• 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!

The Problem with ‘Types’ of Stretching – Part II

bboy-specific quadriceps stretching?

When researchers began to show that stretching isn’t as great as once thought, the knee-jerk reaction from the health and fitness community (or should we say: industry) was:

“well… obviously it’s because people are stretching wrong!”

This spawned tons of magazine and website articles from ‘gurus’ who proclaimed that the ‘right’ way to stretch wasn’t ‘static’ stretching, but ‘dynamic’ or ‘active’ stretching.

But are these other methods really any better?

In Part I we reviewed the different types of stretching.

In Part II, we’ll review what the research is telling us so far. Finally, we’ll outline some recommendations you can start using NOW to take advantage of the ‘pros’, while avoiding the ‘cons’!


For a review on the pros and cons of stretching, read: Stretching. In summary:
1. stretching does improve flexibility,
2. does not improve athletic performance,
3. does not prevent injuries, and
4. stretching can even temporarily reduce strength.

Most of that research has been done on ‘static’ stretching.

But are different ‘types’ any better?

Skip to the bottom summary if you just want a short answer.

For those interested in detail, let’s look at the research:


IMPROVING FLEXIBILITY:

For the goal of improving range of motion, research results are mixed. In many cases, results favor typically ‘Passive-Static’ stretching for improving range of motion 1, 2, 3, 4, 5, 6. Still, a few studies do favor active methods 7, 8. Effect sizes huh? almost always look small, meaning the differences are never that big in any of the studies. Based on this review, the overall difference between methods isn’t much to get excited about!

Bottom line: other types of stretching are not really any better!

In fact, classic static stretching might be the best way to improve flexibility.

But why not? If active/dynamic methods are more “functional” (meaning they mimic actual athletic performance more) then why aren’t they any better than plain old static stretching?

Here are some possible reasons for each type:

Active stretching:  Active stretching may not actually cause much of a ‘stretch’. Even if a muscle is strong enough to lift a limb all the way (to stretch the opposite muscle), it can still be limited by other factors. Muscles can only contract (shorten) so much, and once they bunch up, they can’t go any further. Then there is ‘active insufficiency’ which means once a muscle is shortened so far at one joint, it can’t produce enough force to shorten all the way at another joint here’s an example. It’s possible to reach this point in the agonist (contracting muscles) before a good stretch is obtained in the antagonist (opposite muscle).

Dynamic stretching: Flexibility is more of a neurological adaptation: flexibility seems to increase because people tolerate stretching better… not because the muscle actually gets longer or more extensible 9. Since dynamic stretches are constantly moving, they probably don’t allow for enough time in the ‘stretched’ position (the end range of motion) to allow for much of an adaptation. Same issue with ballistic stretching: and research backs this: a study found static stretching improves range of motion better than ballistic 10.

PNF stretching: This kind of stretching works by temporarily decreasing the normal reflexive tightening of your muscles when they detect a stretch. But if increasing flexibility is a matter of improving your ‘stretch tolerance’, than is this just making it easier to tolerate at the moment, but no better in the long run? This may be similar to how NSAID’s work to decrease muscle soreness, but can harm exercise gains because the inflammation is key for muscle repair. Bottom line: making things easier usually doesn’t help. It’s supposed to be a bit uncomfortable. It’s supposed to be difficult. No short cuts!

Static stretching: Seems best for improving range of motion. This is because you actually hold the end range for a period of time… a good idea if what you are trying to do is improve your ‘stretch tolerance’.

But no one ever said stretching didn’t work. It’s been known for ages to be good for improving flexibility. The problem was with athletic performance and injury prevention.

So what about those things?

Let’s move on!


ATHLETIC PERFORMANCE:

Good news, everyone!

For athletic performance, however, dynamic stretching may actually help! Using dynamic stretching as part of a warm up seems to improve sports performance 11, improve agility 12, and improve muscular power 13,14.

This actually makes some sense. Dynamic stretching looks more like a warm up than an actual stretch. And we already knew warm-ups are helpful for sports performance, and possibly for preventing injuries.

Furthermore, it may be exactly how we should be warming up. Dynamic stretching even seems to be better than a simple jog 15, as it brings you through your full range of motion in a variety of movements. The key is to cover as much range as possible, in many different ways, preferably using movements similar to the activity you are warming up for.

It should be emphasized that it is dynamic stretching, not the other types, for which these results were found. Dynamic stretching is almost always ‘active’, not ‘passive’.

Okay, that’s cool! So what about injuries?


