Muscle Energy Technique known as MET is one of the manual therapy techniques.
This technique uses a muscle’s own energy by performing isometric contractions to relax the muscle through autogenic or reciprocal inhibition, and lengthen the muscle. General stretch which is called static stretch is performed without muscle contraction.
MET consists of mainly two techniques which are autogenic inhibition and reciprocal inhibition.
These autogenic and reciprocal inhibition happen when certain muscles are inhibited from contracting due to Golgi Tendon Organ (GTO) and muscle spindle.
These two muscle receptors locate in and around the joints and muscle to control muscle length, tension and coordination whereas GTO is in muscle belly and its tendon.
Autogenic inhibition
When the muscle contracts, the GTO is activated and responds by inhibiting the contraction (relax inhibition) and contracting the antagonist muscle group.
The GTO works as a role of flexibility. When the GTO inhibits the agonist muscle’s contraction and allows antagonist muscle to contract more. The muscle can be stretched further and easier. This is often seen and happens in static stretch, muscle tension increases after 7-10 secs, muscle tension activates GTO response which causes the agonist muscle to be inhibited temporarily and make it to stretch the muscle further.
Reciprocal Inhibition
The muscle spindle locates in the muscle belly and works as a stretching along with the muscle. When this happens, the muscle spindle is switched on and causes a contraction in the agonist muscle which is known as the stretch reflex or reflexive contraction, and relax the antagonist muscle.
Basically, autogenic inhibition which gets GTO to work focuses on agonist muscle to contract and in order to stretch further to avoid over-contracting while reciprocal inhibition aims agonist muscle so that antagonist can stretch further.
Ex.) A patient has a tight hamstrings and SLR test (Straight Leg Raise) shows that he has the restricted range which is 45 degrees.
If utilize autogenic inhibition (Post isometric relaxation),
Lie down on the back, bring a leg to 45 degrees and get him to push down against the therapist force followed by 5-10 secs stretch. Target muscle should be contracted.
If perform reciprocal inhibition (reciprocal inhibition MET),
Lie down on the back, bring the leg to 45 degrees and get him to push towards his body against the therapist’s force for 10 secs followed by 5-10 secs stretch. The opposite of target muscle should be contracted.
| Receptor | Target | Force | Time | Trigger | Reflex | Location | Inhibition |
| GTO | Agonist muscle | Over 50% | Over 6secs | Tension | Autogenic inhibition | tendon | Agonist |
| Muscle spindle | Antagonist muscle | 20% | 5-10 secs | Lengthen | Reciprocal inhibition | Muscle belly | Antagonist (not stretch reflex) |
PNF (Proprioceptive Neuromuscular Facilitation)
PNF uses also autogenic inhibition. The biggest difference is that PNF utilises the reflex from GTO and muscle spindles. The procedure (this can vary) starts with 30 seconds of static stretch (or passive stretch) followed by 10 secs of isometric or concentric-isometric contraction. Then perform 30 secs of static stretch (passive stretch). In the first 30 secs of stretch, GTM gets activated to tell the brain that the muscle needs to contract to avoid overstretching. Then in 10 secs of the isometric contraction, muscle spindles go” the muscle needs to relax” which is completely opposite information and bewildering the brain. When you perform second passive stretch, muscle spindle sends information saying the muscle you are stretching needs to relax or stretch. Therefore, you get huge improvement on the ROM.
Reference
Physiopedia Muscle Energy technique https://www.physio-pedia.com/Muscle_Energy_Technique
