While there are multiple PNF stretching techniques, all of them rely on stretching a muscle to its limit. Doing this triggers the inverse myotatic reflex, a protective reflex that calms the muscle to prevent injury
One PNF technique that Black says can trigger the reflex is commonly called “hold-relax.” This involves:
- Putting a muscle in a stretched position (also called a passive stretch) and holding for a few seconds.
- Contracting the muscle without moving (also called isometric), such as pushing gently against the stretch without actually moving. This is when the reflex is triggered and there is a “6- to 10-second window of opportunity for a beyond ‘normal’ stretch,” Black says.
- Relaxing the stretch, and then stretching again while exhaling. This second stretch should be deeper than the first.
Another common PNF technique is the contract-relax stretchTrusted Source. It is almost identical to hold-relax, except that instead of contracting the muscle without moving, the muscle is contracted while moving. This is sometimes called isotonic stretching.
For example, in a hamstring stretch, this could mean a trainer provides resistance as an athlete contracts the muscle and pushes the leg down to the floor.
A third technique, hold-relax-contractTrusted Source, is similar to hold-relax, except that after pushing against the stretch, instead of relaxing into a passive stretch, the athlete actively pushes into the stretch.
For example, in a hamstring stretch, this could mean engaging the muscles to raise the leg further, as the trainer pushes in the same direction.
Regardless of technique, PNF stretching can be used on most muscles in the body, according to Black. Stretches can also be modified so you can do them alone or with a partner.