• The Blog of Physical Therapist and Dancer Tony Ingram

  • Over 100 Articles and Blog Posts on Science, Training, Injuries and Dancing

  • Dance and Injury Prevention Workshops

  • Tony Ingram in 'Practice' dance video by Bold Creative

  • e-books: Common Injuries and their Recovery Explained Simply

Subscribe to BBoyScience by RSS! Connect with BBoyScience on LinkedIn! Watch BBoyScience on YouTube! Circle BBoyScience on Google Plus! Like BBoyScience on Facebook! Follow BBoyScience on Twitter!

Stretching improves strength. So?


People are getting a little too excited about a surprising new study that suggests stretching can improve strength.

Furthermore, it does so in both sides (more on the stretched side, though).

Since I know people (especially stretching enthusiasts) are probably going to take the results of this one study and run with them, I am going to write this quick article to throw a stick in their bicycle spokes.

Hopefully this gets around before it’s too late.

The results are not that surprising – and still don’t really support the use of stretching for anything other than specific flexibility goals.

The study in question:

This study was just published last month in the Journal of Strength and Conditioning Research 1. The researchers wondered if stretching a muscle on one side would have an effect on the other side.

Untrained individuals were divided into two groups: 13 of them in a ‘treatment’ (stretching) group, and 12 in a ‘control’ (do nothing) group. The ‘stretch group’ had to stretch their right calf under supervision (to ensure it was done right), for 30 seconds, 4 times, and with 30 second rests. They did this three times a week. They measured strength and range of motion (flexibility) in both sides before and after the study. The study lasted 10 weeks.

At the end of the study, the control group had no changes. The stretch group had an 8% increase in range of motion in the stretched calf… but the opposite side had a 1% decrease – which is kinda funny. However, the strength of the stretched calf increased by 29%, and the opposite side increased by 11% (a ‘cross-education effect’).


The researchers actually did this project to study the ‘cross-education’ effect (they make this somewhat clear in their introduction), which is indeed super-duper interesting – it’s not clear what causes this cross-over (which I’ve mentioned before here), so it’s a cool thing to study.

This study doesn’t suggest strength gains are ‘more’ of a neurological phenomenon than a morphological (size, shape, etc.) one. It’s already well known that strength increases have a neurological contribution, but changes in morphology are more important in the long run. 2

However, one thing that has gotten people so interested in this study is the finding that stretching lead to a significant increase in strength.

Why is this so interesting?

Well, those of us who are nerdy about exercise science know that stretching has gotten a lot of bad press. I myself have torn down stretching – quite a bit. Go to the ‘Exercise and Training’ section of this site, and scroll down to ‘Stretching’ to see my stretching articles.

Basically, yes, it’s good for increasing flexibility. Sport specific ‘dynamic’ stretching might prevent injuries and can help with some athletic tasks when performed as part of a warm-up. But overall, stretching doesn’t improve some important factors of sports performance (including strength), it doesn’t prevent injuries, and doesn’t significantly reduce post exercise soreness. Not a lot of bang for your buck!


But then along comes this study – apparently proving us all wrong about being less than impressed with the effects of stretching.

But here’s the thing about this study…

or… a few things…


When it comes to strength, a recent systematic review huh? did a ‘meta analysis’ on 104 studies on stretching and its effects on strength 3. It demonstrated that only a few studies ever showed an increase in strength after stretching, with the overall results typically showing a 5% decrease in strength with stretching greater than 45 seconds.

However, those are the immediate effects. Maybe stretching has different long term effects? I mean, if we studied a muscle immediately after resistance training, we wouldn’t be too surprised to find its strength severely diminished, would we? But we know that after recovery, the muscles will be stronger.

Muscles strengthen as an adaptation to applying tension, – causing micro damage, etc., etc. Stretching could certainly (and probably does) do that to a certain extent – it definitely applies a significant force to the muscle. Also, it should be noted that the stretch was performed using body-weight – the ‘curb’ stretch – like this, but with hands also against the wall. That’s not just a stretch guys.

Also, keep in mind that this new study used ‘untrained’ participants – which really means people who are not very physically active, if at all. Still, these were young (early 20’s) people, who were not necessarily ‘unhealthy’. Therefore, the slightest exercise stimulus is probably going to have a more pronounced effect on these people.

So, in physically sedentary (but young, and not necessarily unhealthy) people, applying tension (by stretching applied by body-weight, in this case) three times a week for 10 weeks improved strength in the muscles stretched.

So is this really that surprising? I think not.

Compared to what?

This brings us to another problem – compared to what?

The control group did -NOTHING- in fact, the researchers went to great lengths – making them keep a journal, and even checking sign-in sheets of local gyms – to make sure the study participants didn’t do any other physical exercise or stretching.

