How Important is Stretching?

7/10/2021

Often when I’m talking to my patient about their injury and why it has happened, they guiltily report that they don’t stretch enough.

We’ve all grown up being told how important is it to stretch:

to warm up
to cool down
to prevent injury
to help muscle soreness
to improve flexibility
to improve performance

I’d guess that most people feel guilty about not stretching enough.

Interestingly, health professionals have changed our tune about the importance of stretching. Research over the last 15 years has suggested static stretching is not as beneficial as was once thought. I’ve been having conversations about the reasons to stretch (or not) for at least the last 15 years, but the current science on stretching just isn’t catching on.

So, what do we know?…

DOES STRETCHING PREVENT INJURIES?

No. There is a lot of evidence that stretching does not reduce the risk of injury. This systematic review and meta-analysis of randomised controlled trials found stretching does not prevent injuries, whether done before or after training. This randomised controlled trial, and this systematic review concluded stretching before exercising only reduces the risk of injury by less than 1%.

Therefore, in practical terms the average athlete would need to stretch for 23 years to prevent one injury. Definitely not worth it.

DOES STRETCHING HELP MUSCLE SORENESS?

No. A systematic review concluded that stretching before or after exercising does not confer protection from muscle soreness (ref). Stretching was found to reduce muscle soreness by a trivially small amount - less than 2%.

“Most athletes will consider effects of this magnitude too small to make stretching to prevent later muscle soreness worthwhile.”

DOES STRETCHING INCREASE RANGE OF MOVEMENT?

No. Stretching for the amount of time that most people would hold their stretches, does not make any actual difference to flexibility. The mechanisms of stretching have been extensively studied. There is moderate evidence from a systematic review that stretching can increase flexibility (ref). However, to achieve an actual improvement in muscle compliance we know the total duration of stretching needs to be at least five minutes per muscle group (ref). Therefore to stretch hamstrings, quads, and calves, both left and right, as part of a warm up before sport, it should take at least 30 minutes - which is practically impossible as part of a warm up. We know the one or two, thirty second stretches the majority of athletes would perform during their warm up are just not enough to actually improve their flexibility (ref).

DOES STRETCHING HELP PERFORMANCE?

What people find most surprising about static stretching is it impairs subsequent performance (ref).

A substantial body of research has shown that sustained static stretching acutely decreases muscle strength and power (ref). Stretching before an endurance event lowers endurance performance and increases the energy cost of running (ref). Cycling efficiency and time to exhaustion are reduced after static stretching (ref).

Pretty much any measure of performance is made worse by stretching. Static stretching impairs:

strength
maximal voluntary contraction
isometric force
isokinetic torque
one repetition maximum lifts
power
vertical jump
sprint times
running economy
agility
balance

A comprehensive review (ref) from 2011 concludes:

“Based on the majority of the literature, it would seem logical to recommend that prolonged static stretching not be performed prior to a high level or competitive athletic or training performance.”

WHAT ABOUT DYNAMIC STRETCHING?

Obviously, I’ve been talking about sustained, static stretching. It has been shown that there is no stretch-induced strength loss with dynamic stretching (ref). However, the efficacy of dynamic stretching for increasing flexibility is yet to be determined (ref).

SO WHY STRETCH?

I do get people to stretch if there’s a specific pathology that needs treating. And you do need to stretch if you need flexibility to achieve certain positions in your sporting performance (hurdlers / gymnasts / divers, etc).

SO SHOULD WE STOP STRETCHING?

If you’re happy with your stretching routine, keep doing it. If you think it feels good to stretch after exercise then there’s no harm. But I definitely wouldn’t recommend stretching at the expense of other techniques that are proven to aid recovery.

Do you love a good stretch?
Or feel guilty you're not stretching enough?...

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