Proprioceptive Neuromuscular Facilitation: The Foundation of Functional Training
Functional training has been utilized as part of performance enhancement and conditioning for years. It seemed to become more popular in the late 1980s and early 1990s as we moved from traditional fixed axis equipment into more fundamental and skill movements. Individuals such as Gary Gray and Vern Gambetta seemed to lead this shift in thinking on how we should be training our athletes and active individuals. As with all shifts in thinking, there is going to be some controversy in how functional training is defined, however the foundation should be based on enhancing overall movement. In order for the body to function properly, there must be cohesiveness between the muscles, joints and neuromuscular system.
When we look at training movement, we must have an appreciation of the fundamentals that create movement. It is important that some of the basic principles are incorporated throughout training in order to gain and maintain proper movement mechanics. The focus of functional training is to improve movement and respectable movement is based on a balance of mobility and stability. This balance requires effective proprioceptive communication between the muscles and joints. If there isn’t a balance of mobility and stability, then movement patterns will be dysfunctional. The dysfunction many times can be related to a disruption in the neuromuscular system. Improving this system should then create more effective movements. In order to improve the neuromuscular system’s effectiveness in coordinating movement, proprioceptive neuromuscular facilitation (PNF) concepts should be utilized.
PNF techniques have been around since the late 1930s and '40s when a physician and neurologist named Herman Kabat began using proprioceptive techniques on younger individuals with cerebral palsy and other neurological conditions. He found that by stimulating the distal segments, the proprioceptors in the more proximal segments became stimulated. The purpose was to enhance and create movement in areas where the neurological system has been compromised. His techniques were based on Sherrington’s principles of irradiation, reciprocal innervation and inhibition.1 These principles describe the rhythmic and reflexive actions that lead to coordinated motion.
PNF uses the body’s proprioceptive system to facilitate or inhibit muscle contraction. One of the pioneers in the use of PNF, Dorothy Voss, defined it as a method of promoting or hastening the response of the neuromuscular mechanism through the stimulation of proprioceptors.1 The muscles must work synergistically in order for movement to occur. This requires the muscles to have the reflexive ability to contract and relax in order to perform basic movements. Fundamental movements such as squatting, lunging and stepping are PNF patterns that all rely on the body’s ability to effectively create and control mobility and stability. When these movements become dysfunctional it can often be traced to a disruption in the body’s proprioceptive system, leading muscles to either be inhibited or not facilitated at the right moments. This causes an inability to create the balance of mobility and stability, improving this balance is the basis of functional training.
A problem many exercise professionals are faced with today is active individuals that have lost their ability to do the basic fundamental movements. Fundamental movements consisting of such as squatting, lunging, stepping and reaching, have become less efficient due to habits, poor training and/or injuries, causing postural and prime moving muscles to become less effective at performing their tasks. These problems have led individuals to create compensations, which sacrifice mobility and/or stability in order to complete a movement or task. For example, a person with poor mobility in their hips will sacrifice lumbar spine stability in order to squat down, lunge or step. It is important that these compensatory patterns are addressed prior to focusing on strength and power.
It is important that prior to prescribing PNF techniques, an appreciation of the fundamental movements that PNF is designed to correct is acquired. By first reviewing squatting, lunging, stepping and reaching patterns we can set a baseline in determining which movement is the most dysfunctional. The Functional Movement Screen is a tool that can be utilized to provide insights into which movement pattern is the most deficient.2 Once the deficiency has been identified, the next step is to determine if this is a result of a mobility or stability dysfunction. This will allow a more effective way to implement and progress PNF techniques. If the fundamental movements are not improved then the chosen technique may not be the most beneficial. Indications for PNF greatly depend on the desired outcome. Many times, PNF is used to increase flexibility, strength and coordination when there are deficiencies in the respective areas. It is thought that the education and reinforcement of repeated PNF patterns increases coordination while promoting joint stability and neuromuscular control.3 This same philosophy should be incorporated during functional training in order to effectively influence improved motor programming.
There are common principles that should be utilized when performing PNF techniques. The first is to have a complete understanding of the goals you are trying to accomplish with the technique. First, it is important to set a baseline of movement so you can determine which technique will be the best option to improve the dysfunction. Secondly, verbal and visual cues are crucial to elicit the proper neuromuscular response during the activity. The exercise professional should place themselves in the most effective position in order to be able to use proper hand positioning and mechanics. Finally, the distal segments should be facilitated first to allow proper irradiation to occur throughout the body, which is one of the most fundamental concepts of PNF.
PNF is divided into two areas, strengthening and stretching techniques and patterning. The ultimate goal is to improve movement patterns, so progressing from basic stretching and strengthening to patterns is very important. Establishing proper mobility of a joint and muscle must occur prior to strengthening the movement and/or pattern in order to create effective neuromuscular facilitation. Ensuring that the mobility is sufficient will allow more efficient transition into functional training. If the mobility isn’t established, movement compensations may arise during functional training. However, certain strengthening techniques are recommended under therapeutic conditions in order to sustain and influence muscle contraction.
The method of PNF is designed to have the maximum resistance throughout the range of motion of primitive patterns. The joint first begins at its strongest range of motion and proceeds weaker. PNF incorporates mass movement patterns that are diagonal and spiral in nature and often cross the midline of the body. Everyday tasks and skills, from picking up a bottle of water to throwing and kicking naturally utilize diagonal and spiral movements.