Although it’s interesting to see that stretching did do something – and this may lead to more interesting research in the future – this doesn’t give us much of a leg to stand on for making recommendations. For instance, how would this have been different if there were three groups? 1. stretching, 2. resistance exercise, and 3. controls.

Oh wait…

A study did exactly that last year 4

Researchers at the University of North Dakota published a study that had three groups of “untrained adults”: 1. full-range resistance training, 2. static stretching, and 3. a “do nothing” control group, and looked at the effects on flexibility and strength. For increasing flexibility, resistance training had roughly the same (if not greater) improvements in flexibility as the stretching group. For strength, yes, static stretching increased it. But not nearly as well as resistance training. Another interesting detail (although not “statistically significant” huh?) is that stretching increased strength in the quadriceps a little, but slightly decreased it in the hamstrings.

So there it is. Make of this what you will.


Let’s not forget that both these interesting studies were done on “untrained” individuals. Therefore, it’s very difficult to know how any of this stuff will affect people who exercise regularly, especially elite athletes. It’s very likely that stretching wouldn’t do a damn thing to increase strength in athletes. Furthermore, in people who need extreme flexibility in their sports – resistance training probably isn’t going to cut it. You still probably have to stretch your groin hard to get those splits.


The results of this new study STILL don’t imply that stretching:

  1. can replace strength training,
  2. prevents injuries, or
  3. is ‘necessary’ for anything other than increasing flexibility.

What is cool about this study is it adds to the idea that if you are inactive, doing anything will increase your general level of fitness – and hopefully health.

Stretching enthusiasts will take this new article and run with it – claiming how stretching does it all – and is good for your ‘holistic’ health. Whatever.

There are already many established benefits of strength training, and very few for stretching. So personally, if I had to choose one due to time constraints, it would be resistance exercise.

my crappy flares

However, I am currently stretching the hell out of my groin and hamstrings so I can do better flares in my b-boying. Because that’s what stretching is for. Flexibility.


Share the love!

    24 Responses to Stretching improves strength. So?

    1. Mary says:

      I think the point that the study was trying to excite the readers with was the fact that the effect, whatever it was, was contralateral.
      Also, the rebuttal article would be easier to read without the typos & grammatical errors…

      • Tony Ingram says:

        Hi Mary.
        In the first part: “the study in question” – after: “neato”, I describe exactly that – the purpose of the study. I know a lot of people are interested in the contra-lateral effect… that’s fine (even though it’s not really news). As (I think) I clearly stated, I wrote this article in the hopes it would keep people from getting too excited over the fact that stretching increased strength. I’m sorry I didn’t write that clearly enough for you.

        And I’d like you to point out some of these typos and grammatical errors, if you would be so kind. Spell check doesn’t catch ‘to’ vs. ‘too’, and what not. And in my defense, I wrote this article quickly because there are better things I can think of doing on my long weekend. Considering this, I’m pretty happy with my work.

        Anyone else find my article as difficult to read as Mary did?

    2. Scot Morrison says:

      Read fine for me.

      Good look at the study. Thanks for the thoughts. Just wait though, “strength stretch” classes will be popping up soon!

      • Tony Ingram says:

        Thanks Scot!
        And yes, haha “strength stretch”. Maybe even a new website – or book. And people will probably get stronger – ‘proving’ it works – and the most dramatic examples will be used in testimonials. A new therapy is born. :D

    3. Anoop says:

      Good one,Tony! And nice one about the comparison group. Most people miss who they compared it to. It is another great way to make your protocol look impressive.

      And I hear you about the errors. I get a lot of flak for it. The last thing I want to do after all the research and writing is to go though the article again to fix typos.

      • Tony Ingram says:

        Thanks Anoop! That’s right, it’s easy to have an impressive treatment effect when you compare something to nothing.

        And yeah, I’ll probably edit the article for typos and stuff. But not tonight!

    4. Tony Ingram says:

      Note to all: just fixed a few grammatical mistakes that my wife kindly pointed out. :)

    5. Vamshi Bhoi says:

      It’s good to be flexible,you know I do many kinds of stretches before practice in my opinion stretching makes you feel confident that you will not screw yourself when practicing n doing hard moves that need flexibility,good article!!!:)

      • Tony Ingram says:

        Woah, can’t believe I never saw this comment before! You’re right Vamshi! Stretching still has value. I certainly feel better stretching before practice, and I’m sure it prevents some strains in activities requiring lots of flexibility, like dancing.

        I just write articles like this because it’s important that people don’t get carried away with the benefits of stretching. They might miss other important things!

        Thanks for the comment!

