"PNF stretching, or proprioceptive neuromuscular facilitation stretching, is a set of stretching techniques commonly used in clinical environments to enhance both active and passive range of motion with the ultimate goal being to optimize motor performance and rehabilitation.
The literature regarding PNF has made the technique the optimal stretching method when the aim is to increase range of motion, especially in short-term changes. Generally an active PNF stretch involves a shortening contraction of the opposing muscle to place the target muscle on stretch.
This is followed by an isometric contraction of the target muscle. PNF can be used to supplement daily stretching and is employed to make quick gains in range of motion to help athletes improve performance.
Aside from being safe and time efficient, the dramatic gains in range of motion seen in a short period of time may also promote compliance with the exercise and rehabilitation program."
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When we practiced PNF at the Physical Education class, we devided the method into three parts:
1.-Active or Passive Stretching of the target muscle. 10-15 seconds.
2.-Isometric contraction of the target muscle. 5-10 seconds.
3.-Active or Passive Stretching of the target muscle, increasing range of motion. 10-15 seconds.
Here you have a video where you can see both, active and passive options for your excercises: