Mel C Siff PhD
Partial extracts based upon my lectures and workshops delivered at NSCA (National Strength & Conditioning Association) Conventions in 1988 and 1989, as well as on material in the book "Supertraining" (Siff & Verkhoshansky, 1999). Do not regard this brief summary as comprehensive; for many more details of how PNF may be used in applied sporting situations, consult "Supertraining".
Strength training is often regarded as a discipline confined largely to the gymnasium or sports field. Unfortunately, this can obscure the fact that it can and does appear in other situations which have little direct connection with sport.
In particular, PNF (Proprioceptive Neuromuscular Facilitation) contains many useful techniques which can play an important role in the strength training of athletes. It is one of the aims of this article to show that PNF is a comprehensive conditioning system which includes not only many of the principles already covered in the "Supertraining" book, but also adds insights which complement these principles.
PNF is invariably regarded by conditioning coaches as a special type of sophisticated stretching, alongside static, ballistic and passive stretching. PNF is far more than just another stretching technique; it is actually an entire system of therapy comprising a broad spectrum of different techniques and procedures for rehabilitating patients suffering from various musculoskeletal injuries or disabilities. Stretching constitutes but one of many aspects of the full repertoire of PNF methods, yet even those enlightened coaches who use PNF extol only its virtues as a stretching system.
Essentially, PNF recognizes that all physical conditioning depends primarily on neuromuscular processes involving sensitive receptors (proprioceptors) in the muscles, tendons and joints which enable a person to stabilise and move the body and its parts in space and time. Appropriate recruitment of the various stretch reflexes of the body, therefore, forms a vital part of PNF conditioning.
Definition and Scope of PNF
Formally, PNF is defined as a system for promoting the response of neuromuscular mechanisms by stimulating the proprioceptors. Knott and Voss state quite simply that PNF techniques involve placing a demand where a response is required. Its relation to the well-known SAID (Specific Adaptation to Imposed Demands) principle then becomes clear.
Essentially, two types of PNF may be recognised: classical PNF and modified PNF. The former refers to the hands-on clinical approach described in the Knott and Voss text, while the latter refers to an approach which adapts certain PNF techniques and principles for application by hand or apparatus in physical conditioning (as covered in my workshops for the NSCA).
In applying classical PNF, the physical therapist stabilises specific parts of the body with the hands or body, while the other hand is used to grip the extremity or relevant part of the limb of the patient to offer highly specific patterns of resistance.
PNF stipulates that the muscle contraction must be maximal throughout the current range of movement, thereby ensuring that summation occurs at all times. Summation refers to the adding together of individual muscle twitches to produce strong, cooperative muscle movements. It occurs by imposing exercise of high intensity or prolonged duration to increase either the number of motor units contracting simultaneously or their rate of firing (or both).
At times, the therapist will produce a strong involuntary contraction in a debilitated muscle by imposing a sharp jerk during extension of the joint, thereby eliciting the myotatic stretch reflex produced by the muscle spindles. . . . PNF recognizes that the myotatic stretch reflex actually consists of a short duration, phasic stretch reflex and a longer duration, weaker tonic stretch reflex (see Fig 3.33, "Supertraining"). Consequently, short and long duration stretching loads are imposed in PNF to achieve different muscular responses. At other times, resistance will be increased or prolonged so as to enhance activation of the Golgi tendon reflex, thereby tending to reduce the tension in a muscle and promote local relaxation, which is sometimes desirable in facilitating the execution of a certain pattern (see Fig 3.33).
PNF also relies on the phenomenon of reciprocal inhibition in which strong contraction of the agonist muscles causes reflex relaxation of the antagonist muscles to prevent the latter from being injured. Application of this technique can produce a significantly stronger contraction of the agonists.
In the clinical setting, PNF requires the therapist to make regular use of verbal and non-verbal signals, including contacts with the hands or highly specific spoken commands to direct, instruct and motivate the patient. Sometimes, PNF implements various supplementary methods to augment facilitation produced by other primary means. These include the use of vibration, massage, ice, heat, electrostimulation, ultrasound or stroking.
The discipline of PNF teaches therapists to apply repetitions of graded resistance, to incorporate phases of relaxation, to elicit reflexes to facilitate contraction and greater range of movement, to impose specific patterns of passive and active movement, to use supplementary procedures for enhancing performance and to generally stimulate all neuromuscular processes related to voluntary and involuntary movement. No training method could be required to offer much more than this repertoire to qualify as an all-round conditioning system.
