The pain is NOT where it hurts: why the LOWER BACK aches when the root sits in the hamstrings and hips
There is one kind of student who baffles a new teacher more than any other: a dull ache in the lower back, week after week of diligently stretching the back, arching the back, rubbing the back — and the pain sits there, stubborn, sometimes worse. You feel along the back muscles, press down the spine, and find nothing obviously "broken". The problem is not that you looked carelessly. The problem is that you were looking in the WRONG PLACE. In a great many cases of lower-back pain the culprit is not hiding in the back at all — it is lurking in the BACK OF THE THIGH and in the HIPS. This lesson opens Stage 2 with a shift in how you think as a professional: the body is a CHAIN, and the place you feel pain is usually only the link that is CARRYING the consequence, not the link that caused it. By the end, you will watch someone fold forward for a few seconds and start to guess where the root of their pain lies.
🎁 A gift from Tuấn Anh to teachers who want to master the craft.
The body is a chain — where it hurts is usually only where the consequence LANDS
Picture a blanket spread out flat. Pull hard on one corner and the opposite corner crumples — even though you never touched it. The human body works exactly the same way: muscle, tendon and bone are not separate parts but are joined by a wrapping tissue called fascia, like the white pith around a segment of orange. Tension at one end travels the length of the chain to the other.
- A way to feel the back chain for yourself: roll a small ball under the SOLE of one foot for a few minutes, then fold forward — many people find the BACK and the hamstrings suddenly give more. Foot and back never touch, yet both sit on one band of fascia down the back of the body. (This is a way of illustrating the fascial model so students can 'feel' the chain, not a clinical measurement.)
- It follows: a tight or painful spot in the lower back can be caused by a link FAR away — the hamstrings, even the calves.
What this gives you: this is the opening line that makes a class willing to believe you. Before you name a single muscle, let them feel 'force travelling' through their own foot.
The back of the body carries a near-continuous line of connection running from the heel all the way to the head: foot → calf → hamstrings → sacrotuberous ligament → spinal erectors in the back. These links follow one another mechanically, so tightness in a lower link will hold back and pull the upper link out of line.
- A multi-joint muscle is a 'force cable': the hamstrings bridge BOTH the hip joint and the knee. When they are short they do not merely lock the knee — they can drag the whole pelvis with them.
- What that looks like in practice: pinning the heels to the floor in a forward fold raises the tension all the way along the chain — proof that the chain is real and continuous.
What this gives you: when a student 'cannot reach their toes', do not jump to 'stiff back' — think of the whole back CABLE and hunt for the shortest link in it (usually the hamstrings).
This is the anatomical key to the entire lesson. Notice the paradox: the leg stays exactly where it is, yet the whole back changes shape. Why?
When the leg swings freely in the air (OPEN chain), the muscle contracts and the LEG moves. But when the foot is pinned to the ground (CLOSED chain), the muscle's lower attachment is locked in place. The muscle still contracts — but what moves is no longer the leg.
- So what moves instead? The pelvis and the spine above it. The muscle 'pulls upward' rather than 'pulls down'.
- This is precisely why the hamstrings or the hip flexors, sitting down in the thigh and hip, can govern the curve of the lower back.
What this gives you: understand this and you will not be surprised when 'freeing a muscle in the thigh' turns out to 'straighten the back'. A standing body is one closed-chain system.
Pull one corner of a blanket and the far corner wrinkles. The body is the same: force travels the chain, and the wrinkle — the pain — shows up where it piles up, not where it was pulled.
Before asking 'where does it hurt', a professional asks 'which link in the chain is pulling things out of line'.
The pelvis — the hinge that decides the curve of the lower back
Pelvic tilt is the pelvis rotating forward or back around the axis of the two hip joints. Picture the pelvis as a bowl holding water, resting on two balls (the heads of the thigh bones) — and because it rests on spheres, it tips in many directions very easily.
- Tipping FORWARD (anterior tilt): the front rim of the bowl spills forward → the lower back arches more deeply.
- Tipping BACK (posterior tilt): the front rim leans back → the lower back flattens and loses its curve.
What this gives you: every term needs one everyday sentence right behind it. 'Tipped back = flat back', 'tipped forward = arched back' — teach it with the bowl, not with Latin.
There is a healthy zone in the middle called the neutral pelvis — where the lower back holds its own natural curve. From there it strays two ways:
- NEUTRAL: a moderate lumbar curve, load spread evenly — the place we always want to bring a student back to.
- TIPPED BACK: the curve is gone, the back is flat.
- TIPPED FORWARD: an excessive arch ('swayback').
The hinge principle: a neutral pelvis makes a neutral spine possible, and the reverse — the two travel together, so setting one sets the other.
