Does Excessive Sitting Shorten the Hip Flexors?

Sit In

Time for hip flexor stretches?

Excessive sitting will shorten your hip flexors. I have read this sentence many times. What I have never read is a citation to supporting evidence at the end of the sentence. It’s one of those claims that no one ever questions, like you should drink eight glasses of water a day. Let’s see how it stands up to some critical inquiry.

How might we test the hypothesis that sitting will shorten the hip flexors? I can think of three ways. If the hypothesis were true, we would predict that: (1) there would be a correlation between time spent sitting and hip flexor length; (2) there is a plausible physiological process for how sitting would shorten the hip flexors; and (3) healthy animals engaged in natural functions would avoid placing their joints in shortened positions for long periods of time, like we see in sitting. Let’s examine these predictions in turn.

1. Studies on sitting and hip flexor length

Are there any studies that find a correlation between length of time sitting in a chair and hip flexor tightness? Searches on google scholar and pubmed turn up nothing. Strike one, but absence of evidence is not evidence of absence. So let’s move on.

2. What is the Mechanism?

Is there any plausible physiological process that could explain how excessive sitting could shorten the hip flexors? It is well known that completely immobilizing a joint for an extended period of time can lead to loss of muscle sarcomeres and contracture and cross linking of connective tissue. However, it appears that one can fully prevent any negative effects of extended immobilization on tissue length with only short and infrequent bouts of movement. In one study, researchers kept the soleus muscle of a rat completely immobilized in a cast for 10 days. Every two days the cast was removed and the muscle was stretched for fifteen minutes. This was enough to preserve tissue length, but not enough to make the rat happy with the experiment. (Williams, 1988).

In another study, just half an hour of stretch a day preserved range of motion and muscle length in a muscle that was immobilized in a shortened position for the the rest of the day. These studies suggest that sitting in a chair almost all day every day would not cause loss of tissue length, provided you get up to go the refrigerator every once in a while. Strike two.

3. Is it “natural” to keep the hips flexed for long periods of time?

If sitting in a chair many hours a day leads to shortened hip flexors, we might predict that it is generally unhealthy to hold the joints in one place for a long period of time, and that healthy animals engaged in natural behaviors would avoid this. But this does not appear to be the case. It is easy to think of examples of animals who hold static limb positions for long periods of time without loss of function. Dogs and cats sleep twenty hours a day with a minimum of movement or shifting around. When they rise, they stretch half a second and then go sprint. They don’t experience shortening of the muscles that were contracted while sleeping.

Many people sleep on their sides with their hips flexed at ninety degrees for eight hour stretches. Hunter gatherers surely spend many hours a day sitting on the ground with flexed hips, and in a deep squat position, which involves far more hip flexion than sitting in a chair. Why would sitting in a chair tend to shorten the hip flexors any more than these completely natural uses of the limbs? Surely human joints evolved so they do not start to knit themselves together after a few hours in the same position.

Of course it is true that sitting in a chair at a computer all day isn’t what nature intended for the human body. But the unnaturalness of this activity does not consist in having the hip joint flexed to ninety degrees for hours at a time. The worst part of sitting in a chair is probably that it displaces many other healthy movements we could be making instead. In fact, excess computer time probably messes with human movement in many significant ways, but I doubt very much that any of them involve making the hip flexors structurally shorter.

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42 Responses to “Does Excessive Sitting Shorten the Hip Flexors?”

  1. Great, succinct appraisal of a dearly held notion.

    Therapists have been saying this for years, believing it for years, treating patients as if it were true for years and explaining their failures by evoking the “too much sitting” meme for years.

    It’s been nice knowing you.

  2. “Its been nice knowing you.” Do you mean that in the “you’re a dead man” sense?

