I will respond to the rest of the post when I have more time, but I just wanted to address this statement.
[quote]andersons wrote:
Honestly, I don’t think many chiropractors understand the spine as well as McGill. He is a PhD who has devoted his career to understanding, measuring, and modeling how the spine works. The book I recommended is a scientific summary of the body of evidence amassed thus far.
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So, what you’re saying is that you believe that someone with a doctorate of philosophy (PhD), knows more about the spine than people with medical doctorates (M.D)? Seriously? I mean seriously?
A PhD is no joke, don’t get me wrong. But it’s definitely not on par with an M.D. when it comes to the medical sciences. Sorry, but chiropractors understand the spine better than anyone else on the planet. It’s their entire profession and once again, they had to graduate from med school in order to get their M.D.
Thank you both for keeping this civil and bringing up both valid points on both sides. Although I’m still not sure on both sides, I enjoyed reading the arguments by both of you completely.
So what IS the “normal” ROM for each spinal joint?
End ROM at ANY joint is a potential for injuring the joint or causing chronic irritation and inflammation.
The safe ROM for each individual facet joint of the spine is quite small, just a few degrees. The problem is that when stretching the back in overall flexion of the torso, you cannot control or limit the ROM at each individual joint. Many people have movement patterns which cause too much ROM at a joint, such as L5-S1. In such cases every flexion movement stresses the disc, eventually leading to tears, herniations, and ruptures. This happens in the majority of people and doesn’t always cause pain, but when it does, the dysfunction is serious.
Further, I would ask you, Where is the evidence that stretching the lower back protects against injury?
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I am not going to argue with you that many people have poor movement patterns, a lot of which have to do with poor hip mobility (especially hamstring flexibility). And that if they don’t remedy this it will lead to injury (especially if they are lifting weights).
The topic of whether spinal hyperextension came up in a “Sports Injuries” class that I took (which was consequently taught by a sports chiropractor) one time. Now most people will say that spinal hyperextension can be harmful and dangerous. Surprisingly what the teacher (chiropractor) said was that the spinal disks are extremely efficient at handling longitudinal forces (top to bottom) and that hyperextension and flexion were both natural and not harmful movements for the spine.
The movement he said was dangerous was spinal rotation. The analogy he used was the lid of a pickle jar. Now, you’d be pretty hard pressed to push the top of the pickle jar down through the bottom of the pickle jar, or rip it straight off. But, it’s fairly easy to unscrew it.
Well, that would first only apply if you were letting your head hang. What if you lie on your back and pull your knees up into your chest (stretching your lower back), or you support your weight with your hands out in front of you while you are stretching (thus taking load off of the disks)? Would you still say that those would be harmful movements? Do you really think that disks which are capable of supporting hundreds (if not thousands) of lbs are going to get damaged by partially (or possibly not at all) supporting the weight of the head (which weighs on average between 4.5-5kg)?
Ah, but couldn’t it also be said then that because the antagonists to the spinal erectors (the rectus abdominus) must contract to stabilize the spine and tend to be weaker than the erectors that stretching the erectors could potentially help in stabilizing the spine as well? I mean, in order for the spine to retain it’s natural curvature the rectus abdominus, transverse abdominus, internal and external obliques must all contract along with the erectors. Since the spinal erectors tend be be very strong and the abdominals tend to be weaker in comparison, by your own example stretching the erectors would help to even out the imbalance.
Of course strengthening all of the muscles that stabilizing the chain as well would probably be the best way to go. Of course one of those muscles (the abdominals) would involve spinal flexion (because that’s one of their primary functions). Do you also believe that exercises like crunches, leg lifts, side bends, etc… are also harmful to spinal health? If not then why? They involve spinal flexion?
Oh, ok. Well then I’ll have to take your word for it as I really don’t have the money to pick up a copy of the book atm.
Nor was it meant to, only to argue against the idea that different rules would apply to the spinal erectors than would apply to other muscles.
Well, I’m not really going to argue with that. Just that it is not harmful for the body to perform movements that it was designed to perform. Flexion and extension for hinge joints for instance are perfectly healthy, while abduction and adduction would be very harmful. The spinal joints are unique, that much I’m not arguing, but to suggest that performing one of the movements which they are designed for (spinal flexion and extension) is harmful just once again doesn’t make sense. And like I said before, I’ve never heard any other authority on the subject suggest that they were.
Arbitrarily? Who said anything about arbitrarily increasing ROM? Yes, there is such a thing a hypermobility, and I’m not advocating it. I’m not suggesting that one should seek to become a contortionist.
I won’t argue about the CNS’s involvement. But once again you are attributing a completely different set of rules to the spinal erectors than you would attribute to other muscles. Let me ask you this, what does Cressey/McGill suggest that you do to improve hip mobility? Not move at the hip joint? No, of course not. They suggest that you practice drills in which you perform movement at the hip joint. Why? Because moving your joints is a sure fire way to improve their mobility, and not moving them is a surefire way to limit their mobility.