What this gives you: these three states are the simplest assessment chart you own. Everything else in this lesson is just answering: which state is the pelvis in, and which muscle put it there.
The pelvis does not move by itself in mid-air — the real movement happens at the hip joints (pelvis on thigh) and at the lumbar joints (pelvis on spine). Because the lower back plugs straight into the top of the pelvis, the moment the pelvis tips, the lumbar vertebrae are carried along with it.
- That is why we call the pelvis the HINGE: it is the joint that transmits movement between the body's two big halves — the legs and the trunk.
- 'Turn the hinge an inch out of true and the floor above it — the back — is a mile off.'
What this gives you: when you see a student straining to straighten the back while the pelvis stays tipped, remember — you cannot correct the curve of the back until you correct the tilt of the pelvis. Fixing the back and leaving the pelvis is fixing the branch, not the root.
The pelvis is a bowl of water set on two balls of thigh bone. Tip the bowl forward and the water spills forward; tip it back and it spills back. The lower back changes its curve in the same instant.
The pelvis is where force passes between the legs and the spine — read the direction of its tilt and you have read half the story of the pain.
Hamstrings pull BACK, psoas pulls FORWARD — the same back pain from two opposite roots
Start with the question: how does a muscle at the back of the thigh 'reach' as far as the lower back? The answer is in the attachment.
All three hamstrings share a root attachment at the SITTING BONE — the bony point at the lower-back corner of the pelvis, the very 'bone that meets the chair' when you sit. Because that root sits ON the pelvis, a hamstring that is chronically short and tight acts as a rein holding the sitting bone down and back. The chain of consequence:
- Step 1: the sitting bone is dragged → the pelvis rotates BACK (posterior tilt).
- Step 2: the lower back LOSES its natural curve, rounding and flattening.
- Step 3: the thoracolumbar fascia and the back muscles are stretched passively; at the same time the back muscles have to BRACE to compensate and hold things steady.
- Step 4: a rounded back pushes pressure towards the back of the disc → discomfort, soreness, sometimes a 'catch' or sharp twinge in the lower back.
The crux: the pain shows up in the BACK, but the force that caused it starts in the HAMSTRINGS and HIPS.
How to correct it: you see this one most in people who sit all day. Do not force the back straight — BEND THE KNEES to release the hamstrings' pull and free the lower back first.
The mirror image on the same hinge. The iliopsoas attaches along both sides of the lumbar vertebrae and the inner surface of the pelvis, passes over the front rim of the pelvis like a pulley, and runs on to the thigh. The rectus femoris attaches at the anterior inferior iliac spine (AIIS) — note the difference from the anterior SUPERIOR iliac spine (ASIS), which is where sartorius attaches. When these hip flexors are chronically shortened:
- They pull the FRONT of the pelvis down → the pelvis rotates FORWARD (anterior tilt).
- The lower back is arched too far (hyperlordosis, or 'swayback').
- The back surfaces of the lumbar vertebrae are compressed → which also produces LOWER-BACK PAIN.
The everyday cause: a day at a desk leaves the psoas short — and it is also a 'stress-reflex muscle', contracting when we are anxious.
An honest caveat: the 'over-arching causes pain' mechanism is asserted by many applied-anatomy texts; some more cautious authors say only that the psoas 'supports' the lower back. A teacher should present it as a mechanical loading tendency, not an absolute law.
How to correct it: an over-arched case needs no more back-bending; draw the tailbone down, lightly engage the lower abdomen to bring the pelvis back to neutral, and release the hip flexors at the front.
Which way the pelvis tilts is the outcome of a tug of war between two sides:
- The FRONT side (hip flexors): iliopsoas, rectus femoris — pulling the pelvis forward.
- The BACK side (hip extensors): gluteus maximus plus the hamstrings — pulling the pelvis back.
The two sides are each other's antagonists: when the back side extends the hip it lengthens the front side, and the reverse. With this map in hand, a teacher knows WHICH muscle to release in order to 'unlock' the pelvis back to neutral — without touching the back at all.
What this gives you: this is why a 'hip opener' (Pigeon, say, stretching the muscles around the back of the pelvis) eases recurring lower-back pain — it works on the SIDE that is pulling things out of line, not on the place that hurts.
Two students both report lower-back pain. One has a flat back because the hamstrings hold the pelvis tipped back; the other has an arched back because the hip flexors drag the pelvis forward. Give them the same practice and you treat one of them while harming the other.
Read the DIRECTION of the pelvic tilt before you prescribe anything — opposite roots call for opposite practices.
