Proprioceptive Neuromuscular Facilitation or PNF stretching involves a component of stretch - muscle contraction - and further stretch. This process is usually repeated several times and uses a trick on the muscle spindle reflex to help elongate your muscles
The technique of PNF stretching was first developed as a muscle therapy but is now used by athletes as a means of enhancing flexibility. PNF stretching is often used by massage therapists, physiotherapists, physical therapists, chiropractors and physiatrists (rehabilitation medical doctors). More information can be sought by seeking their advice in your situation.