  3. Yes actually. I think you know that in the sense we use it at Soma Simple this is a compliment.

  4. I am certainly guilty of thinking this way myself. And the hamstrings could easily be grouped together with hip flexors for this one. I understand that with no evidence one cannot say that prolonged sitting would cause these muscle groups to become shortened. But I have to wonder… is there really no correlation? Do some people get “stuck” in patterns of shortening these muscles because of limiting their movement repertoire for long periods of time? A type of “sensory-motor amnesia” as Thomas Hanna liked to call it. On the topic of mechanism what about “adapative shortening?” Is there really such a thing? Do muscles change their resting length with periods of prolonged shortening? Is there any evidence for this mechanism in any literature? Or just another myth. What factors might be at play that would allow some people to sit for long periods without having shortened hip flexors? Awareness? Micromovements…uninhibited ideomotion? And other’s to become more fixed in this regard. Another interesting post Todd.

    • Seth,

      Those are good questions. I definitely think sitting in a chair too much is bad news, just not for the reason that it structurally shortens tissues. The big problem with sitting in a chair IMO is that it displaces other activities which are necessary for maintaining proper movement patterns and tissue length, most notably siting on the floor and in a deep squat and moving back and forth between these positions.

      Humans were built to sit on the ground and in deep squat positions. All kids can sit in a deep squat and move around on the floor with ease, as can all hunter gatherers and people from cultures that sit on the floor and squat. But chairs tend to displace these activities and people don’t engage in them for years at a time. That’s a problem IMO. Feldenkrais is a good antidote! And I agree with your idea that micromovements, awareness and ideomotion are good ways to prevent discomfort while sitting a long time.

  5. Well said Todd. I think the chair replacing the squat in our culture is one of the main problems with chairs. Feldenkrais would discuss how people in other cultures would be squatting easily well into their 80s. You tend not to see it round here much. Use it or loose it as they say. Also, with squatting people don’t generally sit still for long periods as they do with chair sitting, especially in front of screen. They are moving around much more I think, up and down, reaching etc.

  6. A couple of points:

    I have an image of hip flexors slackening off (rather than shortening) when squatting, because the hip angle is so small. This may not happen in sitting.

    Also, what about the opposite – if you talk about hip flexors not shortening, are you implying that hip extensors aren’t lengthening? In which case you could generalise to say that putting a muscle under prolonged stretch doesn’t lengthen it….which would challenge ideas about stretching too.

    I teach Pilates (barefootpilates.co.uk) and blog about genetics (elainewestwick.blogspot.com)

    • Elaine,

      Thanks for the comment. I would imagine that all shortening creates slack, how could it not? Perhaps the hip angle in squatting provides a better place for the slack to go.

      Yes the backside will be stretched in sitting, but I would expect that this is natural and beneficial. The same stretch happens when you sit on the ground or sleep with the knees drawn up, which humans are clearly designed to do for hours at a time. Squatting would give an even better stretch in the glutes. So I would imagine that the stretch helps maintain appropriate length, as opposed to creating excessive length.

  7. Hi Todd,
    Thanks for the post, very interesting. I know this might be a bigger question than what is tackled in this post, but I’m curious as to your thoughts on movement dysfunction in general. When people have forward head position and rounded upper back and shoulders (upper cross), a lot of PT’s claim it’s because of tight anterior muscles that need to be stretched. I’m starting to think that it’s more related to a weakness or inability to activate the correct muscles, rather than a shortness of certain muscles. The same seems to be true of the glutes and hamstrings becoming inactive. What I’m really trying to get at is what causes movement dysfunction in people. Is it mostly tightness of certain tissues, an inability to activate and coordinate tissues well, or a combination of the two?

    • Tom,

      Good questions. I divide factors causing movement dysfunction into two general categories – functional and structural, mesodermal and ectodermal, software and hardware. A structural problem basically means the bones and muscles and connective tissues have not grown into optimal shapes, sizes, and lengths to create optimal movement. For example, many people have lost the ability to fully flex the big toe or dorsiflex the ankle and this limits movement options. These problems develop over many years, probably as a result of failing to engage in activities that send the signals necessary to maintain tissue length – such as squatting and sitting on the ground. Once they occur these changes are very hard to undo. Changing the shape of bones take years. For connective tissue and muscles, its way more stretching than you would ever want to do.

