What is PNF stretching, and will it improve my flexibility?

Whether improving your flexibility was one of your new year’s resolutions, or you’ve been inspired watching certain tennis stars warming up at the Australian Open, maybe 2025 has you keen to focus on regular stretching.

However, a quick Google search might leave you overwhelmed by all the different stretching techniques. There’s static stretching and dynamic stretching, which can be regarded as the main types of stretching.

But there are also some other potentially lesser known types of stretching, such as PNF stretching. So if you’ve come across PNF stretching and it piques your interest, what do you need to know?

What is PNF stretching?

PNF stretching stands for proprioceptive neuromuscular facilitation. It was developed in the 1940s in the United States by neurologist Herman Kabat and physical therapists Margaret Knott and Dorothy Voss.

PNF stretching was initially designed to help patients with neurological conditions that affect the movement of muscles, such as polio and multiple sclerosis.

By the 1970s, its popularity had seen PNF stretching expand beyond the clinic and into the sporting arena where it was used by athletes and fitness enthusiasts during their warm-up and to improve their flexibility.

Although the specifics have evolved over time, PNF essentially combines static stretching (where a muscle is held in a lengthened position for a short period of time) with isometric muscle contractions (where the muscle produces force without changing length).

PNF stretching is typically performed with the help of a partner.

There are 2 main types

The two most common types of PNF stretching are the “contract-relax” and “contract-relax-agonist-contract” methods.

The contract-relax method involves putting a muscle into a stretched position, followed immediately by an isometric contraction of the same muscle. When the person stops contracting, the muscle is then moved into a deeper stretch before the process is repeated.

For example, to improve your hamstring flexibility, you could lie down and get a partner to lift your leg up just to the point where you begin to feel a stretch in the back of your thigh.

Once this sensation eases, attempt to push your leg back towards the ground as your partner resists the movement. After this, your partner should now be able to lift your leg up slightly higher than before until you feel the same stretching sensation.

This technique was based on the premise that the contracted muscle would fall “electrically silent” following the isometric contraction and therefore not offer its usual level of resistance to further stretching (called “autogenic inhibition”). The contract-relax method attempts to exploit this brief window to create a deeper stretch than would otherwise be possible without the prior muscle contraction.

The contract-relax-agonist-contract method is similar. But after the isometric contraction of the stretched muscle, you perform an additional contraction of the muscle group opposing the muscle being stretched (referred to as the “agonist” muscle), before the muscle is moved into a static stretch once more.

Again, if you’re trying to improve hamstring flexibility, immediately after trying to push your leg towards the ground you would attempt to lift it back towards the ceiling (this bit without partner resistance). You would do this by contracting the muscles on the front of the thigh (the quadriceps, the agonist muscle in this case).

Likewise, after this, your partner should be able to lift your leg up slightly higher than before.

The contract-relax-agonist-contract method is said to take advantage of a phenomenon known as “reciprocal inhibition.” This is where contracting the muscle group opposite that of the muscle being stretched leads to a short period of reduced activation of the stretched muscle, allowing the muscle to stretch further than normal.

What does the evidence say?

Research has shown PNF stretching is associated with improved flexibility.

While it has been suggested that both PNF methods improve flexibility via changes in nervous system function, research suggests they may simply improve our ability to tolerate stretching.

It’s worth noting most of the research on PNF stretching and flexibility has focused on healthy populations. This makes it difficult to provide evidence-based recommendations for people with clinical conditions.

And it may not be the most effective method if you’re looking to improve your flexibility in the long term. A 2018 review found static stretching was better for improving flexibility compared to PNF stretching. But other research has found it could offer greater immediate benefits for flexibility than static stretching.

At present, similar to other types of stretching, research linking PNF stretching to injury prevention and improved athletic performance is relatively inconclusive.

PNF stretching may actually lead to small temporary deficits in performance of strength, power, and speed-based activities if performed immediately beforehand. So it’s probably best done after exercise or as a part of a standalone flexibility session.

How much should you do?

It appears that a single contract-relax or contract-relax-agonist-contract repetition per muscle, performed twice per week, is enough to improve flexibility.

The contraction itself doesn’t need to be hard and forceful – only about 20% of your maximal effort should suffice. The contraction should be held for at least three seconds, while the static stretching component should be maintained until the stretching sensation eases.

So PNF stretching is potentially a more time-efficient way to improve flexibility, compared to, for example, static stretching. In a recent study we found four minutes of static stretching per muscle during a single session is optimal for an immediate improvement in flexibility.

Is PNF stretching the right choice for me?

Providing you have a partner who can help you, PNF stretching could be a good option. It might also provide a faster way to become more flexible for those who are time poor.

However, if you’re about to perform any activities that require strength, power, or speed, it may be wise to limit PNF stretching to afterwards to avoid any potential deficits in performance.