The instruction is given, ‘Now let your breath go and release your effort, slowly and completely’ - while you maintain the limb (in this example) at the same barrier.
The patient/model is asked to breathe in and out once more and to completely relax, and as they exhale you gently guide the limb to the point where you now sense a resistance barrier/bind.
You should almost always have created an increased range, by a significant degree.
After Post Isometric Relaxation (PIR) a refractory or latency period of anything from 15 to 30 seconds exists during which the muscle can be taken to its new resting length (where ‘bind’ begins) , or it can be tretched more easily than would have been the case before the contraction.3
What Alternative MET Methods are There?
You could repeat the exercise precisely as described above, working from the resistance barrier. This is Lewit’s PIR method and is ideal for releasing tone, for relaxing spasm, in acute conditions.4
Janda’s Approach for Chronic/Fibrotic Tissues5Where fibrosis is a feature of muscle shortening, as in many chronic conditions, a more vigorous contraction could be used involving actually stretch the muscle(s) rather than simply taking them to a new barrier. This calls for the starting of the contraction not from the point where bind is first noted, but from a more ‘slack’, mid-range, position.
Janda suggests stretching the tissues immediately following cessation of the contraction, and holding the stretch for at least 10 seconds, before allowing a rest period of up to half a minute and then repeating the procedure.
Modification of Janda’s approach:
A less stressful method suggests that following a contraction of anything up to 20 seconds, which starts in a mid-range position, uses between 20% and 50% of the patient’s available strength. A short (2 to 3 seconds) rest period is then allowed for complete relaxation, before stretch is introduced to a point just beyond the previous barrier of resistance. This is held for 10 seconds or so.
The procedure is repeated until no more gain is being achieved.
The Difference Between MET and Lewit’s PIR?
All elements of the procedures as described for PIR are maintained except -
- for chronic conditions the contractions starts short of the barrier
- contractions should be longer and stronger than in acute conditions, and
- the muscle(s) should be taken beyond rather than just to, the new barrier of resistance (with or without patient assistance) to begin to reduce shortening/contracture.
This procedure is much enhanced by using some patient participation during the stretching procedure - so that they help to take the limb/muscle(s) past the restriction barrier, so minimising the chances of a myotatic stretch reflex being triggered.6
Reciprocal Inhibition (R.I.)
A variation exists involving use of physiological mechanisms called reciprocal inhibition (RI) which also produces a neurologically induced a latency (‘refractory’) period of muscle relaxation.
- R.I. is advocated for acute problems, especially where the muscle(s) requiring release are traumatised, or painful and cannot safely be involved in sustained contractions.
- To use RI according you need to place the area in a ‘mid-range’ position, short of the resistance barrier because.7
- a/ It is easier to start a contraction from a mid-range position, and
- b/ there is a reduction in risk of cramp, particularly in lower extremity muscles such as the hamstrings.