What it is
Simply put: “PNF” stands for Proprioceptive Neuromuscular Facilitation, and is implemented as a way to utilize the neuromuscular system to bring about a relaxation response in targeted muscle groups. It’s a much more efficient form of stretching, as it allows for going deeper into a stretch than you could typically achieve with 20-60 seconds of a simple passive stretch. In fact, PNF stretching has been found to increase flexibility of your targeted muscles, and increase the range of motion of the related joints.
The increased stretch response is thought to arise from a combination of autogenic inhibition (decreased excitability of the muscle fibers due to inhibitory signals), reciprocal inhibition (which occurs in the targeted muscle when the opposing muscle is contracted), stress relaxation (the muscle tendon unit gradually elongates as a stretch is held for time), and gate control theory (when pain and pressure are sensed simultaneously, the sensation of pressure overwhelms the sensation of pain, causing the Golgi tendon organ sensors to decrease their inhibition of muscle lengthening).
How to apply it
PNF stretching involves alternating strong contraction of the muscle being targeted for stretching, followed by relaxing deeply into the stretch. When performed prior to strength exercise, PNF and static stretches have been found to have a temporary effect of decreasing performance of strength training, sprinting, plyometrics, and other high intensity exercises. For that reason, active range of motion is considered a better warm-up than static or PNF stretching prior to exercise. However, when performed after exercise, static and PNF stretching have beneficial effects, such as enhancing performance, decreasing risk of injury, and improving range of motion and function following an injury.
A common protocol is to apply a near maximal contraction for six seconds, followed by relaxation into the stretch for ten seconds — repeating the sequence for four total sets.
For example, to stretch the hamstring muscle group, one can lie supine and reach one leg up toward the ceiling. A partner can hold the back of the heel to provide isometric resistance. Keeping the knee straight and the pelvis stable, press the heel into the resistance of the partner’s hand for six seconds. Apply near maximal force; be sure to continue breathing. Then relax into the stretch for ten seconds, while the partner applies gentle pressure to assist further stretching of the hamstring muscles. Repeat three more times.
If you do not have a partner available to assist, you can do the same thing with a stretching strap. Holding the ends of the strap, and with the strap around the bottom of the foot, press your heel downwards against the resistance of the strap for six seconds, and then pull the ends of the strap for ten seconds while relaxing deeper into the stretch.
This approach could be applied to stretching almost any muscle group. For another example, while doing a standing quadriceps stretch, you can press the top of your foot into your hand for six seconds, and then pull the foot higher into the stretch for ten seconds. Again, repeat three more times.
PNF stretching can be added to your post-exercise routine on occasion to help loosen up particularly tight muscles. As a regular daily practice, active range of motion warm-up movements, foam rolling before and/or after exercise, and passive stretching post-exercise will help you be more mobile, with reduced risk of chronic pain and overuse injuries
Something to note: It is important to listen to your body to avoid overstretching. A slight discomfort in the stretching muscle is normal, but discontinue or reduce the degree of the stretch if any sharp pain is felt in the stretching muscle or adjacent joints.
Paul Kevin Smith has a M.Ed. degree in Kinesiology from U.T. Austin, and is an Adjunct Professor of Exercise Science at Austin Community College. He has several certifications in Exercise Physiology, Yoga, and Pilates, and is an authorized practitioner of the Functional Movement Screen. Contact him via www.paulkevinsmith.com, or Instagram at @pksmithatx.
- American College of Sports Medicine: ACSM’s Resources for the Personal Trainer. Philadelphia: Wolters Kluwer, 2018.
- Hindle, Kayla B., Tyler J. Whitcomb, Wyatt O. Briggs, and Junggi Hong: “Proprioceptive Neuromuscular Facilitation (PNF): Its Mechanisms and Effects on Range of Motion and Muscular Function.” Journal of Human Kinetics. 2012 March; 31: 105-113.