We all have our ‘box’ of skills, I believe what is so wonderful about bodywork is that each therapist connects with different skills, and applies them in their own unique way; however the science behind it is the same.
One of my most useful tools is Muscle Energy Technique, so I thought I would use these pages as a beneficial review. Whilst there is lots of debate in literature about how MET works. Some focus on the Golgi tendon organs, whereas some authors focus on the muscle spindle. It is best to have a clear understanding of the essential neurologic role of the muscle spindle MET works the conscious, voluntary contraction of isolated muscles. Creating an isolated voluntary contraction is different from the muscle contraction we use in everyday life. Because the higher brain centres are used to isolate muscle contraction, this is a unique neurologic effect, compared to those accomplished in everyday functional activities.
- Extrafusal fibres, these provide the force of muscle contraction and are innovated by alpha motor nerves.
- Intrafusal fibres, also called muscle spindles. These are activated by the gamma nerves, which act as sensory receptors to help control the tone and length of the muscle.
– If a muscle contraction is sustained over a length of time, this can either be unconsciously or involuntary tightened. It is thought that the gamma motor neuron activity has set itself an abnormally high firing rate. This then keeps the muscles tone too high (hypertonic), so when it is resting, it is too short.
– Voluntary isometric contraction makes the fibres at the belly of the muscle shorten, loosening the intramural fibres and unloading the muscle spindle, switching it off temporarily. As isolated voluntary isometric contraction requires only alpha motor nerve activity, the gamma motor nerve is not firing to the muscle spindle.
– When muscles relax after voluntary isometric contraction, the alpha motor nerve switches off and the belly of the muscle lengthens. As this relaxation takes place, the gamma motor nerve switches on to re-set the muscles resting tone. In theory, because gamma motor nerves have just been turned off, the new rate at which they are firing has been reduced, decreasing the resting tone of the muscle.
Mechanical Basis of Muscle Relaxation Using MET
Muscles that are in an adaptive, shortened position or held in a sustained contraction have an increased stiffness. Relaxation after isometric contraction increases muscle temperature and reduces this stiffness because of the thixotropic (solidifies when cold or still / more fluid when warmed or stirred) property of the muscle.
How Muscle Energy Technique can lengthen muscle and reduce trigger points.
- Muscle contraction increases muscle temperature because the stored energy from the contraction is released as heat, as the muscle relaxes. The heat increases the elasticity and extensibility of the connective tissue (the fascia of the muscle tendon unit) and decreases the viscosity within the muscle.
- When a muscle contracts isometrically, the muscle fibres shorten and the connective tissue lengthens to keep the muscle at the same length. This lengthening dissolves abnormal crosslinks in the collagen, allowing more normal gliding of the fibres and permitting the muscles to be stretched to a new length.
- The muscle spindles are allowed to be set to a new length-tension relation after an isometric contraction.
- The pain and dysfunction associated with trigger points is relieved when the muscle is restored to its full length.
Therapeutic Principles of Muscle Energy Technique.
There are many styles of MET. The style listed below has proved most effective clinically.
- One of the most important things to remember with the MET is that it should never be painful. Should it be even mildly painful, STOP. Less pressure should then be used until a comfortable resistance is found.
- If it is still painful, use RI (reciprocal inhibition). If you find the contraction still elicits pain, work with any muscle related to the associated joint that is not too painful.
- Perform MET on the hypertonic or shortened muscles first, as those tissues inhibit their antagonists. After you have released the hypertonic muscles use MET to strengthen the weaker ones.
- Take the muscle to its mid-range position half way between its fully stretched and fully relaxed position. In this position it is the most accurate measure of its strength, and is usually the most comfortable. If a muscle cannot be placed in its midrange position, it is placed at its pain or resistance barrier.
- It is important that the therapist communicates clearly with the patient as to how much pressure they exert; otherwise some patients believe their strongest effort is required, which could cause them to strain themselves, or even overwhelm the therapist.
- The therapist typically applies only a modest pressure that requires only 10-20% of their strength to resist the therapist’s force. In acute conditions, it only takes a few grams of pressure to create a neurological change. In chronic conditions you may have to use up to 50% resistance to create the heat in the muscle to gain any sensory awareness to that area which has been unconsciously hypertonic.
- This contract-relaxation cycle is typically repeated 3-5 times; however it may be repeated as many times as 20 in chronic conditions.
- It is often helpful to add a contraction to the opposite muscle (antagonist) after the contraction of the agonist. This is especially helpful after the PIR (Post Isometric Relaxation), as it not only adds a deeper level of relaxation, but also “sets” the involved muscle in a relaxed state in its lengthened position. This is accomplished through reciprocal inhibition.
The basic therapeutic intentions of METs for acute conditions:
- Reduce muscle spasm.
- To create a gentle pumping action to reduce pain, swelling, encourage oxygenation of the tissue, enabling removal of any waste product.
- Offer neurological contribution, to lessen muscular inhibition.
- To help sustain as much pain free joint motion as possible.
The basic therapeutic intentions of Mets for chronic conditions.
- Reduce muscle spasm.
- Strengthen muscles, lengthen muscles.
- Increase ROM of joints and increase in lubrication.
- Restores neurological function.
- Decreases excessive muscle tension.