One cue, a different shape in every body — why your skeleton is the real 'template'
Picture a class of twelve. You give exactly ONE instruction: 'sit cross-legged, let both knees drop towards the floor.' Then you look round the room — and see twelve completely different ways of sitting. One person's knees rest on the floor as lightly as if they had been laid there. Another's knees hover up at belly height, their face already red with effort. The same cue, everyone 'doing it right', and the outcomes a world apart.
Most teachers' first reflex is to blame themselves — 'where did I cue that wrong?' — or to blame the student: 'they're not trying, they're not flexible enough.' Both are wrong. The anatomical truth is blunter: there is no such thing as 'one correct shape' for everybody, because there is no such thing as 'one standard skeleton'. Each person has their own shape of hip socket, their own angle of femoral torsion, their own kind of vertebrae, their own ratio of arm to leg to torso — and those inborn differences FORCE one cue to produce different final shapes. This is a physical impossibility, not a failure of effort.
This lesson takes you from the big picture — 'bone shapes the form; there is no common template' — down to the specific figures, and then hands you the most important professional tool of all: how to tell whether a student is stopping because of MUSCLE (trainable, keep going) or because of BONE (you have arrived; stop). By the end you will stop forcing a whole room into one magazine shape — and start teaching the body in front of you. Don't be daunted by the scientific names; we go step by step, and everything is testable in your own body right now.
🎁 A gift from Tuấn Anh to teachers who want to master the craft.
Bone shapes the final form — there is no one correct shape for everybody
[REMEMBER] One single principle governs this whole lesson: the shape of a joint reflects its function. The body does not design every joint the same way — each is 'moulded' for a different job:
- The hip = a ball-and-socket joint → prioritising a large range, rotating in many directions.
- The knee = a hinge joint → prioritising stability, mainly flexing and extending, with very little rotation.
- The intervertebral joints → each vertebra allows only a very small movement, to protect the cord; the suppleness of the whole spine is the SUM of many small movements added together.
The key point: it is not only that each joint differs — each SKELETON differs from person to person. Because the shape of the bone decides the range, and the shape of the bone differs from birth, one cue inevitably produces different final shapes. There is no 'standard skeleton', so there can be no 'one correct shape for everybody'.
What this gives you: this is the statement to pin on your studio wall. When you see twelve different shapes, don't ask 'who is doing it wrong' — understand that these are twelve skeletons expressing the same function in their own way.
[REMEMBER] The greatest misunderstanding in yoga: 'anyone can get into the standard shape just like the photo if they practise hard enough.' This is a physical impossibility, not a matter of willpower.
- The photograph in the magazine is only ONE particular skeleton — that model's own — photographed from exactly the flattering angle.
- Forcing a differently built body into that same shape is not 'progress' but trading sound structure for a few meaningless degrees, and it injures very easily.
- The 'correct' shape = the shape that suits the structure of the person actually practising, achieving the FUNCTION of the shape (stretching or strengthening the right area) rather than copying an outward form.
[GRASP THIS] Some people will never get both knees to the floor in a cross-legged seat — and that is entirely fine. They are not inferior, and you are not teaching badly. It is simply the shape of their hip socket.
What this gives you to correct: stop using the model photograph as an obligatory destination. Change 'you must get down like this' into 'find the point where this area feels just enough tension'.
The UNIQUE shape of your bones and joints decides what your shape LOOKS like — and it differs for everybody.
Two kinds of limit: a HARD stop (bone) vs a SOFT stop (muscle)
[REMEMBER] This is the most important professional tool in the whole lesson. Every range is blocked by one of two kinds:
- A HARD STOP — caused by BONE. Bone meeting bone (or bone meeting tissue). Its signature: almost NO stretching sensation, only a sudden 'jam', 'block' or 'contact' right in the direction you are trying to go. It never changes however long you practise — yoga does not alter the shape of bone.
