Proprioceptive Neuromuscular Facilitation (PNF) encompasses a broad treatment approach to facilitating proper muscular function. There are many methods within this umbrella term.
Some methods are designed to strengthen muscles whereas other methods are designed to free restricted neuromuscular patterns. Many physical therapists learn the former methods mentioned, whereas massage therapists may be trained on the latter methods.
PNF methods were first devised by Herman Kabat, MD, PhD, Margaret Knott, PT, and Dorothy Voss during the 1940s and 1950s, and were based upon the neuromuscular theories of Sir Charles Sherrington from earlier in the century. Sherrington’s laws of neurology, including irradiation, successive induction and reciprocal inhibition, became the foundation for early PNF treatment methods.
Initially, PNF was employed to assist paralysis patients due to polio and related injuries. Years later, PNF methods were utilized by physical therapists as a supportive treatment option in movement and therapeutic exercises.
Benefits of Stretching
PNF methods complement traditional stretching performed by massage therapists. According to the Mayo Clinic, the top five benefits of stretching include:
• Increased flexibility and joint range of motion. Flexible muscles can improve your daily performance. Daily functional tasks become easier and less tiring. Flexibility tends to diminish with age but can be regained and maintained.
• Improved circulation. Stretching increases blood flow to your muscles. Improved blood flow brings more nourishment, rids metabolic waste out of tissues and shortens injury recovery time.
• Better posture. Good posture alleviates painful discomfort and chronic holding patterns within the body. When long-held chronic tension has alleviated, the body’s parasympathetic mode can restore homeostasis.
• Stress relief. Stretching relaxes tight, tense muscles that often accompany stress.
• Enhanced coordination. Maintaining full range of motion through joints keeps you in better balance. Coordination and balance will keep you mobile and less prone to injury from falls, especially as you age.
Examining the anatomy and physiology involved with PNF methods answers how using PNF will accomplish these benefits. There are two key principles working in conjunction with PNF style stretching: reciprocal inhibition and post isometric relaxation. These principles allow PNF style stretching to utilize the effectiveness of the nervous system to augment the effects of traditional simple stretching. Any stretch may be enhanced with the PNF methodology applied.
Reciprocal inhibition: This principle describes how a muscle relaxes when its antagonist contracts. Neurologically, an afferent (sensory) message from a muscle is brought into an interneuron within the spinal column. Because interneurons are inhibitory by nature, the efferent (motor) signal from the spinal column will cease contraction of the muscle’s antagonist.
Example: The anterior deltoid muscle, a shoulder flexor, will relax when the posterior deltoid, a shoulder extensor, contracts.
Post isometric relaxation: This principle describes the three- to five-second window of time in which a muscle fully relaxes after its contraction ceases before the muscle’s tonus is restored. This allows the body to reset its proprioception.
What Happens During a PNF Stretch?
When one first stretches a muscle, not all fibers stretch simultaneously. Some remain at rest. The length of an entire muscle depends on the number of stretched fibers.
When a stretch occurs, there are two types of mechanoreceptor cells at work: Golgi tendon organs and muscle spindle cells. These cells perceive one’s own body position and movement by detecting changes in tension placed upon joints and muscles.
Golgi tendon organs are effective at ensuring a muscle does not have too much load placed upon it. These cells communicate within spinal gray matter. When gray cells perceive a muscle may be damaged due to excessive load, the spinal cord sends a message to the muscle to relax. This is termed an inverse stretch reflex.
Muscle spindle cells aid in maintaining muscle tone and ensuring our muscles never over-stretch. These cells also communicate with the spinal gray matter. When gray cells perceive a muscle is stretching beyond its limit, the spinal cord sends a message to the muscle to contract slightly. This is termed a myotatic stretch reflex.
In addition, the Pacinian and Ruffini joint nervous organs impact the ability of joints to remain steady and static during stretches. Pacinian organs are active with rapid, quick joint movements. Ruffini organs are active with slower, measured joint movements. If these organs cannot facilitate proper signaling, the joints stretched may exhibit an abrupt or interrupted end-feel, the sensation felt when a limb is stretched to its limit.
If stretching is performed slowly on a daily basis, the mechanoreceptor cells become accustomed to the new proportions of length within muscles. This is why daily stretching is key in achieving maximum results of improved flexibility and range of motion.
[Visit the International PNF Association’s Open-Access Research Page for literature on PNF.]
Depending on the PNF method utilized, a practitioner may choose to engage a muscle with either an isometric or concentric muscle contraction. An isometric contraction involves a muscle held in a fixed position as it contracts. A concentric contraction involves a muscle shortening upon its contraction. Whether the contraction is isometric or concentric, only a slight contraction (about 10% of strength offered) is enough to engage the nerve cells involved to make PNF methods effective.
Full-force contractions may easily lead to injuries during the treatments and are unnecessary to accomplish the goals of PNF methods. Advising a client to exert a slight contraction at most will avoid injuries during PNF stretching.
There are many different types of PNF methods that can be learned. Physical therapists will learn methods to strengthen muscles adversely affected by injury, trauma and/or medical conditions.
These strengthening methods will help clients who need greater range of motion develop muscle strength and endurance, and better continuity between agonist and antagonist muscles. Clients rehabilitating from injuries will greatly benefit from improved muscle strength after muscle atrophy has occurred.
Both physical and massage therapists may learn PNF methods to relax certain muscle regions for similar benefits. Clients experiencing chronic pain will benefit from the relaxation effects provided. Functional improvements in daily tasks will be witnessed as muscles have improved efficiency. Better flexibility of joints and muscles will aid proprioception and movement patterns, especially in people who are relearning how to walk and use their bodies after accidents.
About the Author:
Jimmy Gialelis, LMT, BCTMB, is owner of Advanced Massage Arts & Education in Tempe, Arizona. He is a National Certification Board for Therapeutic Massage & Bodywork-approved provider of continuing education, and teaches “Professional Ethics for LMTs” and many other CE classes. He is a regular contributor to MASSAGE Magazine, and his articles include “Massage for Trauma: 3 Ways of Responding to an Emotional Release” and “Diabetes and Massage: What Therapists Need to Know” (both, massagemag.com).
• “Facilitated Stretching”, McAtee, Robert & Charland Jeff, 1999, second edition.
• Mayo Clinic: https://www.mayoclinic.org/healthy-lifestyle/fitness/in-depth/stretching/art-20047931, Staff, January 2020.