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News - Stretching can cause harm?!?

View the Mail OnLine article here

Well it's come full circle again; to adopt a turn of phrase, ‘ to stretch or not to stretch? That is the question '. I read the news article and could not help but wonder if it actually provided the full context within which the researchers presented their findings or if the researchers had any input in the way in which the information was put forward. For years it has been suggested that it is always good to stretch before activity……..indeed, that kind of advice is ingrained into any type of fitness and rehabilitation programme.

The article appears to suggest that joints are these ‘things' that are moved around by muscles and their tendons without natural restriction. Unfortunately the write up does not mention that fact the joints exist within a compact covering called a joint capsule which seals the joint and is the source of a necessary addition to joint function called synovial fluid (joint lubrication). The range of movement of joints is limited by the tightness of capsule and also, most types of joints, ligaments and not by the muscles as the article suggests! Muscles only allow the joint to move through its available range of movement, the direction of which is determined by the net force generated by contraction/relaxation of both the primary mover of the movement (muscle contraction) and the regulator (opposite muscle group relaxation). Problems occur when there is an imbalance between the rates of contraction and relaxation between the two.

Furthermore the article does not differentiate between self activated stretch (active) or passive stretching (passive). Structures behave differently in that when an individual performs a stretch on their own (active) the movement requires movement in the joint, muscle activity in the opposing muscle group (the regulator) and nerve supply. In contrast when the stretch is performed on an individual there will be very little (if any) contraction in the opposing muscle group. This does, therefore mean that in the first instance it is very unlikely that an injury will occur during an active stretch because the activity will be shut down as soon as any discomfort is detected.

The fact that the news item suggests that stretching makes tendons less elastic is too bold a statement when later implying that stretching for less than 45 seconds is less problematic. I am afraid to say that this is true for everything that has elastic properties. There is a biomechanical principle called Elasticity and all human tissue demonstrates this very well. An example of what this is all about is to stretch an elastic band between two hands and then to gently ease the pressure off; if you release the stretch soon enough the elastic band will resume its normal length. Hold it stretched for too long and it will not! When it does not return to its normal length the integrity of the elastic band is compromised and it feels very week and feeble. Muscles, tendons and other soft tissue behave like this but all at different rates. The stronger the tissue the less resistant it is to stretch hence ligaments that help protect joints exhibit the least amount of elasticity; that is why they protect and regulate excessive joint movement in any direction. Contrary to the impression given by the news item, the muscles/tendons don't do this.

The news item does not clarify many issues that may or may not be within the original researchers' article for instance, the type of training the athletes did, the type of athlete, whether they are all of one gender or not, if the method of measuring ‘strength' and ‘length of stretch' were the same in all articles viewed etc. There are several factors that may influence the outcome of the tests. And most importantly is the 8.3% difference in strength generated by individuals who stretched before exercising either statistically significant enough to suggest a real change between comparison or clinically significant that warrants a complete review of clinical practice. I for one would like to know before accepting the premise that a stretch could be harmful and I would hate to see an upsurge of patients injuring themselves because they misunderstood the message.

So, ‘ to stretch or not to stretch? ' my answer will be unequivocal, yes but never for more than 30 seconds! Take note and beware!!

© Dr A. A. Aluko, April 2013

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