There’s no topic that divides the fitness world quite like stretching. Is it good for you, a waste of time, or something that should be avoided at all costs? In this post, I’ll be diving into the evidence for and against.
Do you stretch?
Should you?
As runners, it seems that an awful lot of us are either doing it or feeling guilty that we’re not.
When I was a beginner runner in the 1990s, the message was drummed into us that stretching was a vital component of training: to increase range of motion, improve performance and limit injuries.
And in a 2014 study, published in the Journal of Orthopedic and Sports Physical Therapy, when recreational runners were asked what they thought were the biggest risk factors for getting injured, ‘not stretching enough’ came up most often.
But in the last 15 years or so, there’s been an anti-stretching backlash, and the suggestion that it doesn’t really have any effect or might actually do more harm than good. That too much stretching can make your ligaments as baggy and saggy as an old sock, destabilising your joints.
So, what’s the truth? Well, it’s complicated.
The case against stretching
Lined up as witnesses for the prosecution are multiple studies that show that stretching:
Doesn’t do anything to lengthen muscles
Doesn’t protect against injuries
May have a negative effect on performance
Can stretching give you longer muscles?
Many of us stretch because we think it will lengthen out tight muscles. The bad news is that this isn’t borne out by research.
Studies show that any increase in muscle length after stretching is short lived – the muscles soon return to their original state. And while we may feel more flexible when we stretch regularly, one theory is that this is because we learn to tolerate the discomfort we feel when we push to the end of a muscle’s range of motion, rather than because the muscle itself is getting any longer.
If you’re a very dedicated stretcher – we’re talking about long hold stretches of several minutes, performed multiple times a day – there’s some evidence that you may be able to create more length in your muscles. But how many of us would want or be able to commit that much time to increasing flexibility?
And one final point: just because our muscles feel tight, doesn’t mean that they actually are. Tightness is just a sensation created by the nervous system.
Stretching to reduce injury
Improving flexibility to reduce the risk of getting hurt makes a lot of sense. Surely a short, tight muscle is more prone to injury than a longer, more flexible one?
Again, the research doesn’t back this up. As a 2002 editorial from the BMJ highlights, there’s no clear evidence that stretching before exercise reduces injuries.
And not to belabour the point, but remember that ‘short’ and ‘tight’ are sensations created by the nervous system, and don’t necessarily mean that your muscles are physically shortened.
Stretching and performance
Finally, what about the idea that stretching can help us perform better? The anti-stretching lobby pour scorn on this too, unless you’re taking part in a sport where flexibility is fundamental, such as gymnastics.
In fact, there’s a significant body of research that indicates that stretching before exercise not only doesn’t improve performance, but can actually have a negative impact on muscle strength and power.
In defence of stretching
More recently, a growing chorus of voices has begun to question our interpretation of the data, and to suggest that stretching is being unfairly vilified.
That the studies showing that pre-exercise stretching hurts performance were using protocols that don’t reflect a typical warm up: participants were asked to hold stretches for 60 seconds or more. Where stretches of less than a minute were used, there was no drop in performance.
That while it’s true that stretching doesn’t increase muscle length, our ligaments and tendons respond to tensile loads – i.e. pulling – by getting stronger.
And that although the increased range of motion resulting from stretching may be short term, it can still be beneficial for training effectively.
Can stretching make your ligaments loose?
Unlikely.
Just like muscles, ligaments and tendons return to their original length following a stretch. And as I’ve already mentioned, pulling on a ligament will tend to make it stronger, not weaker.
A common idea is that stretching triggers the stretch reflex, our nervous system’s protective mechanism that stops us tearing our muscles apart. And that repeated stretching somehow desensitizes this reflex, enabling us to pull our ligaments and connective tissues into ranges that are damaging. But there’s no hard evidence for this. And the stretch reflex tends to kick in when a muscle is significantly and rapidly lengthened, rather than when it’s slowly stretched.
My takeaway
For me, there’s currently no strong evidence that stretching is significantly beneficial, nor that it’s particularly damaging either.
So my takeaway is that if you’re struggling to find the time and/or motivation to stretch, don’t beat yourself up about it.
But equally, if stretching is something that you enjoy and feels good, keep doing what you’re doing. It’s unlikely to be doing you any harm.
A few final things to bear in mind.
Firstly, if you’re very flexible and tends towards hypermobility, stretching really isn’t your friend. Rather than passively hanging out at your end range, better to keep to smaller ranges of motion and stay active in your muscles. For example, instead of sinking deep into a lunge, imagine yourself lifting up out of it, to engage your leg muscles.
Secondly, the vast majority of research studies have been done on young, athletic populations. We really don’t know whether the results still hold for older, non-athletic bodies, or whether stretching may be more or less beneficial as you age.
And thirdly, stretching is not the only way to improve flexibility. Strength training, especially when done through a full range of motion, may even be more effective.
And if stretching, which is a relatively low load, can improve the strength of tendons and ligaments, resistance training will likely have an even greater benefit.
So whether you choose to stretch or not, make strength work part of your training programme.