Which of the following can help increase flexibility?

PNF techniques, or Proprioceptive Neuromuscular Facilitation techniques, are highly effective for increasing flexibility. This method incorporates both stretching and muscle contractions to enhance the range of motion around a joint. Typically performed in pairs, one person stretches a muscle while the other provides resistance. As the muscle is contracted, it can lead to greater stretching capability due to the reciprocal inhibition effect—where the contraction of one muscle leads to the relaxation of its opposing muscle.

Unlike other choices, which can have different primary objectives (such as building strength or power), PNF specifically targets flexibility improvements. This technique promotes increased muscle length through the combination of active and passive stretching, making it a favored approach among athletes and physical therapists aiming for broader and more efficient ranges of motion necessary for sports performance and injury prevention.

Static stretching also helps improve flexibility but achieves this through a different mechanism, focusing on holding a stretch to lengthen a muscle. While beneficial, it may not be as effective as PNF in terms of achieving significant flexibility gains in a single session. Plyometric exercises are designed for explosiveness and agility, while resistance training primarily focuses on building muscle strength, which does not directly enhance flexibility to the same extent as PNF techniques.