Muscle energy techniques in chiropractic practice
Lisi, Anthony J
Chiropractic Philosophy & Clinical Technique
Muscle energy technique (MET) is an umbrella term encompassing various types of active muscular relaxation and/or stretching procedures.1 Although the term MET has traditionally been associated with the osteopathic profession, many of these same procedures have also been referred to as manual resistance techniques by chiropractic authors.2 Indeed, an array of practitioners from the fields of osteopathy, chiropractic, medicine, physical therapy, and massage therapy have contributed to the evolution of MET.1
Two cornerstones of MET are reciprocal inhibition (RI) and post-isometric relaxation (PIR). RI, in theory, takes advantage of the neurologic phenomenon of muscular contraction, resulting in an inhibitory effect on antagonistic muscles (Sherrington’s law). For example, a contraction of the knee extensors will result in an inhibition or relaxation of the knee flexors. This is thought to be mediated by muscle spindle afferents.
The effect of PIR, on the other hand, is said to be mediated by afferent input from the Golgi tendon organs. When a muscle is held in an isometric contraction, the afferent feedback leads to inhibition of the given muscle, which is thought to result in relaxation of the muscle when the contraction is released.
Although MET procedures are commonly used in conjunction with chiropractic manipulative therapy (CMT),2,3 there is no consensus on a protocol of combining both therapies in a clinical encounter. Perhaps the most significant unknown is order. That is, when a doctor of chiropractic wishes to administer MET and CMT to the same region, which should be done first? Is it better to stretch tight muscles and then manipulate hypomobile joints, or should the joints be addressed before muscle stretching begins? There are two rules of thumb that have been proposed, each with its own shortcomings.
Most DCs seem to be in the “stretch-first, adjust-second” camp. Typically, their rationale is that loosening tight muscles in the region of joint restriction will result in a more comfortable, successful, and easily administered adjustment. The muscle stretching is considered a preparatory procedure for the primary intervention, the adjustment. Unfortunately, situations exist where joint hypomobility and/or pain can interfere with the performance of muscle stretching, as will be seen below. It also seems unwise to make treatment rules based primarily on the tradition of considering the adjustment more important than the stretching.
A growing contrasting opinion comes from the manual medicine field. Lewit and Janda have advocated manipulating joints first and stretching muscles second.2,4 This opinion is based on the muscular inhibition effect demonstrated by spinal manipulation. A number of studies have shown that manipulation results in a decrease in myoelectric activity.5-9 It is theorized, therefore, that stretching muscles after manipulation will result in a more successful stretch.
This approach may be particularly appealing since the original theoretical basis of MET-that various active contractions result in target muscle relaxation-has never been demonstrated. In fact, there is evidence that MET procedures actually result in increased myoelectric activity of the target muscle.10-12 Thus, it has been suggested that the clinical benefit derived from MET stretching may be due to patients feeling more involved and/or confident in the procedure, and willing to tolerate the discomfort of the stretch, rather than any neurologic muscular relaxation. So if manipulation could provide the muscular inhibition that MET does not, it would be reasonable to capitalize on that inhibition.
One problem with the manipulate– first, stretch-second opinion as a rule, however, is that some studies have shown manipulation can also result in increased myoelectric activity.13-15 In this light, it might be argued that manipulation should not even be performed in the same treatment session as stretching– quite apart from the question of sequence. Our knowledge of the muscular effects of manipulation, however, is still in its infancy. It seems premature to make any rules regarding the clinical combination of manipulation and stretching without more substantial evidence.
Nevertheless, the clinician must still make a decision to determine order of application. Since tradition and neurologic responses are not yet validated, one suggestion is to rely on reproduction of patient symptoms, rather than on a predetermined rule.
Consider a given patient with a complaint of neck pain who exhibits the following findings: decreased cervical left lateral flexion; hypertonic and tender right scalene muscles; and hypomobile and tender left C4-5 and C5-6 facet joints. Along with the entire clinical picture, these findings may lead a clinician to wish to stretch the muscles and adjust the joints.
In situation A, assume passive left lateral flexion in the above patient is met with significant pain in the right scalene muscles (Fig. 1, A). This may compromise the positioning for a given adjustive maneuver say a supine modified rotary break on the left (Fig. 2) – due to patient apprehension or doctor inability to employ appropriate lateral flexion. In this case, it seems to follow that stretching the muscles before the adjustment would be appropriate. Positioning for the stretch could be started at patient tolerance, and increasing the pain-free range could subsequently allow for the delivery of the adjustment.
In situation B, same patient, assume passive left lateral flexion is met with significant pain in the region of the left facet joints (Fig. 1, B). Here, performance of a right scalene stretch (Fig. 3) may be compromised by the left-sided pain, but manipulation of the involved joints, with either a shearing or gapping maneuver (i.e., left- or right-sided contact, respectively), could be well tolerated. In this case, the adjustment may be a necessary precursor to effective stretching.
The concept of pain response guiding treatment decisions may seem entirely pedestrian to many doctors of chiropractic; however, it has been demonstrated to be a valuable principle.15-20 Yet, admittedly, in many patients a clear pain response may not exist, in which cases theory and opinion are all that one can rely on to determine treatment order. Indeed, in these cases, the order may not have any bearing on clinical outcome. When order can be inferred from a particular pain response, however, it seems reasonable to follow that order. Until outcomes evidence exists, minimizing patients’ pain in the real time of a clinical encounter may be the best guiding principle available.
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13. Dishman JD, Ball KA, Burke J. Central motor excitability changes after spinal manipulation: A transcranial magnetic stimulation study. J Manipul Physiol Ther. 2002;25:1-9.
Dr. Lisi is an assistant lecturer in the departments of technique and research at Palmer College of Chiropractic West. Address correspondence to: firstname.lastname@example.org.
This column is coordinated by Dr. Robert Cooperstein at Palmer College of Chiropractic West. Submissions for this column may be sent to email@example.com.
Copyright American Chiropractic Association Oct 2002
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