The Fundamentals of PNF
PNF may be categorised in terms of five P-factors: Principles, Procedures, Patterns, Positions and Postures, with joint Pivots and Pacing (Timing) as important sub-categories. The methods comprising these factors were formulated from findings on neuromuscular development, such as the functional evolution of all movement from motor immaturity to motor maturity in the growing child or novice athlete in definite sequences progressing logically from:
* total to individuated
* proximal to distal, distal to proximal
* mobile to stabile
* gross to selective
* reflexive to deliberate
* overlapping to integrative
* incoordinate to coordinate
The Principles of PNF
The basic principles of PNF may be summarised as follows:
1. Use of spiral and diagonal movement patterns
2. Motion crossing the sagittal midline of the body
3. Recruitment of all movement components (e.g. flexion-extension)
4. Exercising of related muscle groups
5. Judicious eliciting of reflexes
6. Movement free of pain, but not free of effort
7. Comfortable full-range movement
8. Application of maximal resistance throughout the range of non-ballistic movement
9. Use of maximal resistance to promote overflow (irradiation) of muscle activity
10. Use of multiple joint and muscle action
11. Commencement of motion in the strongest range
12. Use of static and dynamic conditions
13. Appropriate positioning of joints to optimise conditioning
14. Exercising of agonists and antagonists
15. Repeated contractions to facilitate motor learning, conditioning and adaptation
16. Selection of appropriate sensory cues to facilitate action
17. Emphasis on visuo-motor and audio-motor coordination
18. Use of distal to proximal sequences in neuromuscularly mature subjects
19. Use of stronger muscles to augment the weaker
20. Progression from primitive to complex actions
21. Planning of each phase to lay foundations for the next phase
22. All activities are integrated and goal directed
23. Use of adjunct techniques (e.g. massage, vibration).
Immediately it may be seen that employment of any of the above principles in training implies conscious or unconscious reliance on aspects of the PNF system.
Procedures of PNF
The procedures (or techniques) used in PNF include:
1. Use of specific manual contacts with the body to facilitate and guide movement
2. Application of maximal tolerated resistance
3. The use of oral commands and non-verbal cues to facilitate correct movement
4. Eliciting of maximal stretch reflex in the lengthened muscle range
5. Use of appropriate timing and sequencing of all actions
6. Application of traction or approximation (compression) to stimulate joint receptors
7. Inclusion of recuperative motion to manage fatigue produced by resisted activity
8. Use of Specific Activation Techniques to develop full range of voluntary movement
9. The use of Specific Relaxation Techniques.
The Specific Activation Techniques(of 8 above) need to be elaborated upon, as follows:
* Repeated Contractions (RC)
Repetition of muscle contraction is necessary for motor learning and the development of strength, muscle endurance and flexibility. PNF uses precise sequences or patterns of isometric, concentric and eccentric contraction, sometimes augmented by eliciting various neuromuscular reflexes (i.e. methods similar to some types of plyometrics).
* Rhythmic Initiation (RI)
This technique employs phases of voluntary relaxation, passive movement and repeated dynamic contractions of the major muscle groups involved in the agonistic pattern of movement.
* Reversal of Antagonists (RA)
This action occurs naturally in numerous activities such as walking, running and sawing wood. If the antagonists do not reverse competently in terms of strength, speed and coordination, motor efficiency is impaired. PNF uses three methods of reversal: slow reversal, slow-reversal-hold and rhythmic stabilisation.
Slow reversal (SR) involves dynamic contraction of the antagonist slowly followed by dynamic contraction of the agonist. Slow reversal-hold (SRH) employs dynamic contraction followed by isometric contraction of the antagonist, finally followed by the same contraction sequence for the agonist. Rhythmic stabilisation (RS) involves isometric contraction of the antagonist, followed by isometric contraction of the agonist, thereby producing co-contraction of the antagonists.
The Specific Relaxation Techniques (of 9 above) similarly need to be expanded upon, since they include the so-called PNF stretching techniques popularly used in athletic conditioning.
* Contract-Relax (CR), which involves a dynamic contraction of the antagonist against maximal resistance, followed by a phase of relaxation. This technique is repeated several times beginning and continuing from a point where the limb concerned is moved to its limit of pain-free action. The practitioner resists the contraction as strongly as possible and then instructs the client to relax before decreasing the force and waiting for the relaxation to occur. The limb is moved passively to its new limit of extension and the process is continued gently for a few repetitions.
* Hold-Relax (HR) is similar to contract-relax except that isometric rather than dynamic contraction against maximal resistance is applied at the limit of the client's movement before relaxation is commanded.
* Slow-Reversal-Hold-Relax (SRHR) comprises four stages: dynamic contraction of the antagonists involved, isometric contraction of the antagonists, brief voluntary relaxation, and finally, dynamic contraction of the agonists. These stages are applied to the muscles in the specific pattern needed to relax the group of muscles concerned, using several repetitions to enhance functional flexibility.
Patterns of PNF
Probably the most neglected aspect of PNF by coaches is the employment of specific patterns of joint and limb movement to recruit and condition muscles in the most efficient or appropriate manner. . . . .
In conditioning the developing neuromuscular systems of the patient, the novice or the child, there is always an emphasis on progression from primitive to complex, gross to individuated, mobile to stabile, reflexive to deliberative, proximal to distal, and incoordinate to coordinate. Contrary to common belief, the novice must be taught from a base of mobility to progress to stability, just as an infant learns to stand by first moving, staggering and exploring the environment.
