Stretching is an integral part of any workout routine. Greater flexibility enables us to become more resistant to injury while gaining strength, but most people only know about two types of stretches:
- Static: Traditional stretching where a muscle is held in an elongated position for up to 30 seconds (think toe-touches) to release tension and make muscles more pliable.
- Dynamic: Movement-based activities (e.g., trunk twists, high knees) to prime the body for action.
But there’s another way to increase flexibility and range of motion called PNF stretching. If you’ve ever worked out with a personal trainer who stretched you post-workout or visited one of the trendy stretching studios, you may already be familiar with this practice.
Whether you are a novice or frequently have someone else stretch you, here’s what you need to know about PNF stretching.
What Is PNF Stretching?
Proprioceptive neuromuscular facilitation, or PNF stretching, involves stretching a muscle to its limit and then contracting that muscle or a surrounding muscle to allow for a deeper stretch — similar to active stretching. The goal of the practice is to unlock greater ranges of motion and improve flexibility.
Physical therapists developed PNF in the 1940s as a way to treat patients with polio and multiple sclerosis and later began using it for other conditions. “PNF stretching is primarily used in rehabilitative and orthopedic settings to restore flexibility, strength, and coordination to injured muscles,” explains Chris Gagliardi, scientific education content manager for the American Council on Exercise. Most often, this stretching is done with a trained partner.
However, anyone who wants to improve mobility can benefit from PNF techniques. “It’s a treatment method and philosophy that utilizes the power of the nervous system to enhance movement,” says personal trainer and physical therapist Keats Snideman, PT, DPT, COMT, CSCS, LMT.
He explains that breaking down the acronym helps to understand how it works:
- Proprioceptive: Referring to the many sensory receptors that relay information about the movement and position of the body back to the central nervous system.
- Neuromuscular: The connection between the nerves and the muscles/tendons that they supply.
- Facilitation: To make an action or process easier.
How Does PNF Stretching Work?
Snideman splits PNF concepts into “direct” and “indirect” techniques. Direct methods use force provided by the muscle being stretched, while indirect methods use force provided by muscles that oppose the one being stretched.
Direct techniques
Direct techniques are used for tight muscles that aren’t painful or dangerous to stretch. A common stretching method is contract-relax (CR):
- You stretch the tight muscle to its end range of motion or just shy of it if that’s painful.
- Then from that position, isometrically contract the muscle (a.k.a. push against a force without moving the muscle) for five to 10 seconds.
- After a brief relaxation, you’ll find that you can stretch the muscle a bit deeper.
For example, if you were to stretch your hamstring, you’d lie on your back and lift your leg up as high as it can go while keeping it straight. Then, push against an opposing force — like a partner, strap, or wall — as if you were going to lower your leg back down, but make sure your leg doesn’t move. After contracting for up to 10 seconds, relax your leg, and you should be able to lift it higher than you did previously.
“This technique works by what is called ‘post-isometric relaxation,’” Snideman explains, “which means that a muscle has a brief period of relaxation after isometric contraction.”
This relaxation is possible because of a reflex called autogenic inhibition. When the muscle contracts, sensory receptors called golgi tendon organs send an inhibitory signal that directs the muscle to release tension, allowing it to elongate. Put simply, the muscle relaxes itself when it experiences too much tension.
You can often do direct PNF stretching with a partner or with props like a strap or a wall.
Indirect techniques
Indirect techniques use antagonist, or opposing, body parts to stretch a tight muscle. “This technique might be better when a muscle is weak or painful to contract,” Snideman says.
With indirect techniques:
- You stretch the tight muscle to its end range of motion or just shy of it if that’s painful.
- Then, rather than contracting that muscle, you isometrically contract other opposing muscles for five to 10 seconds, which, in turn, help the tight muscle relax and stretch.
For example, if you were to stretch your chest, you’d lift your arm up so that it’s parallel to the ground and stretch it as far back behind as you can without pain. From that point, brace your arm against a partner or a wall behind you and contract the muscles in your shoulders and upper back to push against the force. After contracting for up to 10 seconds, relax your arm, and you may find more range of motion in the initial chest stretch.
During this technique, the muscles engage in reciprocal inhibition. While one muscle is contracting, inhibitory signals cause the opposing muscle to relax.
Indirect PNF stretching is typically performed with a partner, but it may be possible to stretch on your own with props, depending on what muscle you’re targeting.
When Should I Do PNF Stretching?
“There is no consensus on when it is best to use PNF stretching,” Snideman says. “But if this type of stretching is used prior to activity, it can help someone achieve the range of motion they need for whatever activity they are about to partake in.”
It’s best to warm up before doing PNF stretching, as flexibility is most effectively trained when the muscle is warm, Gagliardi adds.
Also, before exercise, be sure to do some dynamic stretching after PNF stretching. Otherwise, studies show you may have less vertical jump height or power during your workout.
What Are the Benefits of PNF Stretching?
“PNF-type stretching often produces a greater increase in range of motion more quickly than passive or static approaches,” Snideman says.
In a study published in Biology of Sport in 2016, researchers divided 40 college students with tight hamstrings into four groups. Three days a week for four weeks, students performed:
- Typical static stretching
- PNF stretching
- Mulligan traction straight leg raise (TSLR) technique (another technique that increases hamstring flexibility)
- No stretching
PNF stretching and Mulligan TSLR both increased hamstring range of motion more than static stretching did. Some even consider PNF the “most effective stretching technique” for increasing range of motion.
Precautions When Practicing PNF Stretching
To be safe, only do PNF stretching with a professional, such as a personal trainer or physical therapist trained in the practice. Tell them about any injuries or strains, as contracting injured muscles or tendons may worsen things, Snideman cautions.
This also applies if you’ve had recent surgeries, as stretching the affected muscles may impair recovery. Once you know the techniques, you may be able to do some PNF stretching on your own.
