Back Pain Relief & Spine Anatomy | Dr. Stuart McGill & Dr. Andrew Huberman
00:00:00.000 | Okay, so I'm standing here with Dr. Stuart McGill, who's an expert in the back, back
00:00:08.180 | strengthening and relief of back pain.
00:00:11.700 | And he's going to tell us about the structure of the back in terms of where it derives its
00:00:15.740 | stability from, where pain can arise, and various routes by which to relieve that pain.
00:00:21.700 | So why don't you explain to us what you're holding here.
00:00:25.500 | It looks like an anatomical model of a piece of the spine, spinal cord and pelvis.
00:00:32.100 | That's just about it, professor.
00:00:35.220 | If I was to align this on yourself, that's where it sits.
00:00:38.200 | So there's your pelvic ring.
00:00:41.460 | There's joints called the sacroiliac joints from behind, where when a person does a split
00:00:48.740 | lunge, for example, one side mutates forward, the other side mutates back, and you can see
00:00:54.060 | the micro movements that occur in the sacroiliac region, which may be healthy, or they may
00:01:00.600 | cause pain.
00:01:01.760 | So those are fairly small movements.
00:01:03.180 | So they look like they're on the order of millimeters.
00:01:05.180 | Is that right?
00:01:06.180 | About a half a millimeter.
00:01:07.180 | Okay, so tiny movements.
00:01:08.780 | They're micro movements that, as I said, could cause symptoms or they indicate good health.
00:01:19.660 | This creates a platform for the lumbar spine.
00:01:23.040 | So as it's orientated this way, if you were to pick something up, the force is supported
00:01:31.620 | down this middle of your body through the spine.
00:01:34.060 | So it needs a platform to be supported by.
00:01:39.360 | So you can imagine, I'll just place it on me, if I was going to stand on one leg, the
00:01:44.820 | force is driven down the center of my torso, but then it has to shear across to the support
00:01:51.420 | leg.
00:01:52.420 | So the tendency of the spine is to bend like that.
00:01:55.620 | So now you see the importance of the lateral muscles on this side to hold the pelvic platform
00:02:02.020 | up and then the hip muscles on this side to start, you see my hip is trying to collapse
00:02:08.000 | because of gravity.
00:02:09.500 | So there's a lot of moving parts in how all of this works.
00:02:13.500 | So as far as the spine goes itself, you know, the hips are ball and socket joints, but the
00:02:19.660 | joints of the spine are actually what we would call an adaptable biologic fabric.
00:02:25.980 | So just as my shirt has fibers, these have fibers of collagen layer upon layer, which
00:02:32.740 | allow movement to occur, but they also apply or provide stiffness so that the spine is
00:02:42.500 | inherently stable for very small loads because it has discs.
00:02:47.500 | So we have the vertebral segments and then the discs in between them.
00:02:50.700 | And then what people see here are the nerve roots emanating from the spinal cord.
00:02:54.420 | Right.
00:02:55.420 | The spinal cord starts in the base of your skull and goes down the middle of the spine
00:03:01.300 | through what's called the magnum foramen, the big hole down the middle.
00:03:05.780 | And at each level where there's a disc, there's a pair of nerve roots that come out laterally
00:03:12.340 | to serve different parts of your body.
00:03:14.900 | So if this nerve was compromised here, that's the fourth root on the left hand side.
00:03:20.660 | This goes around behind your hip joint, down your hamstring, down your calf and serves
00:03:27.200 | the small four toes.
00:03:29.460 | So if you had irritation by bending your spine a certain way and said, well, my little toes
00:03:34.340 | just went numb, we would know with some precision that that's the culprit that with that precision,
00:03:40.220 | that nerve right there.
00:03:42.140 | What are some of the sources of impingement on that nerve?
00:03:45.420 | I could imagine the disc bulging at this location is one potential source.
00:03:50.580 | I could imagine a shearing motion that would put it in contact with some of the bony elements
00:03:57.060 | in here.