      A functional problem means the brain isn’t coordinating the body as efficiently as it could. For example, some muscle is working too much, or at the wrong time, and some other muscle isn’t working enough or at the wrong time. Could be either one or both. These coordination patterns can be changed by learning new movement patterns, remembering old ones, etc. This is why my approach focuses on changing the ectoderm more than the mesoderm – its easier and quicker.

      • Very interesting. I work at a CrossFit gym and it’s really difficult to help certain people within the confines of the program since it’s basically a one size fits all approach to fitness only consisting of full body exercises. If people have pre-existing structural problems, they compensate immediately during high intensity, full body movements and seem to ingrain the wrong movement pattern. I’m trying to hard help people reap the benefits of crossfit while also correcting movement dysfunction. Your work has been very helpful thank you. Look forward to more.

  8. Thanks Tom. Yes I think that is the challenge with Crossfit and many other forms of exercise as well. The movements will be very beneficial for about 99% of the body but there is likely one weak link in the chain that will either cause compensations or get hurt at high intensity. But all programs have their limitations I suppose and require trainers to find creative ways to address them. Good luck!

  9. I am an RMT, and I generally recommend my clients not sit for long periods. Not so much for the “shortened hip flexors”, although I have heard that before, and your article certainly debunks that theory. I shy away from excessive sitting because of the compression the the Sacro-iliac joint. I find my clients who sit for long hours (truck drivers, cab/bus drivers, office workers, etc.) have compression in their SI region, which in turns causes SI posterior ligament adhesions, which then causes problems with the glutes, piriformis, iliospoas, and issues with their quadratus lomborum. This is what I have witnessed when treating my clients, as well as based on information provided to me in lectures by chiropractors. Any theories on that? Your article seems to be mainly aimed at hip flexor muscles rather than the joints themselves.

    • Tovah,

      Thanks for the comment. Perhaps sitting compresses the SI joint, but how would you ever know? What does it mean to have an SI joint that is compressed? Is there a reliable way to measure whether an SI joint has been compressed? If there is, how do know that it causes lesions in the posterior ligament? How do you know that lesions cause problems in the musculature?

  10. I just shared this post on Facebook with this introduction:

    Todd Hargrove continues to produce posts so similar in sensibility and quality to what I do at SaveYourself.ca that if you got me a little tipsy and asked me if I wrote this, I’d probably say, “Yeah, sure, looks like my work.” It’s a little eerie. Cool. But a little eerie.

    Here’s some thoughts about it.

    Thought the first: you have stated in the article and the comments that sitting is still really bad, but it’s actually not clear just how it can be all that bad if the shortening claim is actually baseless (particularly if you separate the trouble with sitting specifically from sedentariness in general). I think you have dealt a pretty strong logical blow to therapeutic concern about sitting. Which is uncomfortably at odds with my own published opinion that excessive chair time is a super bad idea (see Back Pain and Other Hazards of Sitting In Chairs (Way) Too Much). I may have to reconsider some of my opinions. However, fortunately, I stayed away from the claim that sitting will “shorten your hip flexors.”

    Thought the second: perhaps there is still some hope for the shortening claim. Perhaps the flexors do not actually shorten, but may well still feel significantly shortened, stiff, tight. Indeed, that is my subjective experience. There are other respected experts present who will scoff, but … “trigger points” anyone? I do not believe, and never did, that my hip flexors “shorten” in any meaningful, literal way when I sit all day, but they certainly do become cranky and uncooperative feeling, in the same fashion that is associated with the phenomenon of so-called trigger points elsewhere in the body. That sensation can be quite stubborn, and I am really conscious of it, particularly when I transition from a day of sitting at work to full-power athletic activity in the evening (which I do at least weekly). And there is no question this sensory phenomenon is worse when I’m pulling longer days in the chair.

