Sports PNF

An assistant supports a stretcher’s leg.

In Sports PNF, a group of muscles are flexed without moving, become more relaxed and are then stretched by the muscles on the opposite side of the joint. This is not only used for treating muscle cramps, it also helps increase range of motion. It is the safest PNF stretching technique because it reduces the risk of over-stretching. PNF is a physical therapy procedure designed in the 1940s and 1950s to rehabilitate patients with paralysis. In the 1980s, components of PNF began to be used by sport therapists on healthy athletes. The most common PNF leg or arm positions encourage flexibility and coordination throughout the limb's entire range of motion. PNF is used to supplement daily stretching and is employed to make quick gains in range of motion to help athletes improve performance. Good range of motion makes better biomechanics, reduces fatigue and helps prevent overuse injuries. PNF is practiced by physical therapists, massage therapists, athletic trainers and others.

An assistant helps a stretcher rest during a stretch.

Kinds of stretching

Dynamic stretching such as rapid downward bouncing while trying to touch the toes is dangerous. The muscle responds by getting shorter and so tense it might tear. Passive stretching is also risky. An assistant moves the limb for the individual and, not feeling the sensation, might overstretch the muscle. Nevertheless, it is often used in gymnastics. Static stretching is when the muscle is slowly lengthened a comfortable amount and kept that way for 15 to 30 seconds. In that time, the stretched feeling diminishes and the muscle is then slowly and comfortably lengthened an additional amount and held that way another 15 to 30 seconds. Proprioceptive neuromuscular facilitation (PNF) stretching takes advantage of two responses. When a muscle on one side of a joint contracts the nervous system causes the opposite muscle to relax. In addition, after a muscle contracts it becomes more relaxed than before. Thus, in this self-controlled method, a muscle is first contracted without moving the joint and is then stretched by the opposite muscle.

Research

After PNF stretching was in use by many people, scientific studies began to measure its effectiveness and test the theories it’s based on. PNF was found to work in shorter sessions than other methods. When an assistant is used, as with all methods, the risk of injury increases. The muscle contraction before the stretch increases blood pressure but probably not enough to be dangerous to people with high blood pressure. The studies also found that muscles are actually less relaxed following a contraction than after no contraction at all, so a PNF stretch may have a higher injury risk than a static stretch. Yet, when a fully relaxed muscle is stretched, much of the resistance is from the connective tissue, which can only be stretched so far. Both muscle and connective tissue growth is involved in any gains in flexibility made from stretching. Many scientists found PNF stretching to be more effective for increasing flexibility than other methods and many physical therapists consider it superior because it is similar to the motions of daily activities.

CRAC in general

The safest PNF is the CRAC (contract-relax, antagonist-contract) technique, because the partner, if one is used, makes no attempt to do the stretch. CRAC was found the most effective type of PNF for increasing range of motion. In its contract-relax phase, the muscle is first contracted. For this, the limb is traditionally pushed against something such as a partner, but when the limb is not weak this is a problem. This no-movement (isometric) contraction is held for about six seconds. The second step of CR is relaxation for safety. Since reversing direction too rapidly could cause injury, the patient or athlete takes a deep breath to insure the warmed-up muscle has time to fully relax. Next is the AC (antagonist-contract) phase. Now the muscle on the opposite side of the joint (the antagonist) is used to gently move the joint a little and thereby painlessly stretch the relaxed muscle for about six seconds. The C part of AC is another six-second contraction of the relaxed muscle that was just stretched. The entire CRAC (contract-relax, antagonist-contract) process is then repeated three to five times, or twice if the muscles are weak. The contractions are always done at less than full strength to prevent fatigue and soreness of the weak muscles, and if a partner is resisting stronger isometric contractions, the partner keeps good posture to prevent getting injured or excessively fatigued.

History

In the early to mid 1900s physiologist Charles Sherrington popularized a model for how the neuromuscular system operates. Irradiation is when maximal contraction of a muscle recruits the help of additional muscles. Reciprocal innervation causes one muscle to relax when its antagonist contracts, allowing a joint to bend. Successive induction is the contraction of one muscle followed immediately by the contraction of its antagonist, and this promotes strength and flexibility. Based on that, Herman Kabat, a neurophysiologist, began in 1946 to look for natural patterns of movement for rehabilitating the muscles of polio patients. He knew of the myotatic stretch reflex which causes a muscle to contract when lengthened too quickly, and of the inverse stretch reflex, which causes a muscle to relax when its tendon is pulled with too much force. He believed combinations of movement would be better than the traditional moving of one joint at a time. To find specific techniques, he started an institute in Washington, DC and by 1951 had two offices in California as well. His assistants Margaret Knott and Dorothy Voss in California applied PNF to all types of therapeutic exercise and began presenting the techniques in workshops in 1952. During the 1960s, the physical therapy departments of several universities began offering courses in PNF and by the late 1970s PNF stretching began to be used by athletes and other healthy people for more flexibility and range of motion. Terms about muscle contraction are commonly used when discussing PNF. Concentric isotonic contraction is when the muscle shortens, eccentric isotonic is when it lengthens even though resisting a force, and isometric is when it remains the same.

