric contraction is performed.When a muscle is isometrically contracted, its antagonist will be inhibited, and will relax immediately following this. Thus, the antagonist of a shortened muscle, or group of muscles, may be isometrically contracted, in order to achieve a degree of ease and additional movement in the shortened tissues. Shortening of muscle is a self-perpetuating phenomenon, the muscle is incapable of returning to a normal resting length as long as this continues. Whilst the effective length of the muscle is thus shortened, it is nevertheless capable of shortening further. The pain factor seems related to its inability thereafter, to be restored to its anatomically desirable length. The conclusion is that much joint restriction is a result of muscular tightness and shortening.
Damage to any muscle results in the patient either (1) compensating for the damaged muscle by retraining other muscles to perform the same motion, or (2) changing the motion drastically in order to reduce the work required of the damaged muscle (Lieber 1992).
The health of any joint is dependent upon a balance in the strength of its opposing muscles. If for any reason a flexor group loses part, or all of its function, its opposing extensor group will draw the joint into a hyperextended position, with abnormal stress on the joint margins. Lack of attention to the muscular component of joints in general, and spinal joints in particular, results in frequent inappropriate treatment of the joints thus affected. Correct understanding of the role of the supporting musculature would frequently lead to normalization of these tissues, without the need for heroic manipulative efforts.
Where is damage to the soft or hard tissues of a joint a factor?
In such cases the periarticular and osteophyte changes, all too apparent in degenerative conditions, are the major limiting factor in joint restrictions. If, due to injury, inflammatory processes occur as a more serious evolution takes place, as inflammatory exudate triggers the process of contracture, resulting in shortening of connective tissue. This means that following injury, two separate processes may be occurring simultaneously: scar tissue development in the traumatized tissues and also fibrosis in the surrounding tissues. In both situations, however, Postisometric relaxation may be useful, although more so where muscle shortening is the primary factor.
Healthy, well-coordinated muscles receive and respond to a multitude of signals from the nervous system, providing the opportunity for coherent movement. When, through overuse, misuse, abuse, disuse, disease or trauma, the smooth interaction between the nervous, circulatory and musculoskeletal systems is disturbed, movement becomes difficult, restricted, commonly painful and sometimes impossible. Dysfunctional patterns affecting the musculoskeletal system which emerge from such a background lead to compensatory adaptations and a need for therapeutic, rehabilitative and / or educational interventions.
The use of both neuro-muscular technique and muscle energy technique, is indicated in such a situation, as a means of breaking the cycle and, initially, relaxing the contracted muscles.
The body is a unit; all parts function in the context of the entire organism. Disease is a reaction of the organism as a whole. Abnormal structure or function in one part exerts abnormal influence on other parts and, therefore, on the total body economy. The organism has the inherent capacity to defend itself, to repair itself, and to resist serious upsets in external impact.
Post-Isometric Myorelaxation (PIR)
Post isometric relaxation (PIR) techniques consist of isometric tension for 15-25 seconds followed by passive stretching. The idea of PIR is such that at the time of isometric constriction, unaffected parts of the same muscle stretch pathologically affected parts. Post isometric stretching stimulates Golgi organ, which, in turn, additionally relaxes the affected muscle. This method, along with trigger points therapy, muscular mobilization and fascia release has significant healing power. I would also like to point out that all methods that I mentioned above, are equally important in treatment of muscular pathologies and must be part of comprehensive treatment. PIR methods have many possible variations that will affect the results. For example, the muscle length at starting position; the effort of the client or therapist; the duration of the contraction; whether the contraction is pulsed or single; the number of repetitions of the contraction; whether the position changes with each repetition, i.e. moving to tissue tension; the direction of effort, i.e. whether it is an eccentric or concentric contraction; client breathing and eye movements in the direction of the force; type of resistance, i.e. gravity, therapist or immovable object. These variables need to be combined and controlled depending on the particular needs of the case.
The method gives immediate pain relief in 94%, lasting pain relief in 63%, as well as lasting relief of point tenderness in 23% of the sites treated.(Myofascial pain: relief by post-isometric relaxation, Lewit K, Simons DG, Arch Phys Med Rehabil. 1984 Aug;65(8):452-6) Pain was relieved in both the muscle itself and at tender insertion points. The treatment of muscular pathologies is one of the most difficult challenges for healthcare practitioners. The difficulties that health-care professionals face is due to the fact that no physical therapy equipment or muscular relaxation and anti-inflammatory medication can cause energy balance within pathologically hypertonic muscles.
References: L. Chaitow, 2006, Muscle Energy Techniques L. Chaitow, J. Walker Delany, 2002, Clinical Application of Neuromuscular Techniques