    6. Rolf-Inge Nodberg says:

      Does anybody know how the streching was done?

      • Tony Ingram says:

        GREAT question. Just read the paper again, and added to the article above, under the heading strength. They did the ‘curb’ stretch.

        Not only was it a stretch – it was weight bearing with body weight… again, in untrained individuals – it’s no wonder they gained strength.

        The contra-lateral effects are a little less impressive too, because they had to bear some weight on the left leg to sustain the stretch.

    7. Paul says:

      As far as I know – the greater the angle being strained, the less strength; the smaller the angle of strain, the more strength is exerted by the muscle. If stretching increases flexibility and strength was measured at full range of motion of the newly stretched muscle – shouldn’t it have less strength overall (due to the weaker angles being applied)?

      • Tony Ingram says:

        Hi Paul,
        In this study, strength was measured with a 1RM standing toe raise on a smith machine – not isometrically at end range. Stretching was measured in a kinda funny way – standing squat with one foot roughly 2 feet behind (the rear foot was measured); basically, a standing soleus stretch. If they measured strength in the end range, then you are right – it’s probably weaker as the muscle will be at a mechanical disadvantage. But that’s not how they measured outcomes in this study.

    8. Etrigan says:

      You just don’t want to admit that you were wrong. Like most people you are to proud to say those words, “I was wrong” so instead you write this tortuous article trying to justify your erroneous positions.

      It is absolutely ridiculous to say stretching doesn’t decrease the risk of injury. Try doing high kicks with cold muscles without stretching, and see what happens to your hamstrings. Talk to gymnasts, martial artists or cheerleaders and ask them whether stretching decreases the risk of injury.

      Don’t deny science just to protect your ego and seem consistent. Stretching is extremely beneficial for so many reasons I won;t bother to enumerate. But if you open your mind to findings like these, it will be the first step to our own education.

      Delete all those wrong anti-stretching articles and start over.

    9. Neil Keleher says:

      In one of your comments above you talk about the curb stretch as unusual because it uses body weight. I do all of my stretching (most of it anyway) using body weight. Makes it easier to relax the muscle being stretched. But I can also activate the muscle being stretched also (I think of this as resisted stretching.)

      It’s not written up in any literature (that I am aware of) and personally I don’t read much about stretching because I go by experience and what works, but I’d agree with the comment etrigan made, it is kind of hard to do a high kick unless you are flexible.

      How many people actually do stretch for injury prevention as opposed to stretching just to get flexible (so that we can do more things with our body?) You’ve said it yourself, you aren’t “anti-stretching” but it can come across that way since you focus a lot on what stretching isn’t instead of what it is.

      Be interested in seeing how you are working on side splits by the way.

      • Tony Ingram says:

        Hi Neil,

        I agree that many great stretches involve using your bodyweight – I am working on splits (admittedly very inconsistently) through this method. Hard to describe here. Anyway, I didn’t say this stretch was ‘unusual’ – I just pointed out that the strengthening effects cannot be purely attributed to the “stretch”, because there was also some bodyweight resistance applied to the muscle, which would be expected to cause strengthening.

        Personally, I read a lot of the literature because 1. I am interested in how things work, and 2. going by experience and what “works” is usually very misleading. Of course doing a high kick would be difficult without the necessary flexibility – this is exactly what I say in pretty much all of my stretching articles.

        I am not anti-stretching, but I am anti-stretching-as-injury-prevention, because it’s not effective for most sports (I admit, it may be for some things, like dancing). People should be focusing on other things, like neuromuscular training for coordination.

        I hope this cleared some things up.


        • Etrigan says:

          “I am not anti-stretching, but I am anti-stretching-as-injury-prevention”

          The more you comment the sillier you look, and the clearer it is that you’re just a troll revelling in the attention. Like I said, get out of bed first thing in the morning, and do a Karate high kick or cheerleader full split without stretching. When you get back from the emergency room, come tell me again that stretching doesn’t prevent injury.

          “because it’s not effective for most sports (I admit, it may be for some things, like dancing).”

          Oh, you ADMIT! How gracious of you. Now you’re contradicting yourself. It’s not effective, but it’s effective. which is it? Muscles don’t know the difference between sports. They’re either protected by stretching or they’re not.

          Dude. The study you cite proves you’re wrong. There are a hundred proving you’re wrong. Anybody who actually does kinetic sports knows you’re wrong. I’ve been doing martial arts and yoga for over 20 years, and I know you’re wrong.

          Enjoy your trolling and responses. You seem to enjoy the attention. This is just a message for anyone reading this blog to get information: please ignore this guy. He’s not a scientist, just a troll who would rather split hairs endlessly than say “I was wrong.”

