Which is most associated with proprioceptive neuromuscular facilitation?

While breathing can complement stretching, PNF is defined by its neuromuscular contraction-relaxation cycle, not breathing techniques.

PNF is primarily a stretching technique that uses alternating contraction and relaxation of muscles to take advantage of autogenic and reciprocal inhibition reflexes, thereby increasing flexibility beyond what static stretching alone achieves. Common PNF methods include hold-relax and contract-relax protocols that involve a partner or fixed object. It is widely recognized in exercise science literature as the most effective flexibility modality.

PNF involves brief muscle contractions as part of the stretch protocol, but its primary classification and purpose is flexibility and stretching, not resistance training for strength or hypertrophy.

PNF has no defining association with cardiovascular exercise; it is a neuromuscular stretching methodology focused on range of motion.