Hamstring flexibility is not correlated with back pain (when standing, running, most sitting and exercise).
Where did the myth come from that mistakenly led to the popular practice of hamstring stretching for back pain?
Plus, the off-shoot myth that mistakenly put crunches and flexion-based core exercise
into back pain rehab - where they do a lot of mischief and not all the good that was hoped.
You are on Dr. Bookspan's no ad web site - hundreds of articles and info pages dedicated to getting you back to your life - healthy, mobile, and happy. This page tells interesting work I did about your hamstrings.
I did initial work (pilot study) that found no relation between amount of hamstring flexibility and any incidence of lower back pain. It went against common practice of prescribing hamstring stretching for back pain. My results were not well received. I was actually boo'd at a prestigious sports medicine conference.
I quietly put my results on the shelf, and continued over years to find out why there was no relation and what else might be involved.
In the meantime, respected names in spine research found the same results in their studies - no relation between hamstring flexibility and incidence of back pain.
I had already done work that found that too much inward curve of the lower back (hyperlordosis/ swayback) caused pain with long standing, from compressing and pinching the area (explained on the Back Pain With Standing page, and a bit about the studies on my ab syllabus). In continuing work, I found that during the act of stretching hamstrings, the inward curve of the lower back becomes less - only during those few seconds, of course. For the many people with lower back pain from too much inward curve, the reduced angle and lumbar lengthening provided temporary relief from the compressed pinched ache that hyperlordosis causes. Of course, when they stood up and went back to standing swaybacked (too much inward angle) the pain eventually came back and they felt they needed to bend forward and stretch again to relieve it. The brief reversal of symptoms during back stretching became mistaken for relief from the hamstring stretch. Brief hamstring stretching became further confused with lifelong hamstring flexibility. Like "whispering down the lane" it next changed into hamstring flexibility prescriptions for any kind of back pain. Then worse - people thought that the temporary bending forward during crunches and other flexion exercise like Pilate's was curing back pain, wrongly thinking strengthening or other mythology was the reason, when it was just a temporary reversal of the bad posture (lumbar sway) that was causing the problem. Temporary bending forward felt good after crushing the lower spine with all the excess inward sway.
It was mistaken identity. The resulting myth would have been harmless except that the same lower back rounding and forward bending (flexion) that co-occurs during certain hamstring stretches and conventional core exercise puts herniating forces on them over time. It was one of several reasons that hamstring stretches are a common cause of lower back pain, not a fix. It wasn't fixing the cause, and it wasn't even a healthy way for temporary relief. Another interesting reason is that hurt hamstrings may hurt at the place hamstrings attach to your "sit" bones - the very area assumed to be sciatic pain alone More on this on my Stretching Smarter page and Fix Lower Back Pain page.
What to do instead? If you get the kind of lower back pain felt with long standing, walking & running, and feel that bending over forward or sitting brings relief and stretches out the ache, you probably stand with too much lumbar arch (hyperlordosis). Instead of keeping the bad posture and getting recurring lower back pain, then doing hamstring stretches to try to temporarily curb it, prevent the entire problem with neutral spine. Then you don't over-curve and compress the lumbar spine (you stop your swayback with healthy standing position) and don't cause any back pain in the first place. Then, to get a healthy lower back stretch built into your regular day, use good bending, explained on the Fix Lower Back Pain page and in my books. For effective and functional hamstring stretches without flexion, see my book Stretching Smarter Stretching Healthier, with one helpful stretch in my web site Stretching Smarter article. It is a whole world of healthier smarter movement mechanics and daily habits. You won't get the pain and will also move and stretch in healthier way to stop future damage.
When do tight hamstrings change hip tilt? When you sit with legs straight out in front of you, tightness can pull the pelvis so that lumbar lordosis decreases (back rounds, as above). Sitting with your back rounded for long periods presses discs outwards and makes muscles ache. Most people don't sit on the floor with legs straight out, they sit in chairs with knees bent. Hamstrings are not involved if you sit with your back rounded when your knees are bent. Then, you are just slouching.
