A Review of Stuart McGill's "Low Back Disorders" - Part 1

In an effort to resolve my own chronic back issues once and for all, I am making the effort to read -- and try to really understand -- Stuart McGill's "Low Back Disorders: Evidence-Based Prevention and Rehabilitation." This review is an effort to very concisely summarize some points that he makes in the book. The book is intended for professional clinicians, which I am not. I will try to summarize in the least technical terms possible the points that are helping me to shift how I think about my back and how I can get to a permanent pain-free situation; one where I don't have to worry about my back giving out every time I head out on some little trip. I encourage anyone who is actually working through their own back pain to consult the original source, it's entirely possible that I've completely misunderstood entire portions of the book.

Parts 1 & 2

The book is divided into three Parts: 1 - The Scientific Foundation, 2 - Injury Prevention, and 3 - Low Back Rehabilitation. I'm still working through Part 3, so this review only covers the scientific foundation and injury prevention. I know, if you're reading this all you really want o know is what to do, but I haven't gotten there yet. The first two parts are164 pages long. I took 8.5 pages of notes in very small print, so obviously I'm leaving alot out.

1 - Most chronic low back pain issues are not the result of a single traumatic incident (unless of course they are the result of, say, a snowmobile accident (see first image), or a fall from height which applies a very high load in a single event); they are the result of "cumulative trauma pathways." This is either the repeated application of a low load (ex, repetitively flexing the spine while picking light objects up off the floor; see second image) or a sustained load for long duration (ex, slouching while sitting at a computer or a carpenter constantly bending over to put nails in a floor; see third image). These loads are typically well below what people believe is damaging to the spine but repeated or prolonged exposure is indeed damaging. So, even though I typically can pinpoint an incident where I 'tweaked my back,' it is more likely that the hours of sitting slouched at work and poor control of lumbar flexion in other everyday tasks is the real culprit. These are the low-level loads that permit me to 'tweak' my back.

2 - Using the "core" musculature (extensors, anterior abdominals, and lateral abdominals along with a bunch of other supportive tissues, like the lumbodorsal facia, is discussed) to lock the rib cage onto the pelvis supports the spine in a neutral position is key to reducing loads on the spine during all everyday tasks from getting out of bed to opening a door to picking up a pencil off the floor.

3 - Interestingly, muscle endurance (NOT strength) and lower (NOT larger) range of motion is protective of the spine. So, even though it's common to think, "I need to be stronger and more flexible," you really need to be more precise. You don't need strength so much as you need endurance in your stabilizing core muscles so that they can maintain the low-level contractions necessary for stabilizing the lumbar spine in all of your everyday tasks; from opening doors to tying your shoes to shoveling snow. Further, more flexibility in the lumbar spine makes you MORE likely to get injured. Now, it might be that you need to increase flexibility in the hip (say, the hamstrings or psoas), but you need to stretch those muscles correctly; which is to say, keeping the spine neutral and being conscious to not accidentally stretch the lumbar extensors. This error is particularly common in the toe-touch type of hamstring stretches, where you bend over (or sit) and touch your toes. This is stretching your extensors more than your hamstrings and exacerbating instability issues in the lumbar spine.

4 - I've already commented on how poor motor control can lead to spine buckling and injury, even when picking up very light objects.

5 - McGill encourages you to think about your spine this way: it's a fishing rod with the reel end on the ground (this is the flimsy flexible spine itself) supported by guy wires that allow it to support a load (the guy wires are the anterior, lateral, and posterior musculature that, when stiff, permits the spine to bear massive loads. The key points: 1 - without stiffened (slightly taught) musculature, the spine is flimsy and flexible under even the most modest loads (few pounds); and 2 - if any of the guy wires are more or less tight than the others, this will lead to instability so all the muscles must work together.

6 - Spinal flexion early in the morning should be carefully avoided. The spine lengthens while you sleep overnight because the spinal loads are lower than the osmotic pressure, therefore the discs fill with fluid. These engorged discs greatly increase the pressure of any flexion in the morning, so absolutely no flexion stretches in the morning (no toe touches, no bringing your knees to your chest, etc) and be very careful when putting on your socks and tying your shoes.

7 - Sciatica symptoms are the result of nerve irritation. Therapy is two-fold: 1 - avoid end ROM in the spine, and 2 - perform "nerve flossing." There's a demo here, but I can't verify that is done absolutely perfectly, but that's the general idea. If you have sciatica, best to review this with you PT, and not rely on a blog or youtube.

8 - It is useful to remember that muscles and other soft tissues are not rigid and static but creep (slowly elongate when under load) and have more viscoelastic properties. This comes up several times in the discussion of herniated discs and how the nucleus of the spinal discs can 'migrate' or flow depending on the posture of the spine. In diagrams, the nucleus is typically shown in the middle of the annulus, but it's useful (if not completely technically accurate) to think about the nucleus moving closer to the edge of the annulus in response to repeated flexion (or extension) or prolonged flexion (or extension). When the nucleus is off-center and then full range of motion flexion/extension or large loads combined with flexion/extension are performed, it is much more likely to result in a herniated disc. Best to give the disc a few minutes to equilibrate while in a neutral posture before beginning to load it. This comes up again and again. It also affects the order in which rehabilitation exercises are performed, so it's an important concept that requires more detail than I can provide here.

9 - Some specific advice for preventing low back disorders:

a - avoid end ROM in the spine, keep it neutral;

b - reduce the reaction moment on the spine by keeping loads close to the body, directing force vectors through, or around, the lumbar spine, and simply reducing the weight or load itself;

c - avoid exertion after prolonged flexion (ex, immediately picking and moving boxes after sitting for awhile, instead stand-up, move around for a few minutes first, then begin exertion);

d - avoid high torques on twisted spines (note that significant torque should only be applied to neutral spine);

e - use momentum properly to reduce loads (note that slow and smooth isn't always the best way to spare the spine);

f - make seated work less demanding on the spine by constantly changing positions (there is no "perfect sitting posture"!), get out of the chair as often as possible (maybe every time the phone rings?), and get a little exercise in the middle of the workday;

g - Limit flexion early in the morning;

h - do as much variety as possible, repetitive work, even at low loads, can be very damaging over the long term;

i - co-contract the lower back and abdominal musculature to stabilize the spine even with very light loads.

10 - In general, workers should not wear any sort of lumbar back support. There's a whole chapter on this, if you really want to know why, check out the book. It's clearly stated and the supporting evidence is convincing (to me, anyway).

11 - During all daily activities and especially during rehabilitation exercises, prevent pain first. The pain is the result of injury and continuing to irritate the tissues causing the tissues to sensitize to even very minor irritation. In addition, the pain results in an entire series of cascading issues that basically makes gives your back a "limp." This "limping back" ingrains poor motion and muscle activation patterns that will prolong back pain and limit recovery and rehabilitation. Never work through the pain. This is not a "No Pain, No Gain" problem. Eliminate the pain first. Only work through a ROM that is pain-free. Always.

IMAGES: All the images above were photographed from Stuart McGill's "Low Back Disorders: Evidenced Based Prevention and Rehabilition" 2nd edition. They are provided here without permmission but with full credit.