          • Tony Ingram says:

            Wow. What are you so angry about?

            The more you comment the sillier you look, and the clearer it is that you’re just a troll revelling in the attention.


            Like I said, get out of bed first thing in the morning, and do a Karate high kick or cheerleader full split without stretching.

            When did I say you should do something like that without warming up?

            Muscles don’t know the difference between sports. They’re either protected by stretching or they’re not.

            You’re right, the muscles don’t know. But different sports place different demands on the body and the risk of overstretching is much more likely in something like dance, or martial arts, or gymnastics. Did you see my other article “stretching for dancers?” I thought I was clear on this.

            Dude. The study you cite proves you’re wrong. There are a hundred proving you’re wrong.

            Would you mind citing a few of these studies? Sounds like they are not hard to find.

            Meanwhile research keeps piling up that stretching is generally ineffective for preventing injuries, for most sports. I’ve cited plenty of studies. Here’s another review article: http://bjsm.bmj.com/content/48/4/287.full.pdf+html Here’s another: http://www.ncbi.nlm.nih.gov/pubmed/24100287 . The second one I blogged about recently, and I was actually pretty defensive of stretching, because I actually think more research needs to be done before it is ruled out for activities that require large ranges of motion.

            I’ve also thought about going back and changing all my old blog posts on the matter, making them less black and white. I agree that this particular blog post itself was a little too negative, but I stand by the points I make.

            Anybody who actually does kinetic sports knows you’re wrong. I’ve been doing martial arts and yoga for over 20 years, and I know you’re wrong.

            I guess you haven’t read much else I have written, or you would know how useless your anecdote is in proving a point. Your experience and intuition doesn’t beat carefully controlled research involving thousands of people.

            Enjoy your trolling and responses. You seem to enjoy the attention. This is just a message for anyone reading this blog to get information: please ignore this guy. He’s not a scientist, just a troll who would rather split hairs endlessly than say “I was wrong.”

            I am not sure how you would define “scientist”, but I am indexed in pubmed and am starting my PhD in Neuroscience this September. I’m also a licensed physical therapist with experience in treating sports injuries. I’m not trying to brag, but defend myself here. And it doesn’t matter who/what I am, I’ve cited research and tried to reason carefully to support my arguments — that’s what should matter here. Interestingly, however, you’ve done neither, and haven’t cared to identify exactly who you are either.

            And in fact I do believe I am wrong about a lot of things…

            Over the last year, I’ve almost completely stopped blogging. Why? I’ve gotten the attention you say I love. Well I don’t. I recognize it as a responsibility, and it prompted me to keep digging deeper into the research, science, and philosophy in general. I’m less certain than I have ever been, but I really enjoy research so that’s where I am headed with my career. I’m not sure what I’m going to do with this blog, but one thing is for sure: I’m not afraid to admit I am wrong.

            Not sure what else to say.

          • Scot says:

            Not even a good attempt at trolling here E. Try a less emotional approach an mix something besides anecdotes with your analogies to get a post that actually warrants a good solid response. This will allow for more enjoyable trolling on sites outside of bodybuilding.com or Tnation.

    10. I did read somewhere that most sprains are caused by movement way beyond the normal ROM, and considering that, it is clear that stretching could *not* have prevented those.

      But I wonder, have any studies been done where athletes, dancers or martial artists have done high-speed flexibility moves without a warm-up? That would be the only way to realistically test the hypothesis that stretching can prevent *some* injuries, most likely minor muscle strains, I would expect.

      • Tony Ingram says:

        True, most studies on stretching an injury prevention are done on runners and soccer players, at least that I’ve read. The McHugh review article (2010) does support stretching to prevent strains a little (although the evidence is slim). Personally, I think it does help. But stretchings role in injury prevention pales in comparison to neuromuscular / motor control / coordination type training.

        Interestingly, I read one study on middle aged martial artists (reference) that showed static stretching as not to impair performance, which led the authors to speculate that stretching is fine in most people, especially people who may be “stiffer”, and that we shouldn’t generalize the research that’s typically done on young varsity athletes (which is most research on stretching, or exercise science, period).

    11. Hannu says:

      I’m looking for information about chronic stretching AFTER strength exercise. It might have two effects – micro tears on muscle and improve blood flow due to relaxing stretched muscle.

    12. Josh Vogel says:

      Hi Tony,

      Great article. Thanks for sharing this information! I’m curious, have you had any experience or done any research on Progressive Loaded Stretching? As far as I understand, it’s using bodyweight or other external resistance to stretch but also strengthen through the entire range of motion of the stretch.

      Here’s a Reddit discussion that may describe it better than I can:


      Any thoughts or information you feel like sharing would be much appreciated.



    Leave a reply