INJURY PREVENTION:

Finally, the biggest problem of all:

Lack of flexibility is not why injuries happen…

Muscles tend to get injured during eccentric contractions (like lowering a weight instead of picking it up) within a muscles normal range of motion 16. You’re more likely to hurt yourself with a big forceful movement or a quick switch in direction. The reason ‘over-extending’ yourself can cause strains is the same: the tremendous force this imparts on the muscle while it eccentrically contracts to resist. If no muscles were active, you would probably get a ligament sprain rather than a muscle strain.

For more information on how most injuries happen, read: How Injuries Happen.

So it does not matter how someone stretches… flexibility isn’t the problem!


SUMMARY

  • For increasing flexibility, good old ‘static’ stretching seems to be the best. But because it temporarily decreases strength, stretch after exercise.
  • For improving athletic performance, it seems a warm up with dynamic stretching might actually be helpful before exercise.
  • For preventing injuries… no type of stretching will help. Just warm up, do things right, and be careful!

RECOMMENDATIONS:

To take advantage of the ‘pros’ of stretching, while avoiding as many ‘cons’ as you can:

1. Warm-up (raise your temperature and sweat a little) and include simple, sport-specific, ‘dynamic’ stretches. ‘Static’ stretches should be limited to 15-30 second holds, once per position. Warm-up for 10-15 minutes, or until you feel ready to rock.

2. Exercise / Compete / Perform / Practice… do your thing!

3. Lots of ‘Static’ stretching afterwards to improve flexibility, if you need to. Hold sport specific positions at the end range (avoid pain) for about a minute, repeating 2-3 times.


That’s it!

Next article about stretching will FINALLY be a HOW-TO article.

Hope this information cleared up a LOT of confusion.

Good luck!

Share the love!

    7 Responses to The Problem with ‘Types’ of Stretching – Part II

    1. This was good, and I agree with most of what these two articles state. I am however a little sceptical of two things:

      1) You imply, albeit with a question mark at the end, that PNF is less effective because it’s due to temporary neural adaptations. I don’t think you can back that hypothesis up with any existing data, and I doubt you’re right as all stretching methods really for the most part come down to neural adaptations anyway. Still it would be interesting to test chronic effects of PNF vs. other types of stretches to see if you’re onto something. Most coaches will not hesitate to say that PNF is more effective than a regular passive stretch, but who knows, maybe we’re just parroting each other. In which case we need to figure this out empirically. However until PNF is proven less effective I think I’ll choose to keep using it. My experience is that it works rather well.

      2) As for injury prevention, I agree that injury in the muscle tissue or surrounding fascia of a given muscle is probably not prevented by increasing the flexibility of the muscle that is put under strain, although I do believe there still exists some uncertainties regarding this. Lack of flexibility could however lead to a whole host of other types of injuries. One example would be when tight hamstrings and/or hip external rotators cause lumbar flexion in the spine during squats. We all know this can lead to disc herniation. When normal ROM is restricted compensation in movement patterns will inevitably occur, placing undue stress on other structures of the body. Saying that stretching does not prevent injury is therefore only true in a very narrow sense.

      • Tony Ingram says:

        1. “I don’t think you can back that hypothesis up with any existing data, and I doubt you’re right as all stretching methods really for the most part come down to neural adaptations anyway.”

        I’m glad you recognized that I am just postulating here, and do not claim to have ‘the’ answer. Still, I’d argue that my stance is based on known evidence. So let me explain:

        First, I need clarification – are you saying I can’t back up the fact that stretching involves a neurological adaptation? Or that PNF isn’t really better in the long run? I’ll respond to both assertions either way.

        For the neurological effect, here’s some evidence: 1 , 2 , 3.
        And I also have some evidence that neurophysiological adaptations are very short lived – such as in spinal manipulation (5 minutes): 4.
        And for PNF specifically, it seems the previously believed ‘reflex’ mechanisms are not responsible for it’s success 5, but rather, it’s the alteration of ‘stretch perception’ 6.

        Now, about the effectiveness of PNF in the long run, I’ll move on to your next comment:

        “Still it would be interesting to test chronic effects of PNF vs. other types of stretches to see if you’re onto something.”

        The only two studies I could find at the moment suggests static stretching is better for increasing range of motion. A four week trial : 7 – and six weeks: 8 Maybe you don’t consider 4-6 weeks ‘chronic’, but I believe it reflects real life program adherence quite well.

        “Most coaches will not hesitate to say that PNF is more effective than a regular passive stretch”

        Probably because it does have a strong immediate effect. I’m not in the mood to find research on that point – you probably agree with me anyway.

