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PNF stretching: The most effective way to improve active and passive range of motion

Pedro van GaalenAugust 17, 2023002k

Stretching is essential to ensure balance between muscle groups, improve flexibility and movement efficiency, improve biomechanical function and reduce injury risk, with proprioceptive neuromuscular facilitation (PNF) one of the most effective ways to achieve these goals.

We need to stretch for numerous reasons, most notably the need to keep the body in balance. The natural forces for everyday movement and exercise tend to shorten the muscles, which can restrict movement, reduce function and create biomechanical issues.

As such, stretching is essential to counteract these forces, keep the muscle or a muscle group’s elasticity, and reestablish muscle tone.

The stretch-relax mechanism

While there are a number of ways you can stretch a muscle, one of the most effective techniques to enhance both active and passive range of motion (ROM) is proprioceptive neuromuscular facilitation (PNF).

The science behind the effectiveness of PNF stretching and its biomechanical benefits is the reflex relaxation that occurs within the muscle and tendon structure (known as the musculotendinous unit) being stretched, which facilitates muscular inhibition.

This stretch-relax mechanism works because joints are controlled by two opposing sets of muscles, namely extensors and flexors, which must work in synchrony for efficient movement. Muscular inhibition happens when muscles on one side of a joint relax to accommodate the contraction of the muscle on the other side of that joint.

PNF stretching works by taking immediate advantage of the increased ROM that occurs during an isometric stretch, as the muscle performing the isometric contraction is relaxed and therefore retains its ability to stretch beyond its initial maximum length.

This allows us to train the stretch receptors to a greater degree than static or dynamic stretching, to get them used to this increased range of muscle length. The proposed mechanisms underlying the PNF stretching response, namely autogenic inhibition and reciprocal inhibition, are the generally accepted neurophysiological explanations for the superior ROM gains that PNF stretching delivers.

Know your terms:

Autogenic inhibition: A sudden relaxation of muscle after a high degree of tension is created in it. It is a self-induced, inhibitory, negative feedback lengthening reaction that protects against muscle tear. Golgi tendon organs are receptors for the reflex.
Reciprocal inhibition: The process whereby muscles on one side of a joint relax to accommodate a contraction on the other side of that joint. When a muscle spindle is stretched and the stretch reflex is activated, the opposing muscle group must be inhibited to prevent it from working against the resulting contraction of the homonymous muscle. This inhibition is accomplished by the actions of an inhibitory interneuron in the spinal cord.

Unpacking PNF techniques

PNF techniques combine passive and isometric stretching in three main types of stretches, which include passive (no associated muscular contraction), active (voluntary muscle contraction) and a ‘holding’ technique.

PNF techniques require a partner, or another mechanism that can facilitate a contraction and deeper stretch, to actively stretch the participant.

This isometric PNF stretching mechanism works by performing a stretch close to your maximum level of flexibility. That muscle is then flexed or isometrically contracted in that position for 10-20 seconds, and is then released. The initial stretch is then repeated, where you should be able to stretch further than you did before the contraction.

PNF can be used once or twice a week to supplement daily static and dynamic stretching routines. However, PNF stretching shouldn’t be done before another workout. It should be done in isolation, and only after a thorough warm up, which includes some light activity and some static stretching to improve peripheral blood flow and ‘loosen’ the muscles..

PNF stretching guidelines

Once you reach your near maximal stretch, hold the isometric contraction for at least 10-20 seconds.
Follow that with the relaxed stretch for at least another 20 seconds.
Perform 2-4 sets per stretching exercise.
Stretch once or twice a week.

Types of PNF stretching

Hold Relax: Place the muscle in a near maximal stretched position. Isometrically contract the muscle. Passively move the muscle into a stretched position that surpasses the previous near maximal point and hold.
Contract Relax: Passively place the restricted muscle into a position of stretch, then isometrically contract the muscle for a minimum of three seconds at a sub maximal effort (20-50% of max) to avoid muscle fatigue and injury. After the contraction relax the muscle and activate the opposing muscle to move the limb into a greater position of stretch.
Contract Relax Antagonist (Agonist) Contract (CRAC): Passively stretch the agonist muscle, then isometrically contract it maximally. Follow that with another passive stretch of the agonist muscle, followed by a maximal isotonic contraction of the antagonist muscle.
Slow reversals: An isotonic contraction of the agonist is followed by an immediate contraction of antagonist.

Basic PNF stretches

Seated Bicep Stretch: Sit on the floor or a bench and place your arms behind your hips. Get your trainer or partner to grab your wrists from behind, positioning them downward and close together, before raising your arms upward behind your body. Hold the stretch at near maximal for at least 20 seconds. Release the stretch and repeat 2-4 times.
Seated Front Delt Stretch: Sit on the floor or a bench and place your arms behind your hips. Get your trainer or partner to grab your wrists from behind, positioning them wider than shoulder-width apart, before raising your arms upward behind your body, and out to the sides. Hold the stretch at near maximal for at least 20 seconds. Release the stretch and repeat 2-4 times.
Overhead Tricep Stretch: Stand or sit on the floor or bench. Place your arm overhead. Get your trainer or partner to stand behind you, and grab your wrist, positioning your forearm against your upper arm. Your partner then pulls your elbow behind your head while keeping their forearm against your upper arm. Hold the stretch at near maximal for at least 20 seconds. Release the stretch and repeat 2-4 times. Repeat with the opposite arm.
Behind Head Chest Stretch: Sit on the floor or a bench. Place your hands behind your head, facing forward. Get your trainer or partner to stand behind you. They should position a leg behind your head, and place their hands on your elbows. They should then pull your elbows back. Hold the stretch at near maximal for at least 20 seconds. Release the stretch and repeat 2-4 times.
Lying Hamstring Stretch: Lie on the floor. Using a stretch band, rope or towel, extend your leg upward. Pull your leg as close to your chest as possible. Hold the stretch at near maximal for at least 20 seconds. Release the stretch and repeat 2-4 times. Repeat with the opposite leg.

Author: Pedro van Gaalen

When he’s not writing about sport or health and fitness, Pedro is probably out training for his next marathon or ultra-marathon. He’s worked as a fitness professional and as a marketing and comms expert. He now combines his passions in his role as managing editor at Fitness magazine.

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Pedro van Gaalen

When he's not writing about sport or health and fitness, Pedro is probably out training for his next marathon or ultra-marathon. He's worked as a fitness professional and as a marketing and comms expert. He now combines his passions in his role as managing editor at Fitness magazine.