- A SOFT STOP — caused by MUSCLE or soft tissue. Muscular tightness limiting it. Its signature: a clear pulling, stretching sensation in the middle of the muscle belly, on the side OPPOSITE to the direction of movement. It improves gradually with practice.
The golden way to tell them apart: a PULL on the side OPPOSITE the movement = MUSCLE (trainable); a CONTACT or JAM right in the direction you are MOVING = BONE (stop). One simple question changes how you teach.
What this gives you: confusing these two is the number one reason teachers unwittingly push students into injury. Taking bony compression for 'tight muscle that will open if I press harder' → destroys the joint cartilage.
[GRASP THIS] Not every 'stop' is caused by bone. What to hold, in two halves:
- A stop caused by MUSCLE or SOFT TISSUE (tight adductors, tight hamstrings, even flesh pressing against flesh in a deep knee bend): the stretching sensation is still there, and it can be opened up gradually with safe practice.
- A stop caused by BONE meeting BONE: this is an absolute limit, never to be passed. Forcing it only damages cartilage.
(An extra illustration to make it easier to picture: between the two extremes there is also an intermediate level, 'bone pressing into a mass of soft tissue'. But the core message is still only the two halves above — soft is trainable, bone on bone means stop.)
What this gives you: when a student says 'I'm stuck', ask 'stuck as a stretching pull, or stuck as a hard contact?' — a pull means go on, with control; a hard contact means stop and change the variation.
Try it on the mat now. Sit with the soles of the feet together and let both knees drop naturally to the sides. Then ask yourself:
- Do I feel a pull on the inside of the thigh or the groin (the adductor group lengthening)? → That is a SOFT stop. This is the classic 'soft stop' — it opens up gradually with practice. Be patient and keep releasing.
- Or do I feel a 'contact', a 'jam' deep inside the hip joint, with almost no stretching sensation, the knee simply going no lower? → That is a HARD stop, from the shape of the socket. Pressing further is pointless and harmful.
[REMEMBER] In the same Butterfly, two students may be stopping for two entirely different reasons — and you must handle them differently. The soft-stop student: encourage release and give it time. The hard-stop student: support the knees on a block or a blanket, and never press the knees down.
What this gives you: teach your students to run this test themselves. Once they can tell a stretch from a contact, they protect their own joints — and you need not watch every single person.
A SOFT stop can be moved with stretching. But you CANNOT change a HARD stop.
A map of bone variation: 6 places that make one cue produce different shapes
[REMEMBER] The acetabulum is the 'cup' on the pelvis that holds the head of the femur. It differs from person to person in its depth and in the direction it opens.
- A DEEP socket → the head of the femur is tightly cupped → a very stable joint but with the rotational and opening range blocked early by bone. Such a person finds the Lotus hard and a deep wide seat hard — not through laziness.
- A SHALLOW socket + a favourable orientation → the head of the femur is freer → hip opening and external rotation come easily.
A comparison to remember by: the hip socket is DEEP and stabilised by BONE + thick ligament (so its limits are mostly HARD, inborn and not stretchable). By contrast the shoulder's glenoid is very SHALLOW and stabilised by MUSCLE (so the shoulder's range is softer and more trainable). This is the anatomical reason individual variation at the HIP is markedly greater than at the shoulder.
The shapes most obviously affected: Butterfly, the Lotus, a seated wide-leg position.
What this gives you: when a student 'never opens their hips', the shape of the socket is the likely reason — give them a variation (support the knees) rather than forcing. Don't blame 'tight glutes' for something that is bony structure.
[REMEMBER] The junction between the head and the shaft of the femur has two measurable variants that directly decide the hip's range:
- The neck–shaft angle: shallow at about 115°, normal at about 130°, deep at about 140°. In plain terms: this angle decides at what degree 'the femoral neck meets the rim of the socket' — so in the same direction, one person is hard-blocked earlier than another, and some shapes may be locked out altogether.