The sitting bone, the L5–S1 disc, and the idea of 'referred pain'
This is the core landmark of the lesson. The sitting bone is the bony point at the lower-back part of the pelvis — the spot you press down on when you sit up tall. All three hamstrings take their root attachment here (adductor magnus attaches right alongside, which is why it is called 'the fourth hamstring').
- Because that attachment sits ON the pelvis, the hamstrings have the leverage to tip the whole pelvic block — attached anywhere else they could not produce a posterior tilt at all.
- That is the anatomical evidence behind 'the root is in the thigh but it shows in the back'.
What this gives you: have students sit on their hands and feel their own two sitting bones — feel them 'roll backward' as the back rounds, and 'tip forward' as they sit up tall. That is the pelvis tilting.
The disc between the last lumbar vertebra (L5) and the sacrum (S1) sits right at the hinge joining the upper body to the pelvis, which makes it the single most common 'problem area'.
Picture the disc as a jam doughnut. When the spine FLEXES, rounding forward, the vertebral bodies tip forward and squeeze the jam towards the BACK — exactly the direction a disc most easily gives way.
- When tight hamstrings tip the pelvis back and round the lower back, that too is a form of flexion → load piles onto the back of the L5–S1 disc.
- The highest risk is moving into and out of a forward fold, not holding it still.
What this gives you: this is why 'keep the spine neutral' and 'bend the knees' are not fussiness — they are how you protect the disc from a dangerous direction of load. The integrity of the spine matters more than a straight leg.
Referred pain: pain FELT in one place while its SOURCE lies in another. The classic example: a chronically tight quadratus lumborum can send pain into the hip, the buttock and the lower back, even though it is itself a deep stabiliser of the lumbar region.
- The science underneath: how much pain we feel is NOT proportional to how much tissue damage shows on a scan. The brain constructs the experience of pain from how much danger the signals seem to represent — chronic pain is partly a story of 'an alarm system set too sensitive', but the pain is NOT imaginary.
- Do not confuse two movements: the sacroiliac (SI) joint also has 'nutation and counter-nutation' — a small nod of the sacrum alone — which usually happens ALONGSIDE a pelvic tilt but is NOT the same thing. For a teacher it is enough to keep them apart: pelvic tilt is the whole bowl moving; nutation is a small internal movement of the sacrum inside the bowl.
- Where the terminology ends: the hip–pelvis–back mechanics are agreed across the anatomy texts; the purely neurological part of 'referred pain' is handled with proper clinical terms in only some of the literature. Do not overstate it — say 'often' and 'tends to'.
What this gives you: the line that breaks the misunderstanding — 'where it hurts is not necessarily where it comes from'. That frees you to go looking for the real link instead of endlessly dressing the spot that complains.
The L5–S1 disc sits exactly at the hinge between the body's two big halves — and it takes a great deal of pressure when the hamstrings are tight. Saving a lower back sometimes has to start at the back of the thigh.
Where it hurts is where it shows, not necessarily where the damage is — the brain constructs pain out of the danger it reads into the signal.
Why 'just stretch the back' never ends the pain — and can make it worse
If the hamstrings are holding the pelvis tipped back, then your student's back muscles are already stretched passively and already bracing to compensate. Now you tell them to stretch the back some more:
- You slacken off a link that is already overloaded, while the ROOT pull from the hamstrings and hips is left exactly as it was.
- The pelvis stays wrongly tilted → the lower back still has no curve → load still piles in the wrong place. The pain has no reason to go anywhere.
What this gives you: explain it with this exact picture so students will give up the habit of 'stretch wherever it hurts' and accept working the hips and hamstrings — the part that looks as though it has nothing to do with the back.
Not merely useless — in many cases trying to 'stretch the back' with an extreme forward fold does damage:
- A maximal forward fold can overstretch the spinal erectors in the back.
- Extreme stretching can leave the sacroiliac (SI) joint uncomfortable, because the ligaments there do not readily return to their original length once they have been let out.
- Forcing flexion or twist through the lower back while the pelvis stays put is the familiar mechanism of disc strain.
What this gives you: this is the safety line — 'more flexible' is not always better. For someone whose joints are already loose, more stretch pushes them out of the healthy neutral zone.
The right handling is to intervene at the root link, working back up from the legs:
- Release the root: bend the knees to cut the hamstrings' pull and free the lower back. (If there is a twinge or a 'catch' in the back as they fold, bending the knees is the first reflex.)
- Reset the pelvis: actively bring it back to neutral, restoring the natural curve of the lower back.
- Only then lengthen: once the frame is right, build the hamstring stretch up safely and gradually.
The counterbalance rule: after a pose that shortens the hip flexors (Boat, for instance), follow it with a hip opener — so no muscle is left sitting in a shortened, off-line state.
What this gives you: hold on to the formula 'release the root → reset the pelvis → then lengthen'. That is the safe correction for almost every lower-back case that comes from the hip–hamstring chain.