Disclosure and Conflict of Interest Disclaimer
This study was not funded by anyone or any agency, and has no financial relation or obligation to anyone. Funding agencies have gone out of their way to meticulously ignore me. I have no financial relationship with any manufacturer, vendor, service or product provider discussed in this study. These studies were done before I wrote the book The Ab Revolution. The training manual that became the book was the result of the findings of my work, not the other way around. The book is also not commercially funded or related to any product sales. The story is here - look for "A Short Story of My Work Developing These Methods."
Check Back - I am adding more on the myth that tight hamstrings reduce lumbar angle (making a flat-back) and cause lower back pain. For now, consider all the people who have tight hamstrings and have too large lumbar angle (tilt their hip forward / swayback) - maybe even yourself. Why didn't tightness prevent your swayback or even pull you to neutral spine? Because hamstrings don't work that way, and swayback can occur from tightness in the front of the hip, not the back, from tightness in other places, even without any tightness (when it's just slouching). More to come!
The Hamstring Studies
1. My Pilot Study - I Found No Relation Between Hamstring Flexibility and Lower Back Pain:It was so often repeated that you have to stretch your hamstrings to prevent or fix back pain, but why? I set out to find if there were any relation between the two. People often repeat the mistaken idea that tight hamstrings tilt your hip that reduces the lumbar angle, making back pain, but hamstrings don't work that way and if they were that tight, you couldn't take a step forward. (Plus if that were true, the prescription would be to make hamstrings tighter to reduce the too large angle, called hyperlordosis, which causes much lower back pain). Many years ago, I looked at 167 of my patients and students. I carefully measured hamstring flexibility and noted if they had back pain at the time, or at any time in the past. Running the data comparing flexibility to incidence of any lower back pain, resulted in no relation, no correlation, nothing that linked the two.The details of how I measured flexibility (continuous data measures) was as follows:
Zero degrees is lying flat on your back with both legs down on the floor together,
45 degrees is one leg lifted to diagonal, 90 degrees is leg able to stretch to perpendicular - pointing to ceiling, and so on.
I collected flexibility in actual degrees - continuous numbers from zero to 180 if they lifted leg all the way back to their ear in a lying down split.
I measured flexibility in the dominant leg and also both legs together to make it more like a "sit and reach test" but keeping the lower back from flexing or rounding in order to try to isolate hamstringsI presented my work at scientific conferences and they practically threw tomatoes at me, saying my work could not be true because "everyone knew" that hamstring tightness meant you would have back pain and therefore stretching would fix it and that meant that hamstring flexibility was a predictor of back pain. There were so many inductive leaps and faulty premises in those statements that it was hard to address them in ways that would appease or enlighten the mob. These were doctors who were even keeping people out of jobs if they had tight hamstrings. They said that tight hamstrings necessarily meant the people would get back pain, and the employers didn't want to pay Workmen's Compensation claims. That's how bad this myth had gotten.
2. Then What Happened?In subsequent years, highly respected researchers duplicated my study - and found no relation between hamstring flexibility and back pain.
During that time, I did more work on separating if hamstring flexibility itself, or something in the act or motion of hamstring stretching brought relief. With no correlation between hamstring flexibility and lower back pain, what else might hamstring stretching do or include?
Not a lot of my work is published in journals. I am busy trying to get work done and don't present or publish all (or even much of) my work Publish?? I'm trying to accomplish something here!
