Contract-Relax stretching, sometimes referred to as PNF or MET, involves an initial onset of stretch at a particular range of movement for a muscle, contracting the muscle statically (without movement) towards shortening for 4-6 seconds. Once that static contraction ceases, the stretch is taken further into the new onset of stretch. We normally do this three times and it's a very fast way to increase rom and muscle length.
The three terms for Contract-Relax stretching are used interchangeably as different modalities have adopted each other's names for similar techniques, although they do vary in application slightly.
PNF (Proprioceptive Neuromuscular Facilitation) stretching is a form of contract-relax stretching which is traditionally used by Physiotherapists. Originally all PNF stretches involved three planes of movement and a wind up and stretch which targets nerve stretching. The contract relax phase is usually around 4-6 seconds of isometric contraction starting from a stretched position. When the patient relaxes the nerve is taken into a further stretch. This is normally done in sequences of three and we always end in relax with further stretching.
MET (Muscle Energy Technique) is also a form of contract-relax stretching, which was originally an osteopathic technique. It was designed for spinal segments as a safer and more gentle way to increase mobility of spinal joints compared to "cracking" or HVLA manoeuvres. With MET, traditionally a practitioner would couple two movements, for example lateral flexion and rotation, and take the joint into some resistance. The practitioner would then commence an isometric contraction against resistance from the practitioner for 4-6 seconds. The practitioner would then take the joint into an increased range of motion as the patient relaxes.
Standard Contract-Relax stretching is the same sequence with a series of joints being taken into a position of stretch. The muscle that is being stretched is then contracted with the practitioner resisting at a very light pressure of around 20% of max for around 4-6 seconds. After that, as the patient relaxes, the practitioner increases the stretch.
All three forms of contract-relax stretching are taking advantage of what is called a post-isometric relaxation phase where a Golgi tendon organ located in the muscle tendon junction, which regulates stretch, is basically being tricked and as you relax from a position of stretch and isometric contraction, the Golgi tendon organ allows more movement allows more movement than it normally would as it is momentarily unaware of the amount of stretch that it is under.
The Soft Tissue Therapists at NSTT will often use MET, PNF or Contract-Relax stretches to help increase flexibility and increase function and to loosen tight muscles.