Proprioceptive Neuromuscular Facilitation (PNF) is an advanced flexibility training method which enhances the flexibility of the joints by lengthening and strengthening the target muscle. Firstly the therapist takes the muscle to its ‘barrier’ – the maximum degree of stretch from the muscle. When this limit is attained the patient is required to perform a light contraction of the muscle which is resisted by the therapist. This engages the physiological phenomenon of post isometric relaxation thus allowing the therapist to gently lengthen the muscle until a new barrier is attained. By repeating this twice more the range of motion of the joint in gradually increased.