For the many who have been asking, I put the results of my studies of my patients with knee pain on my Lower Body page and a few of my lower back pain studies on my Ab Workshop syllabus. Here are the results of this study on hamstrings:
3. The next work - Comparison of Neutral Spine and Hamstring Stretch for Relief of Hyperlordotic Lumbar Pain
A widespread prescription for lower back pain (LBP) is hamstring stretching. Some patients report relief from hamstring stretching, others, no effect or worsening. A pilot study of 167 subjects found no relation between hamstring flexibility and LBP. Subsequent independent studies confirm no relation between hamstring flexibility and LBP (1,2,3). Disc injury (4) and osteoporotic fracture (5) can be caused and worsened flexion, such as that involved in conventional hamstring stretch.
Previous work determined that hyperlordosis (swayback) results in one form of lower back pain (LBP) by compression of facets and soft tissue, and shortening lumbar height (6,7). Neutral spine (NS) lengthens and unloads, directly stopping LBP(8,9). Momentary incidental lumbar lengthening during hamstring stretch briefly stops symptoms. Spinal stenosis symptoms also often reduce with flexion (7). It is proposed that temporarily reversing swayback with hamstring stretching became confused with the separate entity of flexibility. The purpose of this study is to compare a neutral spine method, Ab Revolution (AR) with conventional hamstring stretching (HS) for LBP from hyperlordosis.
Pilot study of 167 subjects measured degrees hamstring flexibility using straight leg raise test, compared to nominal measures of active LBP, previous LBP, or never LBP. Of initial 167 N, 113 had active LBP. Of these 113, 92 reported wanting to bend forward, lift one leg, sit, or bring knees to chest to relieve symptoms.
Following the pilot study, a new study group was formed from original subjects. Of the initial Pilot study, four had been lost to follow up. The remaining 88 were divided into two groups: Neutral spine training group called Ab Revolution (AR) N=44, and a group receiving daily conventional hamstring stretching (HS) N=44. Hamstring stretch group (HS) performed hamstring stretches of their choosing or prescribed by their physical therapist twice daily.
Nominal outcome measures of ability to employ neutral spine (NS), flexibility (increase, decrease, no change), and LBP were assessed at day 1, 6 weeks, and 6 months, analyzed using Chi-Square.
Of the Hamstring Stretch (HS) group, 41 of 44 increased hamstring flexibility, and there was no significant lasting reduction in LBP, 39 had brief symptom relief during hamstring stretching but return of pain with upright stance and activities of daily living, 43 of 44 were measured as not using neutral spine when standing or ambulating (no NS). 18 of 44 had increase in LBP.
Subjects using neutral spine training (Ab Revolution or AR) showed significant reduction of LBP during daily activities at day 1, 6 weeks, and 6 months. At 6 months 40 of 44 had no LBP. LBP was not correlated to change in hamstring flexibility in either group.
1. Incidental lumbar flexion from hamstring stretching, not hamstring flexibility, reduces LBP by reversing swayback - at the time of stretching.
2. Temporary reversal of symptoms from swayback (hyperlordotic lower back pain) occurring during hamstring stretching, became mistaken for relief from the hamstring stretch itself. Hamstring stretching became further confused and combined in practice with hamstring flexibility. Hamstring flexibility prescriptions became further derivative to include any kind of hamstring stretches for any kind of back pain.
3. The temporary bending forward during crunches and other flexion based "core" exercise does not cure back pain through strengthening. The temporary reversal of the original problem of slouching with too much inward lumbar curve provides temporary relief that is mistaken for real change or cure. The pain from hyperlordosis comes back as soon as the person stands and resumes the real cause - not weakness, but standing in hyperlordosis. Crunches and core exercises do not change that. This is why there is only temporary relief from conventional exercises, or chronic pain that "has to be managed through recurring flexion" or intermittent pain that is confusing and "no one understands why it comes and goes." No amount of strengthening or core exercise makes you prevent the hyperlordosis which is the root of this one kind of pain.
4. Hamstring stretching is not curative for lower back pain
5. Hamstring stretching and flexion based core exercises may aggravate specific lower back pain, and over time, create new lower back injury.
