• Flexibility workshop
  • Part 1 - Learning about flexibility and stretching
  • Part 2 - Why does it seem so hard to stretch?
  • Part 3 - Preparing to stretch
  • Part 4 - The fundamentals of flexibility training
  • Part 5 - Your first 3 basic stretches
  • Part 6 - Your next 2 stretches with variations
  • Part 7 - Understanding injuries
  • Part 8 - More stretches to add to your collection
  • Part 9 - High performance stretching with PNF
  • Part 10 - What to do if you can't even get into the starting position.
• Fighting fit

Part 9 - High performance stretching with PNF

So far we have looked at basic stretching techniques most of which have focused on passive stretching. In this article we look at a high performance stretching technique called Proprioceptive Neuromuscular Facilitation or PNF.

Before you get stuck in to this article please read the disclaimer.

In the previous articles in this series I have mostly discussed passive stretching. If you recall, passive stretching is holding extended postures in a relaxed fashion with no movement. I also mentioned that it is possible to include additional pressure being applied to a part of your body to increase the stretch, by having a partner push you into a stretch, for example. Go back and read Part 1 of this series for details of different types of stretching.

PNF stretching takes the basic idea of passive stretching but adds isometric contractions to the stretches to increase their intensity. Isometric contractions are muscular contractions that do not alter the length of the muscle. In the case of PNF you are actually contracting and stretching the muscles at the same time! This type of stretching has several advantages and disadvantages some of which are listed below.

Advantages:

• Stretches appear to be much more efficient and produce rapid and substantial gains in flexibility and range of motion
• PNF seems to improve stability surrounding joints and has other beneficial effects on strength such as increased strength at the limits of range of motion
• Interestingly, greater muscle relaxation can occur with PNF

Disadvantages:

• Stretches can become rather uncomfortable during the contraction phase
• Arguably the level of risk of injury is increased especially if proper form is not observed
• You may need assistance from a partner or some extra equipment to help in maintaining position during the contraction phase
• The contraction phase of PNF can cause people to hold their breath and for blood pressure to rise as a result

Before going any further I need to reinforce some of the points made above. I consider PNF to be more risky than basic passive stretching. I also consider it to be an advanced stretching technique. If you elect to try PNF I strongly suggest you do some research, take your time and watch out for the telltale signs of the onset of injury (refer to Part 7 of this series for information on injuries). Also, don't try PNF until you have some grounding in passive stretching.

One final warning - If you are under 16 years of age or are still growing don't perform PNF stretching under any circumstances.

What is PNF?

PNF as a means for increasing flexibility is actually a by-product of rehabilitation physiotherapies. PNF was developed in the USA in the 1940's as a means of rehabilitating people who had suffered from head or spinal injuries. PNF in its original form features complex movements but it also includes isometric contractions performed against some form of resistance. It is this part of PNF that has been adopted by people seeking gains in flexibility. When I refer to PNF I mean this fragment of the original PNF therapy.

There are a number of approaches to PNF which can be somewhat confusing. This is not helped by virtue of the fact that different authors use different names for the same approaches. I'm only going to discuss two PNF approaches here:

• Contract-relax
• Contract-relax-agonist-contract

Even though there are a variety of approaches to PNF there is an identifiable common framework to all of them. This basically involves assuming a stretched posture, performing some type of muscular contraction and then follow up with a final relaxed stretch.

Contract-relax

With this approach the practitioner assumes an initial passive stretch. The muscle being stretched is then subjected to an isometric contraction. After the contraction a further passive stretch is applied with a great deal of emphasis being placed on relaxation.

Note that this approach is sometimes called hold-relax. Also be aware that some definitions of contract-relax (CR) call for a concentric contraction of the agonists (the opposing muscles to the one being stretched) rather than an isometric contraction of the muscle being stretched.

Contract-relax-agonist-contract

This approach also goes by the rather wonderful acronym CRAC. The first part of CRAC is the same as contract-relax; a passive stretch and an isometric contraction of the muscle being stretched. However, this is immediately followed by a concentric contraction of the opposing muscles (the agonists). Finally, a deeply relaxed passive stretch is executed.

How does PNF work?

Good question!

In fact a number of things are happening and we have to introduce some new terms to explain them. Postcontractive reflex depression (or autogenic inhibition) apart from being a bit of a mouthful is the phenomenon whereby a muscle's resistance to being stretched is momentarily reduced after a strong contraction. I suppose one way of looking at it is that the muscle is too tired to resist!

The golgi tendon organ is a special sensory organ located at the point where tendons and muscles meet. When the golgi tendon organ is subjected to a force it sends signals to the brain which responds by inducing something called the lengthening reaction in the stretched muscle. In other words, the golgi tendon organ reports that the muscle has had a good deal of force applied to it and as a safety measure the brain allows the muscle to lengthen a bit. The contractions in PNF activate the golgi tendon organ and induce the lengthening reaction.

Combine postcontractive reflex depression with the lengthening reaction and you can see how the muscles give a bit more in PNF than in passive stretching alone. The passive stretching phase at the end of a PNF stretch serves to habituate the muscle spindles to fire less often and so the stretch reflex is reduced even further (see Part 2 for an explanation of the stretch reflex). All-in-all you have a truly powerful stretching technique in PNF.

References

If you want a top book on PNF I can strongly recommend 'Stretching and Flexibility' by Kit Laughlin (ISBN 0 7318 0602 6). Kit covers the theory of PNF and introduces PNF stretches for the whole body, not just the legs. The book also contains a comprehensive 'recommended reading' section for the more interested individual.

What next?

Tips and tricks for the 'hard gainer'.

 

 
Author: Andy French