- The torsion of the femoral neck (femoral version): the femoral neck twists forwards (anteversion) or backwards (retroversion) relative to the shaft of the bone.
- Someone with anteversion — in plain terms: the legs come together easily and splay out with difficulty: good INTERNAL hip rotation but poor EXTERNAL rotation → the Lotus is hard and hip opening is hard.
- Someone with retroversion — in plain terms: the legs splay out easily and come together with difficulty: the reverse — external rotation easy, internal rotation restricted.
A term easily confused: the 'anteversion / retroversion' of the femoral neck (bony torsion) is NOT the same as 'the PELVIS tipping forward or back'. Don't mix the two.
The shapes affected: the Lotus, the Warriors, and every shape needing external rotation of the thigh.
What this gives you: you don't need the scientific names — just remember 'legs come together easily' or 'legs splay easily'. Understand that and you give the RIGHT variation from the start (don't force a lotus leg on someone who cannot splay), and you can explain convincingly why some people 'never open their hips'.
[GRASP THIS] In many people the tibia (the shin bone) is slightly twisted along its long axis. The consequence: standing with the knee facing straight forward, the foot turns slightly out (or the reverse) — the knee and the toes 'point' in two different directions.
- It sounds like 'a fault to be corrected', but it is in fact a normal variation, and even an advantage for standing balance.
- A dangerous mistake: seeing the leg out of line and trying to 'line the knee and the toes up'. In someone with tibial torsion, forcing that alignment means forcing the twist at the knee joint — a hinge not designed to rotate → damaging the meniscus.
The shapes affected: Mountain, Triangle, and every standing shape.
What this gives you to correct: drop the cue 'the knee always in line with the toes' as a rigid rule for the whole room. Let the foot find its natural angle; judge by whether the knee feels twisted or painful, not by ideal geometry.
[REMEMBER] Each section of the spine moves differently because of 4 structural factors: the shape and size of the vertebrae, the thickness of the discs, how the ribs attach, and the angle and orientation of the facet surfaces. So:
- The neck suits flexion, extension and rotation but not side-bending.
- The chest does not suit rotation (the ribs obstruct it).
- The low back rotates very little (because of the facet orientation).
More importantly: the exact shape of the spinal curves is UNIQUE to each person. A mild scoliosis is very common — it can create the sensation that one leg or one arm is longer than the other, with the convex side of the curve chronically shortened. The size and shape of the coccyx also vary greatly from person to person.
The aim is not 'a back straight as a ruler' but THAT PERSON'S OWN healthy neutral spine — a chain of alternating curves like a spring. With a scoliosis, the aim is to rebalance (lengthening the shortened side), not to force it into a straight mould.
What this gives you: don't panic when a student's back is not 'flat' or their shoulders are not level. Individualise to their own spinal structure; and if you suspect a severe scoliosis, direct them to a specialist.
[REMEMBER] Touching your toes in a forward fold is NOT purely a matter of flexibility. Limb proportions create a structural barrier no amount of stretching erases:
- Long arms + short legs + a long torso → the floor is reached effortlessly.
- Long legs + short arms + a short torso → there is a physical gap between the hands and the floor, however soft the hamstrings become.
On the mechanics of leverage: the longer the lever, the greater the load. In Warrior III, extending both arms forward makes a long lever → a far greater load (from gravity) than holding the hands at the chest. People with different limb proportions take different intensities from the same cue.
What this gives you: you have two 'dose dials' in hand: (1) shorten the lever — let them bend the arms or bring the hands to the chest to reduce the intensity; (2) raise the floor — put the hands on a block or a chair when they do not reach. 'Bring the floor to the person' rather than demanding the person reach the floor.
[GRASP THIS] Not only bone — the number and shape of muscles also differ from person to person. Some people have, and some lack, certain muscles (psoas minor, for instance); many have more — or fewer — muscles or bones than others. Bodies differ to the point where each person expresses a yoga shape in a unique way.