00:03:59.140 | What are some other sources of impingement on the nerve?
00:04:01.540 | Well, exactly those two.
00:04:02.540 | Let me demonstrate.
00:04:03.540 | We're just going to do a do-si-do there with the two models.
00:04:06.200 | So this is a more detailed anatomical model of just one segment.
00:04:10.500 | You'll notice that the spinal cord traverses up and down.
00:04:14.540 | So as you look down, it migrates the cord cranially.
00:04:20.540 | So it's pulling the spinal cord up and because it actually laces through these bony elements,
00:04:28.100 | the spinal cord is literally sliding up.
00:04:31.060 | It is.
00:04:32.060 | And if you were to kick forward with one leg through the hip with a straight knee, it would
00:04:36.300 | do the opposite.
00:04:37.300 | It would pull the cord that way.
00:04:39.380 | But now look at the migration and the mechanics of the nerve roots.
00:04:43.180 | This is sliding up and down about two centimeters or for my American colleagues just over, well,
00:04:49.500 | getting close to an inch.
00:04:51.220 | So it's quite a distance, quite a translation.
00:04:57.460 | You can imagine now if something was rubbing that nerve root, it would irritate it with
00:05:01.980 | the motion.
00:05:02.980 | So your question was, what are the candidates?
00:05:04.940 | Well, when a person is younger and if they get a disc bulge, we're just going to show
00:05:10.420 | a disc bulge here, inside the disc is a nucleus which is gel.
00:05:17.740 | It's a very thick gel.
00:05:20.180 | And when you squeeze the spine or I bend and pick up an object, we put compressive load
00:05:27.140 | onto the disc.
00:05:28.900 | And if we're stacked nice and tall, you'll see the disc sees the compression as you can
00:05:33.700 | imagine it would in a very sort of a shock-absorbing manner.
00:05:38.140 | But now I'm going to bend the spine forward and squeeze.
00:05:42.460 | Do you see there was a delamination or a little bit of a damage and delamination of the fibers
00:05:48.740 | that we described earlier, they separate as the person bends forward and then the squeezing
00:05:54.880 | pressure creates a hydraulic effort through the delamination and you see the disc bulge
00:06:01.860 | just starting to occur with the nuclear gel.
00:06:06.540 | And then as the person keeps moving in excess, now if you just move, we did a study on belly
00:06:13.200 | dancers who have tremendous gyrations in their spine, that didn't create delaminating stresses
00:06:19.180 | because there was no large compressive load.
00:06:22.020 | So motion for the spine without load is not particularly a bad thing.
00:06:26.360 | But when you add compressive load, now you've pressurized the nucleus and it's pushing
00:06:31.700 | from behind those fibers.
00:06:33.780 | So now you're bulging them out a little bit.
00:06:35.680 | Now you can start to see how they'll separate.
00:06:38.340 | And if my thumb is the gel, it's seeking the crack to come through.
00:06:44.140 | And then that creates the disc bulge, which is a combination of motion, usually bending
00:06:48.980 | forward with compression.
00:06:51.200 | And on a previous episode that I did about back strengthening, I mistakenly said that
00:06:56.060 | the spinal cord threads through a compartment in the disc.
00:06:59.460 | It does not.
00:07:00.460 | We corrected that.
00:07:01.460 | I should say in the show note caption, the spinal cord is posterior to the disc, correct?
00:07:06.980 | - Correct.
00:07:07.980 | - And does not course through it, but is just adjacent to it.
00:07:12.060 | And the disc is however, in a position to impinge on these nerve roots if it gets extruded.
00:07:18.500 | And in some cases to push the nerve root against some of the bony elements causing what we
00:07:24.200 | call pain, right?
00:07:25.420 | But the pain doesn't necessarily occur at the level of the root.
00:07:28.660 | It can occur at the level of innervation or further down the neural pathway.
00:07:32.580 | - The pain can go wherever the nerve root goes, exactly correct.
