MET of Quadratus lumborum
I accept that there are other models of MET – and that the approaches I describe below have changed since I first wrote on the subject over 30 years ago,  and will continue to change as research and clinical experience guides our knowledge towards better understandings of the physiological processes involved.
Some elements in the descriptions below involve a re-emphasis of aspects of MET methodology that seem to have been lost – most notably the concept of the ‘feather-edge’ barrier – the very first sign of resistance noted as tissues are taken towards their end-of-range. Many practitioners I have observed seem to feel that the end-of-range means as far as possible without pain – and this is just not the case.
Another feature that has largely been lost in MET teaching and use is employment of pulsed MET – and this most useful, gentle and effective mode of MET is described below.
Muscle Energy Technique [MET] is defined as a form of soft-tissue treatment in which the patient’s muscles are actively used, on request, from a precisely controlled position, in a specific direction, and against a distinctly executed therapist-applied counterforce. The key defining element of MET is the use of an isometric contraction before subsequent stretching or movement of restricted tissues.
MET is used to treat soft tissue or joint dysfunction, usually as part of a sequence of modalities, but sometimes alone. Some MET variations utilize isotonic eccentric contractions, where tissues are slowly stretched during a contraction. Variables include the degree of force used in the isometric contraction, the length of time this is sustained, for example five seconds or less than a second, the direction of applied force, for example, toward a restriction barrier or away from it, the degree of movement or stretching following the contraction, whether the altered position achieved is sustained or brief, and how many contraction repetitions are involved. Certain aspects of MET can be taught for safe self-application. 
Muscle Energy Technique (MET) was developed in the USA by osteopathic physician F Mitchell Sr. who first described MET in 1948, following exposure to the ideas of fellow osteopath, TJ Ruddy [Mitchell 1948]. Ruddy encouraged patients to actively participate in mobilization and manipulative procedures, rather than those processes being purely passive. Refinements of the methods were later developed by Mitchell’s son, F Mitchell Jr., as well as by Czech physician K Lewit, who worked to minimize the amount of force employed, as well as the direction and duration of isometric contractions: the basic MET precursor to subsequent movement or stretch. MET has been refined and systematized since, and has continued to evolve, with contributions by many practitioners from different professions, mainly in the treatment of shortened or weakened muscles and restricted joints. A recent revival in the interest of Ruddy’s early (1950s) work has led to the development of a rhythmic, ‘pulsed’ form of MET that offers the benefits of regular MET, together with proprioceptive rehabilitation [Ruddy 1961, Chaitow 2006]
Therapeutic aim or mechanism
In its period of early development, the mechanisms operating when Muscle Energy Technique (MET) was employed were ascribed to either post-isometric relaxation (PIR), affecting the tissues that had just been contracted isometrically, or reciprocal inhibition (RI), affecting the antagonists to the tissues that had contracted. PIR and RI are now seen to only partially explain the benefits of MET [Fryer & Fossum 2009]. Instead, the term ‘increased tolerance to stretch’ has been coined to describe (but not explain) the increased ease with which relatively pain-free joint and soft tissue motion is achieved following mild isometric contractions [Fryer 2006].
MET has two simultaneous therapeutic objectives, the first being pain modification. This is partially achieved by nociceptive inhibition, via both ascending and descending neurological pathways, following activation of muscle and joint mechanoreceptors during isometric contractions. At the same time, muscle contraction stimulates fluid flow so increasing drainage from interstitial spaces, reducing concentrations of pro-inflammatory cytokines, and thereby modulating peripheral pain receptors. It is now also known that during contractions, endogenous pain-inhibiting substances are released, including endocannabinoids, enkephalins, and endorphins [McPartland 2008]. A second primary objective of MET involves enhanced mobility, and one mechanism whereby this is achieved relates to the stretching of the series of elastic components of sarcomeres during isometric contractions, increasing their length, particularly if active or passive stretching follows after MET [Lederman 1997]. A further mechanism involves reduction in the fluid content of fascial structures following muscle contractions, leading to a temporary increase in the ease of movement of associated muscles or joints [Klingler et al 2004].
Indications for treatment
Based on clinical studies, Muscle Energy Technique (MET) is indicated as a form of therapeutic intervention in conditions where there is evidence of musculoskeletal soft tissue or joint restriction that manifests with reduced range of motion (ROM) and/or pain [Fryer 2006]. Such dysfunctional conditions appear amenable to MET, whether they are acute or chronic. MET is also suitable for combining with other manual therapy modalities, such as Positional Release Technique (PRT) and Neuromuscular Therapy (NMT) in the integrated treatment of myofascial trigger points for example (for more information, see ‘Trigger Point Release Therapy’) [Nagrale et al 2010]. There is increasing evidence of the usefulness of methods that involve isometric contractions, such as MET, in chronic pain conditions [Bement et al 2011].