- The diagonal line of the biceps femoris gives the knee and foot a tendency to turn slightly out — a slightly splayed stance is partly a matter of MUSCLE structure, and forcing it straight does not change it.
- The length and tightness of the hamstrings can differ between the two sides → so on the same forward-fold cue, the two sides of the SAME person already produce different shapes — let alone two different people.
What this gives you: it closes the whole of part 3 — variation is not in one place but THROUGHOUT the body, stacked up. Which is why you should never expect two students to produce the same shape.
The hip is where bone variation between people is MARKEDLY GREATER than at the shoulder — and therefore where individual differences in range are largest.
Soft tissue is trainable — but it has a safe ceiling, and ligament is not to be touched
[REMEMBER] We have just seen where BONE blocks the range — the part that cannot be changed. Now to the TRAINABLE side, the soft tissue; but even that has a safe ceiling. 'A trainable soft stop' does NOT mean pulling without limit. Soft tissue has three zones under tension:
- The ELASTIC zone (safe): pull it and the tissue returns to its original length. This is the zone in which we practise to increase the range gradually.
- The YIELD point: past this, the tissue enters the PLASTIC zone — permanently crept, not returning.
- The FAILURE point: a tear.
So the rule: opening a soft stop must be GRADUAL, without charging past the yield point. 'Trainable' always comes with 'within the safe zone'.
What this gives you: when you take a student deeper at a soft stop, go a little at a time, stay for a few breaths, and don't jerk. The technique of engaging the antagonist (contract the front of the thigh for a few breaths, then release) helps open the range safely.
[REMEMBER] Ligament and tendon are all but inelastic — their job is to HOLD the joint stable. Over-stretch them and:
- They do not return to their resting length → the joint is permanently unstable.
- At the hip, for instance: the iliofemoral (Y) ligament limits hip extension and external rotation — that is a HARD barrier, not a place to 'open' further.
The core meaning for Lesson 10: when the range is already blocked by BONE (unchangeable), someone who forces it will unwittingly stretch ligament and tendon — trading stable structure for a few meaningless degrees. That is an injury risk, not progress.
What this gives you: aim the stretching sensation at the MIDDLE of the muscle belly. If a student reports a tight, burning sensation at the joint itself (rather than in the muscle belly), that may be ligament being pulled — have them come back at once.
[GRASP THIS] This is the medical reason to stop, not a scare story. A synovial joint is designed so the two bone ends do NOT touch. When you force past the structural limit:
- The acetabular labrum can become irritated and tear — through misuse, causing groin pain.
- The joint cartilage degenerates, the joint space narrows, the two bone surfaces meet → the body grows bone spurs (osteophytes) → inflammation, pain, and long-term osteoarthritis.
- In an over-arched back, the spinous process of one vertebra can meet the next — 'you cannot force it into a bone-on-bone position'.
What this gives you: when the range is already blocked by structure and you still force it, the result is not 'opening' but cartilage damage. This is the solid biological basis on which you can say with confidence 'stopping here is right; it is not defeat'.
[GRASP THIS] Demolishing the notion that 'the more flexible the better':
- There is a correlation between joint hypermobility ('double-jointedness') and chronic joint pain. A very flexible person should favour STRENGTHENING asanas, building muscle to protect the joint — not stretching further.
- People sit at either end of an inborn ligament spectrum: someone 'born with long enough ligaments' gets into the advanced shapes easily; someone with inelastic ligament 'may practise for years and gain very little freedom' — and forcing them into the mould is wrong.
- Variation from session to session: the hormone relaxin makes women's ligaments looser (in pregnancy, and around ovulation) → so the same person's range differs from day to day. Be careful not to over-stretch at those times.
What this gives you: 'understanding and knowing your own limit matters more than forcing the standard shape'. Read your student's body every session; don't force them on the grounds that 'last time you could do it'.