Once again, what about movements like crunches while lying on your back, or doing leg lifts while hanging from a bar, those both involve spinal flexion and yet there is no leverage from the head and shoulders. Also, once again I’d attribute poor body mechanics to a lot of people injuring those spinal joints, due in large part to poor hip mobility. Loaded spinal flexion is a bad thing, that I’m not arguing with you about, but the simple act of flexing the spine doesn’t necessarily mean that you’ll injure yourself.
Are you seeing what I mean by this not being so black and white yet? You seem to be (and this could be because McGill, Cressey, or who ever you’re getting your information from worded it this way) stuck in the mind set that the only way that you can flex your spine (or stretch your erectors) is by doing an unsupported (loaded) spinal flexion (like a standing toe touch). This isn’t the case and your reasoning so far, while I’m not arguing with some of it, hasn’t given any evidence to support the direct correlation between the joint action of spinal flexion and injury.
Sentoguy, you obviously have a much better grasp of all things spinal than I.
With that being said I can’t say I agree about all muscles being the same. It seems to me that the spinal erectors are the only muscles that are regularly seen to go into spasm. Of course, this could just be an argument for stretching them.
I know when I stretch mine I seem to have fewer issues.
[Warning: Another long post. Read only if you are interested.]
I previously recommended “Low Back Disorders: Evidence-Based Prevention and Rehabilitation” by Stuart McGill. Revisiting the free excerpt now provided by Google Books has reminded me why I was so impressed by this book years ago – “Evidence-Based.” There are no recommendations here based on speculation, anecdotes, or theoretical reasoning about how the low back MIGHT work. McGill presents only the highest level of empirical evidence available in the mountain of research on back function and disorder. Each claim is convincingly supported by rigorous research. In short, it’s an awesome contribution both to science and to back pain sufferers.
There is absolutely no comparison between the level of scientific merit in this work compared to anything one might read in the popular literature. Start by reading the free excerpt on Google Books. The following quotes explain why to avoid full spinal flexion so as to reduce risk of low back injury. (my emphasis in caps since html doesn’t seem to work. . .)
“…full flexion causes the interspinous ligament complex to strain, imposing an anterior shear force on the superior vertebra. For these reasons, avoiding full flexion not only ensures a lower shear load but also eliminates ligament damage.” (pp 136-137)
“A fully flexed spine is significantly compromised in its ability to withstand compressive load.” (137)
“Because herniation of the nucleus through the annulus is caused by repeated or prolonged full flexion, avoidance of the posture minimizes the risk of herniation (a cumulative trauma problem) and minimizes the stresses on any developing annular bulges.” (137)
[Note that virtually any lifter should be concerned about disc bulges progressing into a more painful and debilitating condition, because other studies show that most people have various degrees of injury to the discs.]
“Olympic lifters provide a convincing example of the efficacy of avoiding lumbar flexion in lifting. They lock their spines in a neutral posture and emphasize rotation about the hips.” (137)
“The important issue is not whether it is better to stoop lift or to squat lift; rather, the emphasis should be to place the load close to the body to reduce the reaction moment (and the subsequent extensor forces and resultant compressive joint loading) and to AVOID A FULLY FLEXED SPINE” (137).
Among the risk factors for low back disorders:
frequent torso motion
frequent lifting, pushing, and pulling
REPEATED FULL LUMBAR FLEXION
INCREASED SPINE MOBILITY (RANGE OF MOTION) (124-125)
Elaborating on the risk of range of motion, Marras (1993, 1995) found that increased spine range of motion increased the odds of low back disorder as much as ten TIMES. (Subjects wore a lumbar motion monitor, a three-dimensional goniometer that measures the three-dimensional kinematics of the lumbar spine.) Increased ROM was an independent factor, which means its tenfold risk remains after other risk factors are controlled. (127-128)
“…many of the classic instructions from “experts” about lifting (for example, bend the knees and not the back) are in most cases nonsense. In fact very few occupational lifting tasks can be performed this way…The science shows that squatting can have an increased physiological cost and that, depending on the characteristics of the load, it may not even reduce loads.” (133)
"Reducing pain and improving function for patients with low back pain involve two components:
Removing the stressors that create or exacerbate damage
Enhancing activities that build healthy supportive tissues" (133) [Note that this should be highly relevant to the OP in pain, who should definitely eliminate the stressor of spinal flexion, which strains the spinal ligaments.]
“Biering-Sorensen (1984) tested 449 men and 479 women for a variety of physical characteristics and showed that those with larger amounts of spine mobility had an increased occurrence of subsequent first-time back troubles. Luoto and colleagues (1995) reached similar conclusions.” (135)
“Should Workers Avoid End Range of Spine Motion During Exertion? [section heading] Generally, the answer to whether end range of motion should be avoided is yes—for several reasons. Maintaining a more neutrally lordotic spine will maximize shear support, ensure a high tolerance of the joint to withstand compressive forces, eliminate the risk of ligamentous damage since the ligaments remain unstrained, eliminate the risk of disc herniation since this is associated with a fully flexed spine, and qualitatively emulate the spine postures that Olympic lifters adopt to avoid injury.” (136)
Read only if you are interested.]