        “However until PNF is proven less effective I think I’ll choose to keep using it. My experience is that it works rather well.”

        All I have to say to that is: 9 – and for exercise specifically: 10.

        2. “Lack of flexibility could however lead to a whole host of other types of injuries.”

        Not according to the literature I’ve reviewed – and described in a few articles now. Can you show me some evidence otherwise?

        “One example would be when tight hamstrings and/or hip external rotators cause lumbar flexion in the spine during squats. We all know this can lead to disc herniation.”

        Can you provide some evidence for that please? I’d love to review it.

        “When normal ROM is restricted compensation in movement patterns will inevitably occur, placing undue stress on other structures of the body.”

        Sounds like the ‘Functional Movement Screen’ stuff. Is this where you are coming from?
        Compensation is quite normal, and one of the ways we learn to move in interesting ways, and adapt to different situations with high fidelity. If you are talking about heavy load exercise (weight lifting, power lifting), I might agree with you – but if we’re talking about anything less intense, then I would disagree that it is relevant.

        “Saying that stretching does not prevent injury is therefore only true in a very narrow sense.”

        Narrow? I think I’ve provided plenty of evidence that stretching is ineffective for preventing injury in a very broad sense. Even for athletes requiring excessive flexibility – like dancers (I wrote an article on that too).

        Again, I feel like I have to say, once more, that I am not saying “don’t stretch”. I stretch a lot to dance the way I want to. But I don’t do it thinking it’s going to keep me from injuring myself.

    2. [quote]First, I need clarification – are you saying I can’t back up the fact that stretching involves a neurological adaptation?[/quote]

      No. How did you arrive at that conclusion? I said that the effect of any stretching technique is largely neural, PNF included, which is why I don’t buy the idea that it’s any less effective. I believe Pavel Tsatsouline referred to a Russian study on PNF in “Relax into Stretch” where he states that it’s 267% more effective than a static stretch, but I don’t have the book now, and of course I never saw this study, so it’s hard for me to check the assertion and its source.

      Yes, I do come from an FMS standpoint, but I admit I also tend to think of training in terms of heavy loaded exercises as I am also into powerlifting, so it didn’t really occur to me that you might be talking about movement without external resistance. However having said that, Gray Cook, whom I hold in high esteem, seems to a disagree with you. He basically says that any faulty movement pattern will create problems when you train it with quantity. You may not notice your hip stability problem or whatever else is off the mark, but do long distance running long enough, and presto, you get some sort of injury up or down the kinetic chain. You can choose to disagree of course, but I think his arguments are pretty solid.

      It’s hard to produce a controlled study that would show that lumbar flexion in the squat could cause injury, as this clearly would be unethical to test, but I think Stuart McGill has shown pretty clearly that loaded movement in lumbar flexion causes injury over time, and there are plenty of injuries happening at gyms all over the world that would substantiate the claim. Furthermore it stands to reason that large sheer forces on the spine are dangerous. Any structure subject to external forces has it’s breaking point. This problem will of course more easily occur for people who lack proper hip or ankle mobility, especially when they attempt to go to what would otherwise be considered proper depth. If the lack of mobility was caused by poor flexibility, wouldn’t stretching have prevented injury in such cases? I sure as hell wold not risk doing my max effort squat session this week if I experienced a noticeable loss of hip mobility when warming up.

      • Tony Ingram says:

        PNF: I’d love to see the study that claimed PNF to be so superior, but without it, I have to go by the more recent research I’ve posted here.

        I’ve skimmed Pavels book on stretching: https://www.msu.edu/~gilber96/pavel.pdf
        He mentions that same ridiculous number – with no reference of an experiment! There isn’t any references at all in this book. He talks about the science of PNF stretching – which has been proven wrong!

        FMS: Not that there is no value to FMS, but food for thought: Subscribing to FMS isn’t exactly evidence-based, no matter how logical it seems. I’m not going to pick apart the faulty lines of reasoning in this trendy program – I’ll just post another blog that did it pretty well already: http://saveyourself.ca/articles/functional-movement-screen.php

        SQUAT: Yes, I’m talking about any athletic activity, not just heavy lifting. I think it’s obvious that if you need flexibility (as required for a full squat) then you should stretch to get it. That’s where stretching obviously has it’s value – flexibility. But if you can already do it – then added stretching isn’t going to prevent injury, even for heavy lifting. That’s what we are talking about here: stretching as an injury prevention modality itself – which the research clearly indicates is ineffective.