An over-stretched ligament does NOT necessarily return to its original length — which happens regularly when a student tries to go past their own body's limit.
Four anti-anatomical cues to drop at once
WRONG. Squaring the hips completely is physically impossible for most people, because of pelvic and femoral structure, not through any lack of effort. This is an anti-anatomical cue taught widely, every day.
What this gives you to correct: drop the cue 'force the hips square to the front'. Replace it with 'turn the hips towards the front within what is comfortable, keeping the front knee from collapsing inwards'. Don't force the hip bones forward.
WRONG, AND DANGEROUS. The Lotus demands a large amount of external rotation at the HIP. With a deep socket or a short femoral neck, the hip joint meets bone before there is enough rotation. Forced at that point, the practitioner unconsciously 'borrows' range from the KNEE JOINT — a hinge that barely rotates → the force lands in the wrong place, and the meniscus of the knee tears.
A concrete body-reading measure: a student whose knees are HIGHER THAN the iliac crest in a simple cross-legged seat (Sukhasana) should treat the Lotus as a DANGEROUS shape — they should not try to get into it.
What this gives you: an iron rule: when the hip is blocked (by bone), NEVER borrow range from the knee or the low back. You must get enough external rotation from the ball-and-socket hip first; if there is not enough, give a variation or a prop.
WRONG. Depth is largely a matter of inborn bony structure (a shallow or deep socket, a long or short femoral neck), and does not reflect effort or level. X-rays and observation of real bone shapes show that the difference in range between a 'not very flexible' person and a 'super-flexible' one lies mainly in the SHAPE of the hip socket and the angle of the femoral neck — in bony structure, not in how hard they work.
What this gives you: don't praise 'going deep' as the measure of progress — it unwittingly encourages over-forcing. Praise the right things: body awareness, keeping a healthy spine, breathing evenly, stopping at the right moment.
WRONG (and harmful to both sides). Very often it is simply a normal anatomical limit — nobody's fault at all. Forcing a body to chase a shape its bones do not allow violates the principle of ahimsa (doing no harm) — the ethical foundation of yoga.
What this gives you: it lifts the pressure off you: when there are twelve different shapes, you have not failed. And it lifts the pressure off your student: 'your shape differs from the person beside you because your bones differ, not because you are worse.' Props and variations are the DEFAULT for everyone, not 'a consolation prize for the weak'.
The job is not to stuff your body into the shape, but to let the shape come and meet your body.
What this means for a teacher: read each body, give variations + props, cue openly
[REMEMBER] A three-step frame for individualising without abandoning anybody:
- 1. OBSERVE the proportions & the base shape: look at the arm–leg–torso ratio; have them sit in Sukhasana and see whether the knees are above or below the iliac crest (the no-Lotus test); look at the natural direction of the toes when standing (tibial torsion).
- 2. TEST hip rotation in both directions: internal versus external — whichever is blocked earlier tells you the femoral version, so you can give the right variation.
- 3. ASK about the sensation: 'Do you feel a PULL or a CONTACT?' — a pull (on the opposite side) = muscle, so go on; a contact or jam (in the direction of travel) = bone, so stop and add a prop.
What this gives you: these three questions and observations take a few seconds per student, enough to sort them quickly and decide on a variation — usable even in a class of twenty.
[REMEMBER] Reverse the thinking: props are not 'crutches for the weak' but the tools by which each bony structure can achieve the FUNCTION of the shape. The basic menu:
- A block or chair under the hands — when the hands do not reach the floor (forward folds, Triangle, Half Moon). 'Bring the floor to the person.'
- A block or blanket under the hips — in a seated forward fold, to tip the pelvis forward, drop the weight squarely onto the sitting bones and straighten the spine (especially where tight hamstrings or a tight low back make the pelvis tip back by itself).
- Support under both knees — in Butterfly or a cross-legged seat when the knees cannot come down (a hard stop at the socket).
