Which type of stretching involves both stretching and contracting of the targeted muscle group?

The type of stretching that involves both stretching and contracting of the targeted muscle group is PNF, or Proprioceptive Neuromuscular Facilitation. This technique typically entails a series of stretching and contracting phases to improve flexibility and increase range of motion. In a typical PNF stretch, a muscle is first stretched to its limit, then the participant actively contracts the muscle against resistance for a few seconds, after which they relax and are able to stretch further due to the muscle’s temporary fatigue and relaxation response. This cycle of stretching and contracting takes advantage of the neuromuscular system's natural reflexes to enhance flexibility beyond what traditional static stretching might achieve alone.

Static stretching focuses solely on holding a position at the end of a muscle’s range without any active contraction involved, while dynamic stretching incorporates movement and is aimed at warming up the muscles through greater ranges of motion, but does not involve the contraction and relaxation principle inherent in PNF. Ballistic stretching involves bouncing movements to achieve a stretch and can be riskier as it may lead to injury if not done properly. In contrast, PNF is a more controlled and systematic approach to increasing flexibility.