    • Paul,

      Thanks for the comment and the facebook compliments!

      Re your thought the first, I can think of some reasons that sitting would be bad other than structurally shortening the tissues. First and foremost is that it displaces other movements which are necessary to maintain health. This could cause stress, threat and pain. Also, using the same (fairly unnatural) motor pattern repeatedly could groove some bad movement habits and change coordination patterns for the worse.

      Re your thought the second. I agree that the hip flexors could get “functionally short” after sitting. In other words, their structure doesn’t change at all, but the central nervous system might become a little less capable of lengthening them with power, speed, comfort and accuracy. I would guess that lots of sitting could cause numerous other joint movements to be less coordinated as well, including hip flexion. My jury is out on trigger points!

      • On the badness of sitting, “displaces other movements which are necessary to maintain health” is true of all sedentariness and not sitting in particular. Of course, that long hours of sitting includes sedentariness is relevant … but it still leaves me wondering if there is actually anything really wrong with sitting in particular. I’m drawing a blank.

        Our juries should be out on trigger points, of course. (Sometimes I think the jury is still out on every pretty much every single concept in manual therapy.) Regardless of the etiology or label, there are signs and symptoms, an apparently muscular phenomenon that still needs explaining, after all these decades. You suggested that “the central nervous system might become a little less capable of lengthening them,” and I agree that could well be it. But I won’t rule out the possibility of transient physiological changes in the muscle itself — that’s quite plausible, and there’s plenty of suggestive evidence (i.e. Shah et al). Muscle tissue seems to be able to get into an “unhappy state” of some kind. Permanent shortening (contracture) is not the only way to imagine how hips might feel unpleasantly crimped and stuck-ish after hours in the chair.

  11. Paul,

    Great points. I agree that the displacement theory of why sitting is bad would apply equally to all sedentary behavior. And my guess would be that sitting is not better or worse than any other form of sedentary behavior which involves similarly small amounts of movement. I guess there aren’t really that many types of sedentary behavior – there’s sitting, reclining and lying down.

    Yes there are few issues that the jury has ruled on. I can definitely agree that lack of movement while sitting could cause a local physiological change in tissues – an AIG or a trigger point, or deformation of some nervous tissue. And this could cause pain and stiffness (but not shortness). But I would guess that any other form of sedentary behavior would have an equal ability to cause these problems.

  12. My life (which includes 12 years as a computer programmer) is full of anecdotal evidence that sitting in chairs is uniquely bad. I tend to think it’s the *kind* of sedentary — motionless, under light tension, using fine motor control which requires holding the rest of the body still — that makes it worse. If my hip flexors had been relaxed while I was pounding out code for IBM, I don’t think the sitting would have troubled them at all. But I hypothesize that they weren’t. And it’s certainly my experience that nothing fosters trigger points better than keeping a muscle near complete contraction for a long time. I mean, just do the experiment, with any muscle you like — flex it most of the way and then hold it motionless there, under light tension for twenty minutes, and see how happy it is 🙂

    Thanks for the take down of the idea that they get structurally shorter! That’s certainly a red herring.

    • Dale

      Thanks for the comment. Do the hip flexors hold tension when you sit? Depends on how you sit of course but mine don’t seem to. They are short but seem to be fully relaxed.

      I’m sure you would agree that sitting at a computer and pounding out code is a very different thing from just sitting. Imagine sitting at the beach watching the waves versus sitting in a chair watching the screen. Both have the hips at 90 degrees flexion, but only one is likely to cause discomfort.

