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.

Lewis Ingram, Lecturer in Physiotherapy, University of South Australia and Hunter Bennett, Lecturer in Exercise Science, University of South Australia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Mulch containing asbestos has now been found at 41 locations in New South Wales, including Sydney parks, schools, hospitals, a supermarket and at least one regional site. Tests are under way at other sites.

As a precautionary measure, some parks have been cordoned off and some schools have closed temporarily. Fair Day – a large public event that traditionally marks the start of Mardi Gras – was cancelled after contaminated mulch was found at the site.

The New South Wales government has announced a new taskforce to help investigate how the asbestos ended up in the mulch.

Here’s what we know about the risk to public health of mulch contaminated with asbestos, including “friable” asbestos, which has been found in one site (Harmony Park in Surry Hills).

What are the health risks of asbestos?

Asbestos is a naturally occurring, heat-resistant fibre that was widely used in building materials from the 1940s to the 1980s. It can be found in either a bonded or friable form.

Bonded asbestos means the fibres are bound in a cement matrix. Asbestos sheeting that was used for walls, fences, roofs and eaves are examples of bonded asbestos. The fibres don’t escape this matrix unless the product is severely damaged or worn.

A lot of asbestos fragments from broken asbestos products are still considered bonded as the fibres are not released as they lay on the ground.

Friable asbestos, in contrast, can be easily crumbled by touch. It will include raw asbestos fibres and previously bonded products that have worn to the point that they crumble easily.

The risk of disease from asbestos exposure is due to the inhalation of fibres. It doesn’t matter if those fibres are from friable or bonded sources.

However, fibres can more easily become airborne, and therefore inhalable, if the asbestos is friable. This means there is more of a risk of exposure if you are disturbing friable asbestos than if you disturb fragments of bonded asbestos.

Who is most at risk from asbestos exposure?

The most important factor for disease risk is exposure – you actually have to inhale fibres to be at risk of disease.

Just being in the vicinity of asbestos, or material containing asbestos, does not put you at risk of asbestos-related disease.

For those who accessed the contaminated areas, the level of exposure will depend on disturbing the asbestos and how many fibres become airborne due to that disturbance.

However, if you have been exposed to, and inhaled, asbestos fibres it does not mean you will get an asbestos-related disease. Exposure levels from the sites across Sydney will be low and the chance of disease is highly unlikely.

The evidence for disease risk from ingestion remains highly uncertain, although you are not likely to ingest sufficient fibres from the air, or even the hand to mouth activities that may occur with playing in contaminated mulch, for this to be a concern.

The risk of disease from exposure depends on the intensity, frequency and duration of that exposure. That is, the more you are exposed to asbestos, the greater the risk of disease.

Most asbestos-related disease has occurred in people who work with raw asbestos (for example, asbestos miners) or asbestos-containing products (such as building tradespeople). This has been a tragedy and fortunately asbestos is now banned.

There have been cases of asbestos-related disease, most notably mesothelioma – a cancer of the lining of the lung (mostly) or peritoneum – from non-occupational exposures. This has included people who have undertaken DIY home renovations and may have only had short-term exposures. The level of exposure in these cases is not known and it is also impossible to determine if those activities have been the only exposure.

There is no known safe level of exposure – but this does not mean that one fibre will kill. Asbestos needs to be treated with caution.

As far as we are aware, there have been no cases of mesothelioma, or other asbestos-related disease, that have been caused by exposure from contaminated soils or mulch.

Has asbestos been found in mulch before?

Asbestos contamination of mulch is, unfortunately, not new. Environmental and health agencies have dealt with these situations in the past. All jurisdictions have strict regulations about removing asbestos products from the green waste stream but, as is happening in Sydney now, this does not always happen.

What if I’ve been near contaminated mulch?

Exposure from mulch contamination is generally much lower than from current renovation or construction activities and will be many orders of magnitude lower than past occupational exposures.

Unlike activities such as demolition, construction and mining, the generation of airborne fibres from asbestos fragments in mulch will be very low. The asbestos contamination will be sparsely spread throughout the mulch and it is unlikely there will be sufficient disturbance to generate large quantities of airborne fibres.

Despite the low chance of exposure, if you’re near contaminated mulch, do not disturb it.

If, by chance, you have had an exposure, or think you have had an exposure, it’s highly unlikely you will develop an asbestos-related disease in the future. If you’re worried, the Asbestos Safety and Eradication Agency is a good source of information.

Peter Franklin, Associate Professor and Director, Occupational Respiratory Epidemiology, The University of Western Australia

This article is republished from The Conversation under a Creative Commons license. Read the original article.