A month of stretching the back and no relief — because you have been watering the branch while the root goes dry at the hip.
The pain is in the back, but the lever that corrects it sits in the HIPS and HAMSTRINGS. Treat the root first; do not slacken off a link that is already bracing to compensate.
Reading the WHOLE hip–pelvis–back chain: a 3-step checklist and a self-check for class
Move from 'point of pain' thinking to 'chain of force' thinking with one quick routine:
- Step 1 — Read the direction of the pelvic tilt: have the student stand side-on and look: is the pelvis tipped FORWARD (arched back) or BACK (flat back)? You can feel for the iliac crest or the sitting bones to confirm.
- Step 2 — Test both sides: check the hamstring tension (a forward fold, or a straight-leg raise) and the shortness of the hip flexors (try extending the hip backwards). Whichever side is shorter is the side pulling the pelvis out of line.
- Step 3 — Intervene at the RIGHT root link: root in the hamstrings (pelvis tipped back) → release the hamstrings and bend the knees; root in the hip flexors (pelvis tipped forward) → back to neutral and release psoas and quadriceps. Never prescribe the same practice for two opposite roots.
What this gives you: a pocket assessment chart, so you never 'treat the spot that hurts' again.
A 30-second experiment that turns the theory into a trained eye:
- Have the student stand and fold forward, arms hanging down.
- You watch: which way does the pelvis — the two sitting bones — tilt? If the sitting bones 'refuse to tip up' and the back rounds early → the hamstrings are holding on, and the pelvis is locked in a posterior tilt.
- Ask them to bend the knees slightly — if the sitting bones immediately tip up and the back lengthens, you have just confirmed that the ROOT is in the hamstrings, not in the back.
What this gives you: run this with enough students and within a few sessions you will 'read' the position of a pelvis in seconds — exactly what Stage 2 promised.
The last tools for working safely on the pelvic hinge:
- Stretch in the right place: the sensation of lengthening belongs in the MIDDLE of the muscle belly, not near the joint or the attachment. A sting, a twinge or numbness near the joint is a sign of OVER-STRETCHING and harms ligament and tendon → come out a little, or bend the knees at once.
- Hold neutral with the deep core: draw the tailbone down and lightly engage the lower abdominals (transverse abdominis) to support the lower back — 'neither round it nor over-arch it'.
- Come out of a fold at the HIP HINGE: push the hips back, keep the back long, hold the core — instead of curling up one vertebra at a time. That takes load off the lower back.
What this gives you: a painful or weak lower back is usually a problem of the hip–abdominal stabilising GROUP, not of the back muscles alone. Building the deep core is the safety brake for the whole chain.
A good teacher does not ask 'where does it hurt' but 'which link in the chain has failed'. Read the whole cable, not one point on it.
The pelvis is the body's mechanical crossroads; back pain is usually the downstream consequence of pelvis and hip alignment going wrong upstream.
You now hold the map of the hip–pelvis–back CHAIN and can read the tilt of a pelvis in seconds. But that is only the overview map. In the next lesson we zoom in on the number-one 'culprit' link — the HAMSTRINGS: why they shorten, why bending the knees 'rescues' the whole spine, and how to lengthen them without pulling on the lower back or the SI joint instead. Master one link and you can correct a group of cases. Master the whole chain and you become the teacher every student with a sore back wants to find.
To unlock Lesson 9
Answer all three correctly to unlock Lesson 9.
1. What are the four walls of the “core canister”?
2. On the IN-BREATH, how do the diaphragm and the pelvic floor move?
3. Engaging the core PROPERLY means:
The road — 31 lessons · 4 stages
You are on Lesson 8. Each lesson opens one real question about the body — understand it, and you practise & teach that much more soundly.
- 1The spine — the axis of all movementAvailable
- 2The six directions the spine movesAvailable
- 3Which muscles each spinal direction uses (SHORTENING ↔ LENGTHENING)Available
- 4Why years of practice still won't get you into the lotus (tension vs compression)Available
- 5Every joint its own kind of hinge (bone – joint – cartilage – ligament)Available
- 6Muscle, tendon, fascia: the factory that makes & transmits forceAvailable
- 7Does stretching really make a muscle "longer"?Available
- 8The core is an "inflatable corset" — breath · diaphragm · pelvic floorAvailable
- 9One shape at the foot frees the shoulder (fascia)Available
- 10Why one cue produces a different shape in every bodyAvailable
- 11Reading the body as a system of forces (putting it together)Available
Student A has lower-back pain. Standing, the back looks fairly FLAT; folding forward, the back rounds very early and does not reach far. Where does the root of the problem most likely lie?