        Thanks for the reference on the McGill work (which I am aware of – I took a course from him a couple years ago). I’d like to point out that this is an in vitro study. It’s results are interesting, but cannot be generalized – not even close – to asserting that stretching is necessary to prevent back injury in squats! Because we are talking about stretching here, right? Your comment: “This problem will of course more easily occur for people who lack proper hip or ankle mobility…” is a GIANT leap in reasoning, and itself requires research to substantiate.

        Christer, I’d enjoy this discussion more if you didn’t simply “name-drop” in each paragraph of your response without actually providing any primary sources for your assertions (which you’ve only done once – and it was quite a reach to make your point).

        It’s not hard to sift through pubmed or google scholar to find good sources to back up your points – if they exist. I carefully take my time to do this every time I write an article, and usually when I comment too. If you are going to keep making comments, I’d appreciate the same effort from you. If we’re going to discuss science, please stop simply posting your assumptions, or ‘guru’ advice.

    3. In case you wanted a reference to a McGill study. It’s not on the human spine of course, but I think it gives us reason enough to be very cautious:

      Callaghan*, J.P., and McGill, S.M. (2001) Intervertebral disc herniation: Studies on a porcine model exposed to highly repetitive flexion/extension motion with compressive force. Clin. Biom. 16(1): 28-37.

    4. Okay. I see you’re going to stick to your guns on this, and on some points I think we just have to agree to disagree. In real life practice I for instance find tremendous value in the FMS screen when I work with clients, not least because it tells me quite clearly what I should not do to maximize safety when choosing exercises for a fitness program. Do no harm will always be an important motto for me.

      You may be right about Pavel though. It has been a long time since I read that book. I just wanted to mention that there might be some old Soviet science on this that isn’t published on the net. I admit that I have not seen it, and I’m sorry I mentioned Pavel if he didn’t refer to it properly.

      As for the squat I was not saying that stretching is necessary if proper mobility is already present. Rest assured we both agree that this is useless.

      You make some assumptions about what I try to say that are not true. As I said in my first post, we agree on almost everything when it comes to stretching, so please don’t make me sound like an idiot who ignores science just because I didn’t bother to dig around Ergo-log and Pubmed to support every sentence I wrote.

      When it comes to the squat I was merely stating that working under load with lumbar flexion increases the risk of injury, and you will end up in flexion when hip and/or ankle mobility decreases.

      My last assertion is an observable fact. Take any guy with hip or ankle restrictions and have him perfom a squat below parallel and he will go into flexion involuntarily. You don’t need a study to confirm that. It happens every time. His pelvis must tilt. It’s a basic law of anatomy, and not a giant leap at all. Hell, I see it virtually every day at work. Now, maybe we should have a study that shows that placing a heavy load on such a guy’s back will also cause injury, but is it really necessary? If you think it’s harmless by all means give it a try, but there are countless people outside of studies who have gotten injured this way. Do you really want to disregard that?

      I think I’ll leave at that.

      Thanks for the articles by the way. You are indeed very knowledgeable, and a good writer as well. :-)

      • Tony Ingram says:

        Christer,

        Thank you for the kind comments about my writing. Sorry for being strong headed and sounding mean – certainly not trying to come off that way. I’m just trying my best to keep the content of this site as evidence-based as possible, but I probably should ease up when it comes to comments.

        About the squats, my instincts are definitely in agreement with yours in that the most mechanically advantaged/ergonomic/”correct” form is necessary for heavy lifting (especially squats and deadlifts). Perhaps a lack of mobility would alter form, certainly. What I meant by a leap in reasoning is using the McGill study to substantiate that. Either way, I agree that to attempt such an exercise with an extreme range of motion, one should ensure enough flexibility. That’s a very indirect way stretching may prevent injury – but a way none-the-less. Therefore, going back to the last sentence of your original post: “Saying that stretching does not prevent injury is therefore only true in a very narrow sense.” – I’d say it’s the other way around. In general, stretching before exercise is not a good way to prevent injuries. But of course, we can agree to disagree :)

        Either way, you’re right – I would never have someone do a full squat under a heavy load unless they had the proper hip mobility! And on a personal note – I think everyone should be able to do a full squat if they want to be an athletic person!

        Thanks for the interesting conversation – it allowed me to summarize and revise some of my thoughts on the nuances of this subject. I believe we’re somewhat on the same page now. Hope you stay in touch!

        Cheers!

        Tony

    Leave a reply