How to PNF Stretch

The Theory of PNF

First a brief description of stretches.

Isotonic Contraction: A voluntary contraction that causes movement to occur. This can be broken down into Concentric Contraction (in which the muscle shortens during contraction) and Eccentric Contraction (where the muscle is lengthened during contraction).

Isometric Contraction: is a voluntary contraction in which no movement occurs.

The Stretch Reflex

The stretch reflex is initiated as a response to stretch to help protect muscles and joints from injury due to overstretching or excessive strain.

The Myotatic Stretch Reflex prevents the muscle from stretching too far, too fast. Proprioceptors called “muscle spindle cells” monitoring the length and tension of the muscles reflexively cause the muscle to contract when it lengthens too quickly.

The Inverse Stretch Reflex (Autogenic Inhibition) gives the opposite effect to the Myotatic Stretch Reflex. When this stretch reflex occurs the muscle relaxes. The Inverse Stretch Reflex is mediated by receptors called Golgi mTendon Organs located in the musculotendinous junction and the tendon. The Golgi Tendon Organs monitor the load on the tendons. When the load becomes too great the GTOs are stimulated they cause the muscle to relax through neurological inhibition.

Tendon loading can be from a strong contraction or a stretch, especially an isometric contraction. When a muscle stretch is held the pull on the tendon stimulates the GTOs and causes the muscle to relax and lengthen. This reduces the chance of muscle tearing.

Proprioceptive Neuromuscular Facilitation Stretching

The methods we will be discussing are Facilitated Stretching (where the patient moves their muscles into stretch) and Hold and Relax Stretching (where you will move the patient's muscles passively).

As the level of feel and experience varies between therapists the choice of stretching will be left up to you. Facilitated stretching is less likely to cause muscle fibre tears as the patient is moving the muscle into the next pain free zone themselves. If unsure of the stretch GET THE PATIENT TO MOVE THEMSELVES.

It uses the following 3 stages:

CONTRACT: the muscle/muscle group is contracted against resistance using around 10 % of full strength without shortening of the muscle group (i.e. isometric contraction) for 10 seconds.

RELAX: the muscle/muscle group is allowed to relax for 5 seconds while taking a large breath in and out.

STRETCH: the muscle/muscle group is gently stretched as far as possible without excessive discomfort and held for 10 seconds. (this is the point where the patient can move the muscles themselves).

The whole process is performed 3 times for each muscle/muscle group.

The stretch will begin at what is called the Pathological Motion Barrier. This is the point where the therapist will first feel a resistance to stretch. We will refer to this as R1 (the first sign of stretch).

At this point the patient will be asked to contract the muscle with around 10% of their full strength for 10 seconds. At the end of the stretch do not ease off or apply pressure. Ask the patient to take a deep breath in and out and to relax the muscle.

On reaching the final position the stretch can be held for up to two minutes if pain free.

To protect the patient we use the following protocol:

R1 = first sign of resistance.

The first sign of stretch felt by the therapist.

S1 = first sign of stretch.

The first sign of stretch as felt and communicated by the patient.

P1 = first sign of pain.

The first sign of pain as felt and communicated by the patient.

Do not take the stretch beyond R1, S1 or P1.