Human lumbar spine creep during cyclic and static flexion: creep rate, biomechanics, and facet joint capsule strain. Ann Biomed Eng. 2005 Mar;33(3):391-401.
From the study:
There is a high incidence of low back pain (LBP) associated with occupations requiring sustained and/or repetitive lumbar flexion (SLF and RLF, respectively), which cause creep of the viscoelastic tissues. The purpose of this study was to determine the effect of creep on lumbar biomechanics and facet joint capsule (FJC) strain. Specimens were flexed for 10 cycles, to a maximum 10 Nm moment at L5-S1, before, immediately after, and 20 min after a 20-min sustained flexion at the same moment magnitude. The creep rates of SLF and RLF were also measured during each phase and compared to the creep rate predicted by the moment relaxation rate function of the lumbar spine. Both SLF and RLF resulted in significantly increased intervertebral motion, as well as significantly increased FJC strains at the L3-4 to L5-S1 joint levels. These parameters remained increased after the 20-min recovery. Creep during SLF occurred significantly faster than creep during RLF. The moment relaxation rate function was able to accurately predict the creep rate of the lumbar spine at the single moment tested. The data suggest that SLF and RLF result in immediate and residual laxity of the joint and stretch of the FJC, which could increase the potential for LBP.
This study is largely confirmation that both sustained and repeated spine flexion decreases passive integrity of the spine. The take home message is that people with low back pain, and people that don’t want low back pain, should not sit prolonged in chairs with no lumbar support, should avoid stooped postures with a flexed spine (rounded back), should not exercise with movements into spine flexion (like situps, crunches, and stiff legged dead lifts) and should avoid stretches into spine flexion (like toe touches, posterior pelvic tilts, and knee to chest stretches). What they should do, and what I generally teach in physical therapy is the maintenance of a neutral spine while sitting with good support from chairs, proper adjustments of seating position while driving, and exercises to increase core and extremity strength all performed with the spine neutral and movement taking place at the hips and shoulders, rather than the waist. Exercises like standing cable rows and presses, mat exercises with a neutral spine, squats and RDLs. If the patient has too much pain for active exercise at first, I will start with electric muscle stimulation not just to the painful region but concurrently throughout the abdominal region which gives a 2 for 1 benefit of immediate pain reduction while improving core strength.
All of the above largely complements much of the Stuart McGill research that I am a fan of. However what was new to me was a citation that it is facet joint strain from flexion stretches that most likely contributes to muscle spasms. This agrees with my clinical observation that most often when you correct postures and improve core/hip motor control, strength and endurance, muscle spasms and “trigger points” go away. However if you just massage them or poke them with acupuncture or dry needling you are merely treating the symptom but not the cause, and if a physical therapist gives the patient typical spine flexion exercises like knee to chest and pelvic tilts, you are actively making the patient worse. What’s unfortunate is that I know a number of “back pain specialists” who still adhere to 1930s based Williams flexion exercises, and 1980s based McKenzie exercises (generally the latter part of his program only) both of which stretch the spine into flexion.
Thanks for reading my blog. If you have any questions or comments (even hostile ones) please don’t hesitate to ask/share. If you’re reading one of my older blogs, perhaps unrelated to neck or back pain, and it helps you, please remember Spinal Flow Yoga for you or someone you know in the future.
Chad Reilly is a Physical Therapist, obtaining his Master’s in Physical Therapy from Northern Arizona University. He graduated Summa Cum Laude with a B.S. Exercise Science also from NAU. He is a Certified Strength and Conditioning Specialist, and holds a USA Weightlifting Club Coach Certification as well as a NASM Personal Training Certificate. Chad completed his Yoga Teacher Training at Sampoorna Yoga in Goa, India.
2 thoughts on “Low Back Pain: Cyclic and Static Spine Flexion Both Bad for the Back”
I just stumbled upon your posts and find them very informative. I have a question for you though regarding the McKenzie Stretches. I have always been told by Orthopedists that backward flexion of the spine is absurd-especially with patients that disc problems or vertebral alignment issues.
Can you either comment on this or can you point me in the direction of some information on this? I know you have said that neutral spine is the way to go(and I agree) but I want to read up on The Mckenzie Method more to be better informed.
Hi Kerry, just to make sure we’re talking about the same thing, when you say backward flexion, you mean spine extensions right?
Research on pig spines does show that spine extension can sometimes (it was about 50/50) reverse disc protrusions if the disc isn’t degenerated too much. However that same paper stated that if more than 40% of the original disc height was lost that extension would likely be ineffective. What wasn’t known, per that paper, was that if you had already torn some of the anulus fibers, allowing the nucleus to migrate rearward, if extension to push it forward would do any long term good. For example if the fibers are breached, and for a disc protrusion they must be, extension might push the disc forward, but the very next time you tie your shoes, flexion would put you right back where you started. So that might be one of several reasons why Mckenzie extension stretches sometimes work in theory but in the real world don’t seem to do much to low back pain.
I do think McKenzie’s general advice in his books to avoid aggravating flexion postures is quite good, though I think the lumbar rolls he suggests when sitting are too big. I think another problem with “Mckenzie method” is that after pain is lessened, either due to his treatment, or just due to time, he advocates flexion stretches to restore lost range of motion. The obvious problem here is that his flexion stretches at this point are the very same spine motions that most frequently result in disc herniation in the first place. For more information on Mckenzie method and back pain, I have a fair number of additional links in the discussion above. I know they are long, but maybe just click on the blue words. For more information on Mckenzie method in particular I would encourage you to read his books. I don’t use his method but his books were still a good read. For my favorite studies and my comments on the treatment of low back pain, I have a fair number of blogs on the topic. And feel free to ask more questions.