Stretching DOESN'T lengthen muscles!

​In this next article in our stretch series, I am going to be looking at whether stretching actually increases the length of our muscles and makes us more flexible like we all believe. It’s commonly believed that if we stretch (especially after exercises) we are increasing the length of our muscles which will increase our flexibility and will help prevent injury & muscle soreness (DOMS). The latest research has shown that this is probably not the case. 

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In this next article in our stretch series, I am going to be looking at whether stretching actually increases the length of our muscles and makes us more flexible like we all believe. It’s commonly believed that if we stretch (especially after exercises) we are increasing the length of our muscles which will increase our flexibility and will help prevent injury & muscle soreness (DOMS). The latest research has shown that this is probably not the case.
 
As I have mentioned before stretching is one those unquestionable beliefs that have been installed in us since of early days of PE at school. It was a bit of given. We need to stretch off after exercise so that our muscles don’t ‘shorten’ up and we don’t get injured. That belief has been carried forward, and we see stretching everywhere now, whether it’s at the end of an exercise class, Joe Wicks’s latest workout video on Facebook (along with lots of other trainers sharing video’s on Facebook) or even in Therapy environment where people are trying to get themselves out of pain.
 
But can we actually increase the length of our muscles and improve our flexibility through stretching?
 
Let’s have a look at some research into this. I have purposely kept these brief to make them easy to understand, however I have included the full links at the bottom should you wish to read any of the research in full.
 

1. The first piece of research was looking at the “effect of a long-term stretching regime on the tissue properties and stretch tolerance of human skeletal muscle”. This research found the tolerance to the stretch was increased (a bigger stretch could be handled more), however the muscles did not increase in length.
2. In this research the group stretched one leg over 4 weeks and did not stretch the over, so to compare the difference between the two. Ultrasound was used to look at the thickness of muscles before and after. The research found “muscle viscoelastic properties and strength were preserved despite improved straight leg raise”, so the muscle didn’t change but there was a little more movement in the straight leg test.
3. Here the research was carried out over 3 weeks, with 1 minute hamstring stretch for those with musculoskeletal pain. The research showed “stretch did not increase muscle extensibility”.

 
You can read the research in full in the sections below.
 
So the research shows at that we can increase tolerance to stretching (we can go further after each stretch) but it shows it doesn’t make our muscles ‘longer’. It is also questionable if we actually need to increase our tolerance to stretch.
 
There is probably many factors as to why movement increased slightly, but we know the muscles didn’t change in length.
 
The research also doesn’t show any improvements to flexibility with stretching. If you are stretching to improve flexibility the main question we should be asking ourselves should be “how flexible do we need to be”, otherwise we just aimlessly trying to improve flexibility with no end goal in sight (I’ll make a separate article for this subject).
 
Does this mean we shouldn’t stretch?
Not necessarily. Do you like stretching? Does it feel good for you? If the answer is yes then by all means keep stretching (I rarely recommend to not do something if it feels good). Are we just stretching because we think its going stop us getting injured, stop us feeling aching the next day or make our muscles longer? If that is the only reason your stretching then you probably need to do something more effective.

Sources
Magnusson SP, SImonsen EB, Aagaard P, Sorensen H, Kjaer M, 15 Dec 96, A mechanism for altered flexibility in human skeletal muscles, available at www.ncbi.nlm.nih.gov/pubmed/8951730/, Accessed 01/02/19

Yilnen J, Kankainen T, Kautkainen H, Rezasoltani A, Kauukkanen T, Hakkinen A, Jan 2009, Effect of stretching on hamstring muscle compliance, available at https://www.ncbi.nlm.nih.gov/pubmed/19197574/, Accessed 01/02/19

Law RY, Harvey LA, Nicholas MK, Tonkin L, De Sousa M, Finniss DG, October 2009, Stretch exercises increase tolerance to stretch in patients with chronic musculoskeletal pain: a randomized control trial, available at https://www.ncbi.nlm.nih.gov/pubmed/19696119/, Accessed 01/02/19

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About the author
I am a Manual Therapist covering a range of different disciplines including massage & Biomechanics. I also run small specialist Pilates classes around Corfe Mullen, Broadstone, Wareham, Wimborne & Poole. Instead of just purely rubbing the pain, I always look to see if I can find a potential cause (or causes of the pain) and then work on treating this