00:07:36.320 | So now if we start to move the nerve, the central spinal cord or at this level, it's
00:07:42.260 | called the cauda equina, it separates into separate roots.
00:07:45.060 | But nonetheless, do you see how that root now moves as a function of your hip motion
00:07:51.420 | and your neck motion?
00:07:53.060 | So now you're frictioning the nerve past the mechanical offense.
00:07:57.580 | So it creates varying types of local pain and radiating pain as well.
00:08:03.780 | - So if there is a disc bulge and it's impinging or somehow otherwise causing pain by compressing
00:08:11.700 | one of these roots, irritating one of those roots as it were, what can be done to return
00:08:18.580 | some of that bulge back into its proper location?
00:08:23.700 | - Avoid bending the spine forward, which is the primary driver of causing that disc bulge
00:08:28.700 | to grow.
00:08:29.700 | Now, not of every disc bulge.
00:08:33.340 | It tends to work better in younger people.
00:08:36.000 | So I'm just going to slide my hands down my thighs, but notice I'm flexing at the hip.
00:08:41.180 | I'm not flexing through the spine.
00:08:43.660 | If you can flex at the hip, and here might be a therapy, if I just grab my knees hard
00:08:51.460 | and then I shape the curvature of my spine, then I push my toes down and I become a leaning
00:08:57.420 | forward over my ankles, and now I anti-shrug.
00:09:00.020 | Do you see what I did, Andrew?
00:09:01.620 | I carry more weight.
00:09:02.700 | I'm showing you my triceps.
00:09:05.640 | If I organize that right, that can actually be a disc bulge reducing procedure.
00:09:12.220 | - Interesting, because when I had this L4 disc bulge, the suggestion to me was to do
00:09:17.620 | cobra pose or something similar, to lie down on the floor, point my toes out, so toes and
00:09:26.100 | tops of feet and legs are in contact with the ground, and then to push up and essentially
00:09:31.700 | to arch the spine, and then to repeat that, 10 or so cobra push-ups, as it were, and then
00:09:37.560 | to hold the final one for maybe 30 to 60 seconds, and then to get up and return about my day
00:09:44.420 | and to do that several times, and it worked fabulously well.
00:09:48.020 | - That works fabulously well for certain types of disc bulges.
00:09:52.180 | We did experiments on this, and if the disc original height or 70% of that height or more
00:09:59.180 | is remaining, that works very well.
00:10:01.460 | If you flatten the disc so it's lost, it's about 60% or less of its retaining height,
00:10:07.500 | that won't work.
00:10:08.500 | In fact, that will probably cause more pain, so that, it's called the McKenzie prone press-up
00:10:14.780 | or the cobra pose, can be very effective with the rider of how much disc height is remaining.
00:10:21.700 | But another concern occurs.
00:10:24.380 | Some people think, "Well, that was an effective therapy for that disc bulge for two weeks.
00:10:29.340 | I'm going to do it every day for the next year."
00:10:31.380 | Now we run into a problem.
00:10:32.540 | The disc is now a little bit flatter.
00:10:34.880 | These facet joints on the back are two articulating joints.
00:10:40.140 | There's the motion that they're undergoing during the floppy push-up, as it's called.
00:10:45.680 | - The cobra push-up.
00:10:46.680 | - The cobra push-up.
00:10:48.280 | Because the disc is now lost height, you've now biomechanically transferred much higher
00:10:53.180 | load to those facet joints, and they become irritated.
00:10:56.640 | So before, bending forward under load caused your pain in the disc bulge to grow, but now
00:11:02.280 | bending back causes pain from the facet joints, which is another distinctive pain.
00:11:07.920 | We can arch back, drop one shoulder back, and, oh, yeah, you can feel that local ache
00:11:14.280 | there.
00:11:15.280 | So those are a couple of issues to be aware of.
00:11:18.880 | We did another experiment where we mimicked the floppy push-up versus simply holding it
00:11:25.320 | isometrically.
00:11:27.640 | And the isometric pose doesn't cause the movement irritation of the facet joints.