The importance of these patterns cannot be overestimated, since they can enhance the effectiveness of any training session. They stimulate more thorough involvement and motor development than the less-than-optimal patterns imposed by the abundance of linear or cam machines on the market. No machines other than the traditional high-low pulley machines allow the user to produce PNF patterns.
Even then, machine training is often not functionally similar to the natural patterns of exercise movement upon which PNF is based, so that it requires a disproportionate number of machines to approximate the training offered by free weight and pulley training in three-dimensional space under conditions of pacing or normal timing (yet another PNF principle). Normal timing refers to the timing of the phases of a movement or series of movements which occur naturally in a uninjured person carrying out a given activity efficiently and safely.
PNF offers an enormous repertoire of patterns including those for sitting; sitting up; sitting up and rotating; standing; kneeling; crawling; raising the head; moving the arms from above to below and vice versa; raising and lowering the legs; moving the trunk in flexion, extension and rotation; and raising or lowering the body. There are distinctive patterns for actions with straightened limbs, flexed limbs and extended limbs.
Since weight training is aimed at maximal muscle conditioning via the use of techniques experimented with by weightlifters, bodybuilders and powerlifters for many years on every conceivable type of apparatus, there is no better environment to apply modified PNF for improving overall conditioning. Brief examples of how PNF may be adapted for use in the gymnasium environment are given later (see Ch 7.3 in "Supertraining"), but space does not permit a full description to be given of how PNF techniques may be integrated into most resistance workouts. For further information, the videotapes on applied PNF training prepared by the NSCA may be consulted (Siff, 1989).
Positions and Postures of PNF
Positions and postures are an integral part of the use of PNF patterns. The body and its limbs have to be held in carefully prescribed postures, with the joints and limbs maintained in certain positions or moved from position to position to establish stability of some systems and mobility of others in order to enhance neuromuscular development and safety. All action can then take place around specific joints as pivots. . . . .
Pacing in PNF
Normal timing or pacing refers to the timing of the phases of a movement or series of movements which occur naturally in an uninjured, healthy person carrying out a prescribed activity efficiently and safely. The optimal timing of each phase of any movement is vital for all neuromuscular conditioning, functional strength development and perfection of motor skill.
Modifications to PNF
Modified PNF refers to the adaptating classical PNF for use in the athletic conditioning setting or fitness class. Not only does it modify some PNF partner stretches for use by unassisted individuals, but it can also include application or adaptation of any of the PNF Principles, Procedures, Patterns, Positions and Postures in the normal conditioning environment.
Pulleys and dumbbells are especially suitable for application of the spiral and diagonal, midline-crossing PNF techniques. . . . . (examples given in textbook).
Pattern Deviations and Safety Factors
It should be remembered that the patterns of PNF were devised for rehabilitation, not elite sporting training, so that it is not incorrect to employ patterns of movement which may deviate significantly from those stipulated in PNF. . . . There are times when forceful or rapid movements have to be executed with the distal extremities far from the relevant joints, thereby imposing large torque on these joints. . . . .
As in engineering, one must plan for a certain safety factor which allows the athlete to manage even larger forces than those which may be encountered in competition. For example, a safety factor of 1.2 means that a system can cope with a maximal loading of 0.2 or 20% greater than normally expected. The appropriate use of heavy supplementary resistance training ('cross training') can be especially valuable in this regard, provided that it does not alter the neuromuscular patterns needed in the given sport . . . .
Far too many athletes believe that increase in strength and bodymass will automatically protect them from injury. If one executes a movement in an inefficient manner or reacts too slowly to produce adequate force, then even gigantic strength or structural bulk can be inadequate to prevent injury.
Functional Neuromuscular Conditioning
Although some members of the strength conditioning profession have used the term 'modified PNF' for many years, its appropriateness needs to be re-examined for several reasons.
Firstly, it is sometimes desirable to deviate from strict PNF principles to achieve a specific goal. Secondly, there are other movement disciplines such as Feldenkrais, Alexander, yoga, Tai Chi and Laban which offer invaluable additional methods of conditioning the body. Thirdly, PNF might not only involve neuromuscular processes, since contractile activity in a muscle may be facilitated by local after-discharge of the same muscle. Fourthly, the PNF repertoire includes methods which may not be classified accurately as proprioceptive, such as cognitive, perceptual and other sensory mechanisms. Finally, the term Proprioceptive Neuromuscular Facilitation is too technically daunting for the average coach or athlete.
Therefore, I propose that the term Functional Neuromuscular Conditioning (FNC) might be more appropriate, since PNF and other movement disciplines all stress the importance of optimising the conditioning effect to produce functional fitness of the neuromuscular system. Because Wolff's Law states that function precedes structure, FNC may be seen to embrace all-round development of function and structure. In other words, FNC should be regarded as an entire conditioning system capable of developing any desired type of musculoskeletal fitness.
Siff M C & Verkhoshansky Y V "Supertraining" 1999
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