PNF is using the force production of the muscle to create responses to allow the limb or joint to go past certain barriers by fooling the nervous system. MET is a type of PNF method. MET or Muscle Energy Techniques is using the force of the muscle to invoke a strain to later cause the joint to relax. Leon Chaitow uses this before he mobilizes joints with chiropractic adjustments. It is fast and great for spasm.