6. Lumbar lengthening and restoring neutral vertebral angle through neutral spine technique (AB Revolution AR) gives sustainable pain relief by directly stopping cause of LBP from swayback (hyperlordosis).
7. Using neutral spine through AR is functional; stopping cause of LBP and integrating needed resting and active length of lumbar spine during activities of daily living.
1 Jones MA, Stratton G, Reilly T, Unnithan VB. Biological risk indicators for recurrent non-specific low back pain in adolescents. Br J Sports Med. 2005 Mar;39(3):137-40.
2. Grenier SG, Russell C, McGill SM. Relationships between lumbar flexibility, sit-and-reach test, and a previous history of low back discomfort in industrial workers. Can J Appl Physiol. 2003 Apr;28(2):165-77.
3. Jackson AW, Morrow JR Jr, Brill PA, Kohl HW 3rd, Gordon NF, Blair SN. Relations of sit-up and sit-and-reach tests to low back pain in adults. J Orthop Sports Phys Ther. 1998 Jan;27(1):22-6.
4. Veres SP, Robertson PA, Broom ND. The morphology of acute disc herniation: a clinically relevant model defining the role of flexion. Spine (Phila Pa 1976). 2009 Oct 1;34(21):2288-96.
5. Tzermiadianos MN, Renner SM, Phillips FM, Hadjipavlou AG, Zindrick MR, Havey RM, Voronov M, Patwardhan AG. Altered disc pressure profile after an osteoporotic vertebral fracture is a risk factor for adjacent vertebral body fracture. Eur Spine J. 2008 Nov;17(11):1522-30. Epub 2008 Sep 16.
6. Bookspan, J. Identifying and Reversing Hyperlordosis as a Factor in Lower Back Pain. Medicine and Science in Sports and Exercise, 39:5 May 2007.
7. Bookspan, J. Hyperlordosis Retraining Method Relieves Lumbar Disc and Stenosis Pain—An Unexpected Finding. Medicine and Science in Sports and Exercise, 41:5, 2009.
8. Bookspan, J. Ab Revolution functional core retraining relieves low back pain more effectively than conventional physical therapy. Medicine and Science in Sports and Exercise, 38:5, 2006.
9. Bookspan, J. Functional Core Retraining Superior To Conventional And Pilates Core Training In Remediating Low Back Pain. Med Sci in Sports and Exercise, 37:5. 2005.
In these references - respected names in spine research found the same results in their studies - no relation between hamstring flexibility and incidence of back pain.
"Even historians fail to learn from history."
- Professor John Gill - Star Trek episode 52 Stardate unknown, Patterns of Force
- Study publication (abstract): Bookspan, Comparison of Neutral Spine and Hamstring Stretch for Relief of Hyperlordotic Lumbar Pain J. Medicine and Science in Sports and Exercise, Volume 44:5 Supplement. 2012.
- Study presentation at the 59th Annual Meeting and 2nd World Congress on Exercise is Medicine of the American College of Sports Medicine at the Moscone Convention Center in San Francisco, CA, 1 June, 2012.
What Does This All Mean? Applications -
1. This means you have a quicker more direct way to stop this kind of lower back pain - Stop the cause by using neutral spine. Neutral spine is used during standing, walking, sports, and all your regular activities.
Hyperlordotic lumbar posture (swayback) has been previously identified as a direct contributor to lower back pain during and after standing, carrying, and ambulation (walking, running, upright movement) (6,7,8). The increased lumbar angle of hyperlordosis physically compresses bone, nerve, and soft tissue. Think of a straw pinched backwards. Two types of hyperlordosis are shown:below - hip tilt (middle) and thoracic lean (right). Both may also appear together. For comparison, neutral spine is at left:
Another example of thoracic lean back (that is what I have named it as I haven't seen it identified in any previous sports medicine sources).
