PNF is a stretching technique that combines passive stretching and isometric muscle contractions to improve flexibility and increase the range of motion on the specific muscle groups targeted.
How does it work?
Passive Stretch: The PNF stretching process typically begins with an initial passive stretch. This involves gently elongating the target muscle group to its limit without causing discomfort or pain. The stretch is held for a brief period (usually around 10-15 seconds).
Isometric Contraction: After the initial stretch, the individual being stretched, or their partner (such as a physical therapist or trainer) applies an isometric contraction to the same muscle group. During this phase, the individual actively contracts the muscle being stretched without allowing it to change length. This contraction is typically held for about 5-10 seconds.
There are 3 types of PNF Stretches:
Hold-Relax (HR): In this version, the individual contracts the muscle while maintaining the stretch position.
Contract-Relax (CR): In this version, the individual actively moves the limb or joint being stretched through its range of motion while contracting the muscle.
Hold-Relax with Agonist Contraction (HRAC): After the initial isometric contraction and relaxation, the individual contracts the opposing muscle group (agonist) while the partner assists with a passive stretch of the target muscle.
The effectiveness of PNF stretching lies in its ability to stimulate the Golgi tendon organs and muscle spindles, which are sensory receptors within muscles and tendons. These receptors help regulate muscle tension and provide feedback to the nervous system. The isometric contractions in PNF stretching temporarily override the stretch reflex, which can lead to a greater degree of muscle relaxation and increased flexibility.