Is there a point to stretching?
Physiotherapists, coaches, personal trainers and many others have advocated stretching as part of a sport specific warm up/cool down program. Others such as yoga and pilates instructors have prescribed stretching while in pursuit of various fitness goals. All of us will have all heard the testimonials from people who believe that lack of stretching was responsible for a particular injury they suffered.
However, recent research has suggested that stretching might not be all we thought it was. Through this blog I will re-examine the role of stretching and provide a summary of the scientific evidence and my interpretation on these findings as they relate to stretching.
As a starting point, let us ask ourselves why we stretch?
The most common responses to this question include:
- To reduce the risk of injury
- To enhance performance
- To reduce pain and stiffness
- To lengthen muscles
- To enhance tissue healing
Let me address each of these responses individually:
Reduce the Risk of injury.
Studies suggest that stretching before exercise does not prevent injury. One such comprehensive study investigated the effects of stretching and not stretching on Australian army recruits. They investigated 1538 subjects which represents a comprehensive cohort. The investigators found no reduction in the risk of injury associated with exercising when they compared a group who stretched against a control group who did not stretch. In another publication produced by the researcher, Shrier, he performed a comprehensive review of the scientific literature relating to stretching and injury. He reported that stretching before exercise, either increased the risk of injury or made no difference to the rate of injuries.
To enhance performance.
Research has shown that following static and repeated stretching a muscle will actually weaken. This weakening effect can last for anything between 15 minutes up to 2 hours. It has therefore been suggested that if a muscle has weakened with the stretching effect then it may not be prudent to exercise immediately post stretching. On balance, review of the scientific literature suggests that static stretching has a negative effect on the subsequent performance of activities especially activities that involve a stretch reflex mechanism, e.g. sprint, high jump, basketball etc…
To reduce pain and stiffness
It is a general held belief that stretching will limit or alleviate post exercise soreness, often referred to as DOMS (delayed onset muscle soreness). Research has shown this not to be the case. Following on from this, where an injury has occurred with activity and an acute inflammatory event has begun it would be advised to refrain from any activity that will apply a load or stress to tissue and as such stretching should not be applied in the acute phase of an injury, i.e. first 3 days after the injury has occurred.
To lengthen muscles.
From my 24 years of clinical observation it is my belief that shortening of muscles is relatively uncommon. In most instances what I observed is that the resting tone (tension) for a muscle may be too high. All muscles have a resting have tone. You can consider ‘tone’ as a measure of the resistance within a muscle to lengthening. Too much or too little tone is a bad thing. At one end of the spectrum we might have a spastic muscle with very high tension or at the other extreme a very floppy or ‘flaccid’ muscle.
So ‘short muscles’, are really muscles sitting with increased tone. The causes behind this increased tone are varied. Frequently it is associated with poor / inefficient movement patterns. These inefficient movement patterns may be, (a) learnt, i.e. occur with motor development or (b) acquired following injury or associated with pathology.
There can be other reasons behind changes in muscle tone that your physiotherapist might diagnose with clinical reasoning and physical examination which can be discussed with you when needed.
With regards to points (a) and (b) above, I believe the best treatment approach is to alleviate the abnormal movement pattern. This means that when we teach you to move with improved efficiency, your muscle tone adapts and lets you maximise ‘your flexibility’. We are not all designed to touch their toes or do the splits. What we want to achieve is your maximum movement potential.
To highlight some of the positives that studies have demonstrated regarding stretching and improved movement. There have been a number of studies that highlighted that static stretching can result in a greater range of motion (ROM) about a joint. The studies noted that stretching had different effects on different muscles and that some responded to longer stretching to facilitate an improved ROM. What this research into static stretching did demonstrate was that the improved ROM occurred as a result of a change in tolerance to stretching and not due to any increase in the internal properties of the muscle (lengthening of muscle). In summary, the current the best theory is that stretching increases your ‘stretch tolerance’, either by decreasing the pain threshold, and/or decreasing the muscles resistance to stretching. It does the latter by temporarily altering the receptors in your muscles, tendons, and ligaments that usually react to stretching by making your muscles tighten up. There are a lot of possible mechanisms, and we don’t quite understand it all yet. Therefore, if you are going to attempt to improve your ROM of a joint via static stretching then you should perform stretches on a daily basis. These stretches should begin after first performing a 5 minute warm-up. You must hold the stretch for 30 seconds and repeat 4 -5 times. This will produce changes in ROM in less than 6 weeks.
To enhance tissue healing.
The importance of stretching during the recovery from a muscle strain/pull/tear is widely accepted and justified by research. Following injury the body lays down scar tissue. This is initially disorganised and immature. As tissue healing progresses it is important that this scar tissue is appropriately aligned and is at a good resting length. During the maturation phase of tissue recovery the scar tissue can be modelled and as such applying a biomechanical load along the lines of stress via stretching will facilitate a correct healing sequence. Therefore stretching is appropriate at certain times in the remodelling phase of tissue repair
Following from the above information the next question might relate to Dynamic stretches and their effects.
It would appear that dynamic stretching can encompasses most aspects of functionality without any negative effects on reaction time. An athlete could conceivably be more prepared physiologically to perform their required activity by implementing aerobic activity and sport specific dynamic stretch to increase blood flow, flexibility, and priming the body for imminent sporting activity.
The effects of warming up (increasing body temperature and blood flow) appropriately has been shown to reduce the risk of injury and therefore dynamic stretching might be effective in that it falls into this category. The key here is not to tire the body through an excessive warm up.
So to conclude this complex area around the need to stretch.
It is important that the hundreds of published articles investigating the effects of stretching are critically reviewed. Those studies that support the use of stretching as a method of limiting injury are numerous however these studies tend to show at least one other effective co-intervention. What this means is that there were other interventions/factors that could be responsible for limiting injury rates. When these variables are accounted for through appropriate analysis then there remains little experimental evidence that stretching before exercise prevents injury or facilitates performance enhancement.
Another criticism of the literature it is that not all sports are adequately represented in the studies. Therefore performing activities that require a significant range of motion (e.g. gymnastics) may in the future show that stretching is beneficial.
What is known however is that were you are performing activities that requires explosive power or muscle strength/endurance then stretching should not be used as part of the pre exercise regime.
I am aware that this information will challenge traditional approaches to preparing for exercise. What is obvious as a practitioner who has dealt with athletes and clubs is that quite often the principles of exercise are handed down through generations. I stretched, therefore I now encourage stretching. Research doesn’t support this and it is research that can drive us forward to better injury prevention.
I hope you enjoyed this review and continue to follow us on our future blogs.
Roberto Pelosi is a Masters qualified physiotherapist and is the owner of Premier Physiotherapy in Dublin, Ireland. He has worked and taught internationally including time with professional soccer clubs in the UK, Rugby league in Australia and toured extensively with Riverdance-The show.
He has a special interest in movement dysfunction and inefficiency and how it relates to injury and performance.