00:11:33.480 | In terms of returning the disc bulge, it was just as effective.
00:11:36.960 | But following the same guideline again, 70% of the original disc height must be remaining
00:11:46.020 | for the isometric to work.
00:11:49.320 | So there's some guidelines for you to make that exercise even more effective.
00:11:55.140 | But you asked, what else could impinge on a nerve root?
00:11:58.600 | Over time, as the disc becomes damaged, you now get more motion, and this is what we call
00:12:07.640 | an unstable joint.
00:12:09.960 | That causes more load on the facet joints.
00:12:11.920 | So let's do our do-si-do one more time.
00:12:15.240 | And this model has been prepared that this disc, the fourth lumbar four, is damaged.
00:12:23.160 | L5 is normal, L3 is normal.
00:12:25.960 | This is the joint that has lost stiffness.
00:12:28.400 | Now people hear the word stiffness, and they think that's a bad thing.
00:12:31.740 | But a joint has to have a certain amount of stiffness to provide support and define the
00:12:38.440 | range of motion.
00:12:40.000 | So remember, this is the damaged joint.
00:12:42.320 | I'm just going to apply a general torque above.
00:12:46.080 | And you see how the majority, the overwhelming majority of the motion is occurring at the
00:12:50.260 | damaged joint.
00:12:51.800 | Not at the one above and not at the one below.
00:12:54.200 | Now let's turn around and look at the facet joints.
00:12:56.760 | They've been painted red.
00:12:58.300 | Those are the joints that are working because of the disc damage.
00:13:02.880 | So when we turn a little bit, we get a little bit of shearing motion.
00:13:06.160 | If we turn a lot, that joint, that facet joint on the compressive side is overloaded, and
00:13:12.240 | that causes the whole upper vertebra to slide across.
00:13:16.020 | Over time, that's going to encourage arthritic bone growth just at that level.
00:13:21.820 | So another mechanism for the impingement on that nerve root is bone growth around the
00:13:28.900 | facet joint, which will make the hole even smaller.
00:13:32.360 | So there's another source of pain.
00:13:34.980 | The moral of the story is keep your discs as healthy as you can, and you'll have a better
00:13:40.360 | life.
00:13:41.360 | Well, that's okay.
00:13:46.400 | So are there ever cases where one would want to attempt to return the disc to its proper
00:13:53.480 | compartment?
00:13:54.480 | In other words, to reverse or reduce the bulging of a disc where the proper movement would
00:13:59.720 | be the opposite of a Cobra push-up, where it would actually involve abdominal work in
00:14:03.840 | order to try and work back in the disc from the other direction, so to speak?
00:14:11.080 | Yeah.
00:14:12.080 | "It depends," is the answer.
00:14:14.280 | There's a real nuance to all of this.
00:14:15.840 | So that's why we spend so much time on the assessment to define the precise nature of
00:14:21.000 | the disc bulge.
00:14:22.000 | And I should just mention that in the episode that we recorded with you, which we provide
00:14:25.920 | a link to in the show note captions, you described some of the assessment questions, self-assessment
00:14:31.440 | questions.
00:14:32.440 | We talked about "Back Mechanic," your book, which fabulously describes some ways to self-assess
00:14:36.440 | and remedy, as well as a link to some of the clinicians that you've trained in the precise
00:14:41.800 | methods based on much of the work that you and others have done to address these problems
00:14:47.280 | specifically.
00:14:49.280 | Said long-winded, because as Dr. Stuart McGill has pointed out many times, the sources of
00:14:55.140 | back pain are many and varied, and the relief for back pain is both highly individual and
00:15:04.760 | involves varied techniques, depending on the nature of the injury or the nature of the
00:15:09.760 | pain.
00:15:11.080 | And there are a number of other factors, psychosocial, emotional, et cetera, that are also important.
00:15:17.240 | And we describe all...
00:15:18.240 | I should say Dr. Stuart McGill describes all of those in the episode linked in the show
00:15:21.920 | note caption.