      • Are we not pretty much exclusively concerned here with occupational sitting, though? Surely no one is visualizing the hazards of sitting at the beach! 🙂

        The psychology of different contexts aside, though, I think that the hip flexors do “hold tension” when you sit, in the sense of normal shortening to accommodate the joint position. I think what Dale probably meant is that flexors necessarily shorten (a slight contraction) when you flex, just as extensors lengthen to allow the movement. Hip flexors do not dangle slackly like loose ropes while you sit: they shrink elastically to fit the joint position. But that change in muscle length, however, seems to become uncomfortable when sustained. A familiar example: when you sleep with your neck turned well to one side, some muscles are shortened, others are elongated … and none are happy if it goes on for long.

        A related point here is that I don’t think it’s just the flexors that have trouble with this: the extensors are also fairly elongated, and they also become uncomfortable. My gluteus maximus seems just as cranky as my flexors!

        It’s not that either flexors or extensors are in an ‘extreme’ position, but the durations can be extreme. Typical sitting places the hips clearly away from the mid-point of their full range, but it’s no stretch, and there’s still plenty of flexion range remaining. But it is sustained for literally hours.

      • Todd, God knows. The days are long past when I could palpate my psoas while sitting. I was hoping one of you skinny guys could tell me 🙂

        In my programmer days, before I knew anything about bodywork, I had a lot of lower back trouble. Nowadays, very little: but when I do get what feels like the same kind of low back pain, from the same pattern of sitting — what I usually find is mild TrPs in the glute medius and severe ones in the psoas, and the relief I get from squishing them makes me think that my psoas is what really dislikes the chair-sitting.

        But the tensed psoas is complete speculation. All I have is a repeated sequence of sitting-work -> low back distress -> psoas TrPs -> Psoas TrP work -> low back relief. And a sample size of 1 🙂

  13. Yes, the concern is with occupational sitting. And my concern with occupational sitting is not hours of hip flexion, its with something else – eye position, use of hands in repetitive motions, stressful psychological context, etc.

    I agree that a muscle that is tense for a long time may have a problem, but I don’t think you need continuous tension in the hip flexors to sit in a chair. The hip flexors are needed to tilt the pelvis forward but once its there, the back of the chair can hold the pelvis in place, or you can tilt the pelvis forward enough so that gravity maintains pelvic angle as opposed to hip flexor contraction. Palpate your hip flexors as you do this and see what you get.

    In the neck twist example I would guess that the elongated muscles would suffer more than the shortened ones, but only if they are holding tension to prevent further twist. Same with the hip extensors. Also, there are many reasons to get a sore neck from a twist that have nothing to do with muscles.

    Interesting discussion.

  14. Hey Todd

    Great post.
    I’ve found Moshe’s first ATM in the “awareness through movement” book a revelation in terms of sitting, squatting and going up and down to/from standing.
    My understanding of the lesson is that it has helped me to realise when I “bear-down” on my feet in order to stand from stting it rolls my pelvis backward and (relatively) extends the hips joint when they need to flex. By thinking of almost drawing my knees to my chest as I hinge forward to stand I feel my hip flexors are able to shorten and it feels smoother in the hips, and takes work away from my lower back.

    The same “bearing down” through the feet would tend to “tighten”(or at least the sensation of) the hip-flexors in sitting by pushing them out and not allowing them to shorten! This means other back extensors and hips flexors (erectors and tensor fascia latte) work overtime to keep me sitting upright.

    I’ve also used this idea in going down into a squat, the idea of drawing the knees up creates a sense of space at the front of my hip. In powerlifting terms it’s called “pulling down into the hole”.

    In Ida Rolf’s “Rolfing”, she writes of the psoas being able to sink back into the back rim of the pelvis to function properly. This idea feels like what happens for me with this “drawing the knees up” idea. I’ve also noticed a similar effect in classic flexion ATM lessons, and the ability of the psoas to “move back” makes the leg(s) lighter to lift supine.

    I attended a workshops for PTs and it was stated that there is evidence to suggest most people’s psoas is too long and weak rather then short and tight.
    I haven’t looked into the research but certainly the ability to shorten the psoas in a functional way seems like something worth exploring for many people.