The techniques used for PNF strengthening replicate movements and muscle contractions of many physical activities. Rhythmic initiation is typically used to help aid the education of initiating a movement. It incorporates a passive, active assistive, active-resistive pattern and avoids reactive stretching. Slow reversal is used to aid in the coordination of an agonist and antagonist. It is performed by an antagonist contraction against resistance followed by an agonist pull. Strengthening at a specific range of motion can be completed with different methods. Repeated contraction requires a repetitive muscular contraction once the muscle becomes fatigued; it is supported by a stretch with a concentric and eccentric contraction through the range of motion.
The stretching techniques are most often used to inhibit spasticity. There are two inhibitory concepts that are applied during PNF stretching. Autogenic inhibition relies on the nerve fibers from a stretched muscle to cause that muscle to relax, thus allowing for a greater stretch. Reciprocal inhibition involves an agonist and antagonist effect. In order for an agonist to contract and cause movement, the antagonist incurs a reflexive relaxation to allow the movement. Prentice4 identifies the following PNF stretching techniques to increase muscular strength, endurance and coordination.
The Contract –Relax stretch is utilized for gaining range of motion restricted by muscular tightness. The patient should be taken into a stretched position. They are then instructed to isotonically contract against the resistance of a therapist, and then relax. The patient can then be taken back into the stretched position. Hold-Relax is a similar stretch to contract-relax, except the contraction occurs isometrically.
Slow reversal-hold-relax involves a contraction from both the agonist and antagonist. First, the agonist contracts to the joints capable range of motion, which causes the antagonist to relax and stretch. The agonist then relaxes while the antagonist isometrically contracts. The final step is another contraction of the agonist muscle. This stretching technique should be considered from the antagonist point of view, which is relax-contract-relax.
PNF patterning is used for the upper and lower extremities and is broken into to D1 (Diagonal 1) and D2 (Diagonal 2) patterns. The upper extremity pattern encompasses the shoulder, elbow, wrist and fingers. Similarly, the lower extremity pattern encompasses the hip, knee, ankle and toes. Each diagonal pattern can be completed into flexion as well as extension. The D1 shoulder flexion pattern starts in shoulder flexion, adduction and external rotation, forearm supination, wrist flexion and finger flexion. The ending position for D1 flexion is shoulder extension, abduction, external rotation, forearm pronation, wrist and finger extension.
The D1 Extension pattern reverses the D1 flexion pattern. D2 flexion includes shoulder flexion, abduction and external rotation, forearm supination, wrist and finger extension.
Again, the D2 extension pattern reverses the D2 flexion pattern.
The lower extremity diagonal patterns replicate those of the upper extremity, with the extension patterns reversing the flexion patterns. D1 flexion follows hip flexion, adduction and external rotation, ankle dorsiflexion and inversion and extension of the toes. D2 flexion includes hip flexion, abduction and internal rotation, ankle dorsiflexion and eversion and extension of the toes.
The chop exercise, commonly used in functional training, utilizes both D1 and D2 PNF patterns for the upper extremity. The angle of resistance is from the top, which allows the upper extremity to go through a functional pull to a press.
A lift pattern uses the same concept, utilizing the opposite D1 and D2 pull to press pattern respectively, with the resistance coming from the bottom. In a half-kneeling position, more stability is required, increasing the overall PNF required to achieve the movement.
A traditional PNF pattern used in functional training for the lower extremity is the crossover step. This movement requires both D1 and D2 patterning from each hip when performing multiple steps. In order to increase difficulty and PNF patterning, resistance bands can be used.
By placing the band around the waist, an increase in irradiation may occur which should increase the neuromuscular input required to perform the movement.5
Once PNF techniques are introduced, it is important to recheck the fundamental movements that were dysfunctional. This will ensure that mobility and/or stability issue that is being addressed are having a positive effect on movement. This type of systematic programming will allow continual feedback, where the progressions can be based on movement appraisal. When the fundamental improvements are seen, increases in resistance, agility and plyometric PNF techniques can be utilized to maintain and progress the individual.
PNF is designed to improve overall movements through proper neuromuscular facilitation or inhibition. In order for functional training to have the best results, fundamental movements must be adequate or compensations will arise. In many cases, the compensatory movements that occur are due to disruptions in the neuromuscular system. This may not be a flexibility or strength issue, the muscles do not facilitate or inhibit when needed, resulting in a mobility or stability problem. PNF is utilized to improve the balance of mobility and stability through strengthening and/or stretching movement pattern. In order to determine which technique is best suited for the individual, a baseline movement screen should be obtained. This initial step is necessary and highly recommended when prescribing PNF and functional training methods. It provides insight on the most dysfunctional area as well as quick feedback in determining if the technique provided positive results.
PNF has been a very important part of therapeutic techniques for years. More recently, the focus on functional activities has allowed the techniques of PNF to become an integral part of this type of exercise programming. PNF can and should be incorporated into any functional training, where the neuromuscular system is causing fundamental movement dysfunctions. These techniques should provide a more effective exercise program and system with which to progress
A great resource for additional techniques involving PNF would be:
Voss, D. E., Ionta, M. K., Myers, B. J. (Ed. 3). (1985). Proprioceptive Neuromuscular Facilitation: Patterns and Techniques. Philadelphia, PA: Harper & Row.
Cook, G. Baseline Sports-Fitness Testing. In: B. Foran, eds. High Performance Sports Conditioning. Champaign, IL: Human Kinetics Inc; 2001: 19-47.
Saliba, V., Johnson, G., Wardlaw, C. Proprioceptive Neuromuscular Facilitation. In: Basmajian J., Nyberg R. (1993). Rational Manual Therapies. Baltimore, MD: Williams & Wilkins.
Prentice, W. E. & Voight, M.I. (2001). Techniques in Musculoskeletal Rehabilitation. New York, NY: McGraw Hill.
Cook G, Fields K. Functional Training for the Torso. Strength & Conditioning.19:2;14-19,1997.