00:15:22.920 | Yeah.
00:15:23.920 | There's a time for surgery and a very specific type of surgery.
00:15:26.940 | There's a time for a very specific type of exercise, be it mobility, stability, or whatever.
00:15:32.880 | There's a time for pretty much everything.
00:15:34.500 | The key is to match it to the...
00:15:38.840 | I don't want to say injury, but it could be an injury.
00:15:42.480 | It could be a sensitivity, et cetera.
00:15:45.240 | But anyway, going back to this idea of there being a...
00:15:49.960 | That is now called a clinical instability that you can see.
00:15:53.640 | If you could arrest that joint and restore its motion, so when you twist, the whole unit
00:16:00.680 | doesn't see the shearing joints, you do that through abdominal contraction.
00:16:06.080 | So if I cued you and said, "Andrew, push my fingers out," yes.
00:16:11.160 | Don't push your belly forward if you can.
00:16:13.840 | Try and flare your oblique muscles out laterally.
00:16:16.920 | That's the pattern.
00:16:18.240 | And that will then arrest that micromovement and some people will...
00:16:22.120 | That will say it takes their pain away.
00:16:24.560 | Is there ever a time to flex forward to deal with the disc bulge?
00:16:28.360 | And the answer is yes.
00:16:30.400 | The type of disc bulge that when you bend forward and the disc bulge is on the back
00:16:36.200 | of the disc is typical of a weight training kind of injury.
00:16:40.760 | If you had someone with a very flexible spine, they don't lift weights, but they do lots
00:16:46.080 | of yoga.
00:16:47.080 | Backbends.
00:16:48.080 | They've adapted their spine for mobility, not for load bearing.
00:16:52.160 | So the collagen and the ground matrix between the fibers have become very soft.
00:16:58.640 | So whereas someone who was strength training, when they squeeze and bend forward, the disc
00:17:05.720 | bulge comes out posteriorly, someone with very soft constituency to the disc, it bulges
00:17:13.560 | on the front.
00:17:14.960 | So it's a different type of bulge.
00:17:17.360 | So it depends on how you've adapted your spine as to whether flexion will help you or extension.
00:17:22.620 | So again, knowing with some precision, the mechanism of the pain or disorder allows you
00:17:28.240 | to match the intervention.
00:17:29.840 | Fantastic.
00:17:30.840 | Well, this has been a wonderful description of spinal and pelvic anatomy discs and a very
00:17:36.680 | dynamic structure and yet a very stable structure in its best configuration.
00:17:40.720 | What amazes my students is when I hand them a spine and I get them to with all their strength,
00:17:45.920 | try and bend it and break it.
00:17:47.320 | They can't.
00:17:48.320 | So it's incredibly robust.
00:17:50.120 | But the things that we do to ourselves, creating long levers and doing what we do creates tremendous
00:18:02.380 | internal stress concentrations beyond what you could ever apply with your hands.
00:18:07.280 | All the more reason to do the McGill Big Three on a regular basis that was also described
00:18:12.860 | and demonstrated in some other videos that we provide in the show note captions.
00:18:18.300 | And of course, please be sure to check out the full length interview with Dr. Stuart
00:18:22.400 | McGill in which he describes in beautiful and immensely clear detail the structure and
00:18:28.800 | function of the spine and back, how to strengthen your back, how to get rid of back pain and
00:18:34.040 | how to stave off back pain, not just after an injury, but your entire life.
00:18:39.600 | And by the way, at this moment, he is 67 years old.
00:18:42.440 | He's in awesome shape and an inspiration to me and anyone watching, I'm sure is equally
00:18:47.640 | impressed that he puts in the work on a regular basis.
00:18:50.640 | And in that episode, he also describes his so-called biblical schedule, which is six
00:18:54.700 | days a week of fairly limited in duration training geared toward cardiovascular fitness,
00:19:01.440 | strength and mobility.
00:19:02.960 | It also includes a full day of rest.
00:19:04.720 | [Music]