  15. Of course it’s possible to be sitting with hips “over”flexed as well.
    Whether the psoas is actually (ever) pulled forward or not I don’t know. If it does it makes sense that this pattern could also contribute to the hyper-arched lumber. If the psoas where back in the pelvis it might not pull the lumber.

    Nevertheless the point is it may not be so much the Length or shortness of the muscle but the way it shortens or lengthens according to the task at hand, and in concert with all the other moving parts of the whole person.

    As an aside I went to a talk on the dangers of sitting recently, expecting a bio-mechanical presentation. Instead it was all about the significant increased risks of cancer, diabetes, cardiovascular disease etc.

  16. I would continue to the conversation, but it is late Friday afternoon, I have been sitting here since 7am, and, even if I am not entirely sure what the problem is, I have really GOT TO GET OUT OF THIS CHAIR NOW!

    🙂

  17. A general rule,until a better one comes along, is that the body finds discomfort in the tandem of position and length of time.The dynamic needs to include the amount of work required to maintain the position.That will bring into play your body challenges and personality.I cant think of anything,when done too much or for too long,doesnt have consequences.

  18. Dale,

    Haha. Thanks for the data on your experiment.

  19. Is there a correlation here with the startle reflex? Exactly what muscles does the startle reflex fire? The hamstrings also tend to be short. Are the psoas and hamstrings fired by the startle reflex? People often get pain between the shoulder blades. Are those muscles fired (and being exhausted) by the startle reflex?

    • Tim,

      The startle reflex tends to fire the flexors of the body, and in many cases probably the hip flexors as well. Not sure about the hams as they are both flexors and extensors. In any case, I don’t doubt that too much sitting could cause many forms of neurological disturbance, including inducing mild startle reflex activity. But none of this is likely to actually physically shorten the hip flexors, provided you eventually use their full range of motion sometime each day.

  20. Does the Feldenkrais Method or Z Health offer assessments or exercises for short hip flexors? I assume “short” hip flexors is rather common so I’d be surprised if they didn’t have anything to offer.

  21. Tim,

    In Hanna Somatic Education, one of the three stress reflexes we help people to reverse is the startle reflex. Those who sit long hours slumped at the computer are more likely to habituate this reflex. Add to that stressful reading, bad news, and you have a perfect set-up for habituating the startle reflex – the brain’s most primitive response to danger, anxiety and fear. The muscles involved in the reflex are the flexors, adductor, up to the SCM and other muscles of the neck. The rectus abdominus is tightly contracted in this reflex, which causes the pelvis to tuck under. Most people who habituate this reflex have a slight bend in their knees (look at an elderly person who has begun to collapse in on themselves from this reflex). This causes the hamstrings to tighten in co-contraction. The pain in the shoulder blades occurs due to the constant battle between the flexors and extensors of the body keeping trying to keep you in gravity. This is what Thomas Hanna, author of the book, Somatics, called “the dark vise.”
    I agree wholeheartedly with Todd when he says that intentionally allowing the muscles their full range of motion is an excellent way to thwart getting stuck in that reflex! Remember to move!
    That “stretch” Todd talks about that animals do when they get up from rest (and that they apparently do about 42 times a day!) isn’t a stretch, but a “pandiculation.” It’s the brain’s way of “waking up” of the CNS by contracting the muscles and then slowly lengthening them. This allows the brain to regain conscious control of the muscles. It’s the technique we use in Hanna Somatics to teach people to regain control of “amnesic,” chronically contracted muscles. It’s miraculous and it’s easy to do.

    • Martha,

      Thanks for the comments. I’ve read Hanna’s book and enjoyed it and have also done some Somatics lessons. I’m in my third year of training to be a Feldenkrais instructor so of course I see the similarities.

      As far as pandiculation goes, I am curious whether it has anything to do with ideomotion.

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