- A strap around the ball of the foot — joining the hand to the foot when the reach is short.
- A wall — for a sense of alignment; a chair — for anyone with restricted movement.
What this gives you: have props ready for THE WHOLE ROOM and invite everyone to use them as an ordinary option — erasing the stigma that 'needing a block means you are worse'.
[REMEMBER] Because an identical outward form is impossible, cue by SENSATION IN THE TARGET AREA, not by angle or shape. Some cue swaps:
- ❌ 'Bring the knees to the floor' → ✅ 'Release the hips and let the knees fall as far as feels like just enough stretch on the inner thigh.'
- ❌ 'Fold your belly onto your thighs' → ✅ 'Fold from the hip joint until you feel a stretch down the back of the legs, keeping the back long.'
- ❌ 'Square the hips to the front' → ✅ 'Turn the navel towards the front within what is comfortable.'
- ❌ 'Knee in line with the toes' → ✅ 'Put the foot at the angle where the knee feels no painful twist.'
A note: some cues work for one person and are useless for another — experiment and trust your own judgement. The visible shape is only 'a nice photograph'; what decides right from wrong is feeling it in the right place.
What this gives you: open cues free a whole room from one mould, and are automatically safer because they put bodily sensation above outward form.
[REMEMBER] Teach your students (and watch for yourself) the 'come out of the shape immediately' signals:
- Numbness, sharp pain, pain running down a limb → possible nerve compression → release and come out of the shape at once.
- Tingling, cold, a limb feeling 'dead' or dull and lifeless → possible vascular compression → stop at once.
- SHARP pain right INSIDE the joint (quite unlike a strong stretch in the muscle belly) → a bony limit reached, or force landing in the wrong place → stop.
- Having to hold the breath or grimace to maintain the shape → you have gone too far.
This is the bridge between 'objective anatomy' (bones differ) and 'subjective practice' (each person feels and stops for themselves). Thanks to the proprioceptive signals from the deep spinal muscles (multifidus), each student can read their OWN limit — instead of imitating a shape in a photograph.
What this gives you: repeat the 'no forcing' rule in every risky shape. A gentler variation (resting the back of the hand instead of forcing the foot behind the calf in Eagle) is still a LEGITIMATE shape, not 'an inferior version'.
Each person may need a slightly different adjustment according to their own bone and soft-tissue structure — try different techniques and trust your judgement.
Three things to take away from Lesson 10
- 1. Bone shapes the final form. There is no 'one correct shape for everybody' because there is no 'one common skeleton'. 12 students = 12 shapes, and that is normal, not a fault.
- 2. Tell HARD from SOFT. A pull on the opposite side = MUSCLE (trainable; go on with control). A contact or jam in the direction of travel = BONE (stop; change the variation or add a prop). This is the most important professional tool there is.
- 3. Let the shape come to the body. Read each student, give props and variations as the default, and cue by sensation rather than by the magazine shape. Stop forcing — because forcing past a bony limit is an injury, not progress.
Homework: in your next session, pick three students in the SAME asana (Butterfly or a seated forward fold, say). Write down: what different shape each produced, which bone variation you suspect is behind it, and what variation or prop you gave each of them.
So you now know: bone shapes the form, and you must read each body rather than force one mould. But one big question is still hanging — once you know where a student is blocked, which PROP and which VARIATION do you use for each core shape, systematically?
In the next lesson we open the 'variation toolbox': for each foundational asana — the forward fold, the Warriors, Triangle, the wide seat — a menu of variations by structural type, with exactly how to place the props, to the centimetre. From 'understanding why they differ' to 'knowing precisely what to give'. See you in Lesson 11.
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 bodyYou are here
- 11Reading the body as a system of forces (putting it together)Available
A student is folding forward and reports 'a strong pull down the back of the thigh'. Which kind of limit is this, and how do you handle it?