Thank you for photo by n0nick http://flickr.com/photos/n0thing/41750513/
2. Hyperlordosis is common among athletes and non-athletes regardless of abdominal strength, as strength alone does not cause movement. Movement out of poor posture is what corrects hyperlordosis. Moreover, overly arched (hyperlordotic) posture is mistakenly encouraged as good posture, as a method to lift or squat more weight, as the weight is shifted to the facet joints and off the muscles making the lift seem easier, with long term consequences from the joint loading - example below at left with neutral spine comparison at right. Hyperlordosis seemed to be a fad in the fitness industry in the 1990s and decade of 2000.
3. Overarched spine (left) was a fad in fitness and the cause of much lower back pain, even though it made lifting easier. Lifting was easier because it shifted load to the lower spine and off the muscles For spine health, it's better to use your muscles than rest the load on the joints. Save your slouching and bad form for emergencies.
Correcting hyperextended angulation to neutral spine has been identified to directly unload and correct the source of pain in hyperlordosis(6) disc and stenosis pain(7) more effectively than conventional strengthening programs (8,9).
4. What About Stretching?
Stretch programs for lower back pain are common in therapy programs, however with often unsatisfactorily low or inconsistent success rates. Conventional hamstring stretches are non-specific—they do not directly train reduction of hyperlordosis during standing, gait, exercise, and activities of daily living.
Another interesting reason hamstrings were misidentified with back pain is that sore hamstrings and hamstring pulls (from bad stretches and movements) may hurt at the place hamstrings attach to your "sit" bones (ischial tuberocities - the bottom bumps of your pelvis/ hip) - the very area often assumed to be the place for sciatic pain alone (lots of things can hurt there). Then a mistaken diagnosis of sciatica or disc pain occurs and stretching the hamstring helps, when it was the thing that was hurt i the first place. Then a mistaken association with stretching hamstrings fixing sciatica.
When the pain was really from discs and soft tissue from chronic bad bending, the hamstring stretches themselves only make things worse in the long run. Most stretches feel good for a moment, (like smoking a cigarette) but over time damage little buy little and reinforce bad habits.
6. What to do instead of hamstring stretches for lower back pain? If you get the kind of lower back pain felt with long standing, walking & pruning, and feel you want to bend forward to stretch out the ache, you probably stand with too much lumbar arch (hyperlordosis). Prevent that with neutral spine - summarized in my Abs Article, and explained fully in my books, particularly The Ab Revolution. Get functional built-in lower back stretch every time you use good bending - which should be many many times every day, summarized on the Fix Lower Back Pain page and explained in detail in my books.
Mistaking correlation for cause and effect is a classic serious mistake in science.
The myth of hamstring flexibility as curative for back pain recurring with standing walking and running was misunderstood from the temporary lumbar stretch co-occurring with hamstring stretching that reversed the hyperlordosis that was causing the back pain.
The same mistaken identity seems to be the reason people mistakenly believe ab training and the forward bending of Pilates and other pop exercise systems "helps" - it just feels good for the moment for people with lumbar pain from swayback because they are temporary stretching it the other way. It's not a healthy fix and not a long term one.
Better Hamstring Stretches
Appreciation and thanks to Paul Jenkins for proofreading and math checking for this study. He is my Academy Director of Silly Syndromes who keeps us laughing (and sane) in the world of crazy fitness claims. Appreciation and thanks to Peggy Santamaria for making (yet another) banner for me to use at my presentation of this work. Ms. Santamaria is my Academy Director of Developmental Ability - teaching my work to developmentally disabled adults, who go on to gainful employment doing healthy landscaping, snow removal, cleaning, mail room work, and more. See my Academy Honors page for some of their photos and good work, and Academy for more of all we do and how you can be part.The ACSM fellow who sponsored this work for presentation at the 59th Annual Meeting and 2nd World Congress on Exercise is Medicine is Catherine Ratzin Jackson, Ph.D., FACSM, who states, "The present study challenges current thinking and the evidence is compelling."
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