Advantages and benefits
The modern use of Muscle Energy Technique (MET) in clinical settings can be seen to have numerous advantages as a therapeutic tool, since it is economical in terms of the time involved and the degree of physical effort required when used in the treatment of restricted joints or soft tissues. Because results are commonly rapid, as demonstrated by reduced discomfort and increased mobility, benefits are likely to soon become apparent to both patient and therapist.
When used in its rhythmic pulsed mode, MET also offers proprioceptive rehabilitation features, enhancing motor control, something that purely passive manual therapy methods cannot produce. It is thought that MET may enhance proprioception, motor control, and motor learning, because it involves the active and precise recruitment of muscle activity [Fryer 2006].
Practice settings
Muscle Energy Technique (MET) is used by all manual therapy professions in wide variety of practice settings. It can be applied with the patient seated, supine, side-lying, or prone, depending on which structures and tissues it is necessary to access. A number of self-help and home care protocols exist that allow individuals to be taught to safely and efficiently apply aspects of MET methodology. MET is therefore suitable for use in all clinical settings, as well as in the home for ongoing self-help use, or on a sports field for first aid.
Muscle Energy Technique (MET) offers no shortcuts to normal orthopedic and neurological assessment protocols. These need to be comprehensive, diligent, and thorough, in order to identify etiological as well as the maintaining features of any dysfunction. Once an accurate diagnosis is available, MET may be indicated, or an appropriate variation on the way MET is applied may be selected and used, either on its own, or in combination with other therapeutic modalities and methods.
Guidelines and protocols
Possibly the most critical element in preparing for an isometric contraction relates to the resistance barrier that is engaged. In treating restricted joints or muscles, the barrier is described as being at the ‘feather edge’ of resistance: the very first sign of resistance to free and easy motion, noted by the practitioner, as the structure is moved toward its normal end of range. End of range may at times be identified by patient feedback as the point in the movement arc, just short of where pain or discomfort is noted.
In order to produce an isometric contraction from the palpated, or reported barrier, the direction in which resisted movement is requested may be toward, or away from that barrier, or in a different direction altogether. Following a brief (three to seven second) very mild isometric contraction, and after complete relaxation, a restricted joint would be taken to its new barrier. A number of repetitions of the sequence are commonly employed, varying the direction of contraction each time.
When chronically shortened soft tissue structures are being treated with Muscle Energy Technique (MET), the barrier engaged should be well before the actual stretching of muscles commences. Following the contraction, the tissues are lightly stretched and held for between five and 30 seconds, depending on the bulk and degree of chronicity involved. One or two repetitions might be useful, with a new barrier identified each time. When acutely dysfunctional soft tissues are being treated (recent trauma or acutely painful), no stretching is introduced after the contraction, simply gentle movement of the tissues to a new resistance barrier, if this becomes available as hypertonicity reduces.
Most movements following an isometric contraction, whether to a new barrier, or through the old barrier into stretch, commence on an exhalation, apart from that involving quadratus lumborum which is stretched on an inhalation due to its physiological function as a 12th rib stabilizer during exhalation. Isometric contractions always involve the patient’s effort (muscle energy) in a defined direction and for a specified duration, starting and ceasing gradually, with the therapist providing resistance. Patients are requested to employ extremely mild degrees of force (less than 20% of available strength) for all isometric contractions.
Contractions in standard MET should last from three to seven seconds, depending on the bulk of the involved tissues, with a longer (approximately seven second) contraction appropriate for the hamstring group, for example, and three to four seconds for most joints or smaller muscle groups. When pulsed MET is used, a rhythmic series of isometric contractions is initiated, at a rate of one to two per second, for approximately ten seconds, commonly commencing with the efforts directed toward the resistance barrier. After this, the barrier is tested and the process repeated several times. These rhythmic pulsations should be extremely light, with no perceptible motion being permitted due to very firm resistance offered by the practitioner.
Basic techniques and methods
Before the use of Muscle Energy Technique (MET), the current range of motion (ROM) status of the joint or soft tissue should be established, both actively and passively, for comparison with post-MET ROM. The basic elements of MET involve identification of a painless resistance barrier, initiation of a controlled isometric contraction using minimal effort, in a precisely defined direction, and for a limited period, followed, after relaxation for a few seconds, of a movement toward a new barrier (joint or acute soft tissue problem) or into stretch for a chronic soft tissue problem.