Spiral diagonals

PNF stretching is not only self-powered. It is based on spiral-diagonal patterns of movement, since arms and legs don’t just move in one or two planes. Their motion has both a spiral and a diagonal component. PNF is similar to normal motions found in sports and other physical activities. There are eight PNF stretching exercise patterns which move through all three planes of length, width and height. This is done be flexing or extending the elbow or knee, abducting or adducting the shoulder or hip and rotating the arm or leg from front to back and vice versa, giving eight motions. The foot moves from front to back with and without the legs crossing, and the hand moves from high to low with and without crossing in front of the body. The stretch occurs at the extreme ranges of the limb’s motion by flexing antagonist muscles. Four spiral diagonal motions are done both ways, making eight, to get into the stretching positions. The names of the four arm motions are: self-feeding, swimmer’s stretch, drawing a sword and sheathing a sword. Each group of muscles is first fatigued by no-motion contraction, stretched without pain by antagonist muscles and then isometrically contracted again. The leg motions back or forward and crossing the other leg in front are called: toe-off and soccer kick respectively. Those crossing in back are called: turnout when going back and snow plow when going forward. CRAC is followed for maximum effect. For example, before the back of the leg is stretched by the front of the leg, its muscles are contracted for about six seconds to reduce their resistance to the stretch. The person stretching lies on a table if being helped by a professional. Proper stretches are pain-free.

Therapy

Skilled practitioners employ many PNF techniques to help restore an injured area to pre-injury status. It’s used to help patients who have had a burn, torn rotator cuff, fracture, stroke or other injury. Over-use sport injuries happen when the athlete increases the intensity or duration of the exercise too much. The injured area must be rested long enough to heal and avoid re-injury. Ice packs and flexing the muscles in the area help reduce the inflammation. Once most of the swelling has gone, warmth can be applied and PNF stretching done. After joint mobility is fully restored, the weak muscles can be strengthened efficiently using PNF motions. For example, a trained clinician, while guiding the re-strengthening program of a baseball pitcher’s injured shoulder, stresses full range of motion. Typical PNF begins by placing a heat pack on the shoulder for 20 minutes. Techniques to move the arm without pain into stretching position are then employed. The stretching is alternated with the strengthening. This is guided by the clinician. An ice pack is placed on the shoulder for 20 minutes and the PNF ends. The rehabilitation session also includes weight lifting and cardiovascular conditioning. Recovery is faster if the body is in good shape. The therapy progresses after the injury is healed to sport-specific training such as pitching a light-weight ball and then a heavier one. This is worked on three times a week during the time of the appointments along with the other exercises.

Grouped muscles

To increase strength and coordination the entire range of motion is used. For PNF stretching, only the extreme positions are needed. These are:

• Arm up to the front.
• Arm down.
• Arm up to the side.
• Arm down crossing to the other side in front.
• Leg with foot in front of other foot.
• Leg straight back.
• Leg straight front near floor.
• Leg in back of other leg.

Before an arm or leg stretches, its muscles are flexed for about six seconds to limber them up. The patient or athlete waits a couple of seconds for the muscles to relax then rotates the limb gently, maintaining the stretch for about six seconds. The gentle stretch is repeated about four times with a few seconds of muscle relaxation between each time. Proper stretching is pain-free. The therapist if one is used provides isometric resistance for the limbering up and supports the limb in stretch position while the patient or athlete lies on a table.

Optimal ranges

The names of the muscles help those who often communicate about them. If the muscles are too small, the joints don’t straighten enough. There are also maximum ranges of motion. With the best possible range of motion, one’s foot would be able to bend upward about twenty degrees. While lying face up, the straight leg would be able to be at ninety degrees. One would be able to hold the knee with both hands above the center of the body. On the floor, the leg would be able to move to about forty-five degrees from midline. While lying sideways with hips bent, one’s upper knee would fit behind the lower leg’s knee. While lying face down, one’s leg would bend at the knee up and together. The ankle would be able to straighten about fifty degrees. The straight leg would be able to lift up to a thirty degree angle. If sitting on the floor with knees bent up, one’s face could get near the knees by bending forward. While standing, the waist can bend sideways a little to a pain-free end of range. While sitting or standing, the shoulder blades could move a little closer together and downward a little. While standing, one’s arm would move from 1) straight up, down and forward, to 60 degrees in back, from 2) straight up to down and forward across the chest at 45 degrees, from 3) straight sideways to straight across the chest, and from 4) down with the elbow bent sideways palm up to straight across the stomach. The muscles that pull the bones one way stretch the muscles that pull the bones the opposite way. Bending the elbow only, one would be able to touch the shoulder of the same arm. The wrist would bend up 70 degrees and down 80 degrees and bend, palm up, toward midline 30 degrees and away about 20 degrees.

Conclusion

Proprioceptive neuromuscular facilitation includes stretching techniques usable with healthy athletes needing more range of motion. The techniques are used by physical therapists, massage therapists, athletic trainers and others helping people stretch. The safest techniques have the athlete controlling the actual stretch rather than being passive. The muscle contracts and relaxes and its antagonist contracts (CRAC) to do the stretch. There are single-muscle at a time as well as spiral-diagonal CRAC stretches. The athlete’s own muscles are used for stretching during injury rehabilitation also. Good range of motion reduces fatigue and injury during athletics and improves performance.

Gallery

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  Arm-front diagonal flexion.
• 
  Leg-front diagonal flexion.

• PNF patterns (diagonal), lower extremities
• 
  Front cross
• 
  Out back
• 
  Back cross
• 
  Out front

• PNF patterns (diagonal), upper extremities
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  Cross low
• Back high
  Back high
• 
  Cross high
• Back low
  Back low

See also

• PNF
• Physical therapy
• Sports medicine
• Athletic training
• Massage
• Stretching
• Physical exercise

References

• McAtee, Robert E. Facilitated Stretching. Human Kinetics, 1993. Easy self-stretching with isometrics helps healing and prevents injury.