Variations of technique or method
Apart from the obvious settings for MET as described above, a variation exists in which a shortened muscle is slowly stretched while it is being contracted, thus initiating an isotonic eccentric stretch. The effect is to lengthen that muscle (or reduce excessive tone) while simultaneously toning its antagonist(s). MET can be used during general soft tissue treatment, such as Neuromuscular Therapy (NMT)  or massage, wherever excess tone is identified, by having the patient introduce an isometric contraction, after which tissues should be less resistant to compression or stretch. Such an approach can form part of an integrated approach to trigger point deactivation, in which both local and whole muscle stretches follow isometric contractions [Chaitow 1994].
MET  variations for treatment of joint restrictions and soft tissue shortening/dysfunction, include :
There is  no stretching in acute conditions  (defined as a/acutely painful or b/recent – within 2-3 weeks of trauma c/inflamed  or  d/a joint)
  • Post-isometric Relaxation (PIR) – in both acute and  chronic variations,  describes an isometric contraction of the agonist(s) (i.e. the muscle(s) to be stretched or ‘released’) before stretching, or move to new barrier
  • Reciprocal Inhibition (RI) – describes contraction of antagonist(s) – to inhibit the agonist, before stretching, or move to new barrier
  • Pulsed  MET (Ruddy’s rapid resistive duction)  – uses minute repetitive contractions, usually of antagonist (facilitating the antagonist – inhibiting the agonist + possible circulatory and proprioceptive benefits)
  • Slow Eccentric Isotonic Stretching (SEIS) – involves slow resisted stretch of the antagonist of shortened structures, toning the antagonist isotonically, after which agonist is stretched.
  • Rapid Eccentric Isotonic Stretching (isolytic) can be used to break down or prevent adhesions (for example post-surgically) – and requires extreme care 
  • Isokinetic – multidirectional resisted active movements, designed to tone and balance muscles of injured joint
No pain should be produced during or after use of Muscle Energy Technique (MET). If an isometric contraction in one direction is more than mildly uncomfortable, then a different direction of effort should be employed, or a milder degree of force used. Clearly, if an individual is unable to generate a controlled contraction, MET is not appropriate, which makes its usefulness in infants, or anyone unable to respond appropriately to a contraction request, minimal. No attempt should be made to use MET to release protective spasm.
Bement M, Weyer A, Hartley S, Drewek B, Harkins A , Hunter S. 2011 Pain perception after isometric exercise in women with fibromyalgia. Arch Phys Med Rehabil. 92:89-95.
Chaitow L. Integrated neuromuscular inhibition technique in treatment of pain and trigger points. Br J Ost.1994;13:17-21.
Chaitow L. Muscle energy techniques. 3rd ed. Churchill Livingstone: Edinburgh, UK; 2006.Fryer G. MET technique: research and efficacy. In: Chaitow L (Ed). MET techniques. 3rd ed. Edinburgh, UK: Churchill Livingstone; 2006. Ch. 4. p.109-132.
Fryer G, Fossum C. 2009Therapeutic mechanisms underlying muscle energy approaches. In: Fernandez de las Penas C, Arendt-Nielsen L, Gerwin R (Eds). Physical therapy for tension type and cervicogenic headache: physical examination, muscle and joint management. Boston, MA, USA: Jones & Bartlett
Klingler W, Schleip R, Zorn A. 2004 European fascia research project report. Melbourne, Vic, Australia: 5th World Congress Low Back and Pelvic Pain
Lederman E. 1997 Fundamentals of manual therapy. London, UK: Churchill Livingstone; p34.
McPartland J. 2008 The endocannabinoid system: an osteopathic perspective. J Am Ost Assoc. 108(10):586-600.
Mitchell Sr. FL. 1948 The balanced pelvis and its relationship to reflexes. American Academy of Applied Osteopathy Yearbook p146-151
Nagrale AV, Glynn P, Joshi A , Ramteke G. 2010 The efficacy of an integrated neuromuscular inhibition technique on upper trapezius trigger points in subjects with non-specific neck pain: a randomized controlled trial. J Manual Manip Therapy. 18(1):38-44.
Parmar S et al 2011 Effect of isolytic contraction and passive manual stretching on pain and knee range of motion after hip surgery. Hong Kong Physiotherapy Journal 29:25-30
Ruddy TJ. Ruddy 1961 Osteopathic rhythmic resistive duction technique. Academy of Applied Osteopathy Yearbook; p 58-68.