{"schemaVersion":1,"id":"en-mechanism-range-of-motion","type":"mechanism","pillar":"body","locale":"en","translationGroupId":"mechanism-range-of-motion","slugPath":"body/what-limits-range-of-motion","title":"What limits range of motion","shortTitle":"Range limits","summary":"Four things can stop a movement: bone, capsule, muscle length and the nervous system's tolerance. They do not respond the same way — and not all of them respond at all.","level":"intermediate","estimatedMinutes":9,"synonyms":["range of motion","flexibility","mobility","stretching","bony block","stiffness"],"blocks":[{"id":"b1","type":"heading","level":2,"text":"Why does a movement stop?","anchor":"why-does-a-movement-stop"},{"id":"b2","type":"paragraph","content":[{"kind":"text","value":"The question sounds simple, and the common answer — \"the muscle is too short\" — is not. Four different things can stop a movement, and they have neither the same origin nor the same consequences."}]},{"id":"b3","type":"callout","tone":"insight","title":"The answer in three sentences","content":[[{"kind":"text","value":"A range is limited by bone, by the capsule and ligaments, by the length of the muscles crossing the joint, or by the nervous system's tolerance to being put under tension."}],[{"kind":"text","value":"The first two do not change with training. The last two can, in proportions and by mechanisms that remain debated."}]]},{"id":"b4","type":"heading","level":2,"text":"First limit: bone","anchor":"first-limit-bone"},{"id":"b5","type":"paragraph","content":[{"kind":"text","value":"Two bony surfaces eventually meet. It is the hardest limit, literally, and the most individual: it depends on the shape of the parts, which varies noticeably between people."}]},{"id":"b6","type":"paragraph","content":[{"kind":"text","value":"The "},{"kind":"link","value":"hip","href":"/en/body/joints/hip","external":false},{"kind":"text","value":" is the clearest example. The orientation of the socket and the angle of the femoral neck shift the point where the femur meets the pelvis. Two people doing the same "},{"kind":"link","value":"squat","href":"/en/movements/squat","external":false},{"kind":"text","value":" therefore reach different depths without either having anything to do with it."}]},{"id":"b7","type":"definition","term":"Bony block","definition":"A movement stopping because two bony surfaces meet. It gives a firm sense of blocking, with no stretch, and does not change.","alsoKnownAs":["bone-on-bone contact"]},{"id":"b8","type":"heading","level":2,"text":"Second limit: capsule and ligaments","anchor":"second-limit-capsule-and-ligaments"},{"id":"b9","type":"paragraph","content":[{"kind":"text","value":"When the tissues wrapping the joint come under tension, the movement stops. The most telling case is the "},{"kind":"link","value":"hip","href":"/en/body/joints/hip","external":false},{"kind":"text","value":" in extension: its three ligaments wind around the neck and tighten, which limits the movement and allows standing without continuous muscular effort."}]},{"id":"b10","type":"paragraph","content":[{"kind":"text","value":"This limit barely changes, and that is just as well: a capsule that lengthened would lose its restraining role."}]},{"id":"b11","type":"heading","level":2,"text":"Third limit: muscle length","anchor":"third-limit-muscle-length"},{"id":"b12","type":"paragraph","content":[{"kind":"text","value":"This is the one people think of first, and it really only concerns muscles that cross two joints. A single-joint muscle is rarely the limiting factor; a two-joint muscle ends up stretched at both ends at once."}]},{"id":"b13","type":"paragraph","content":[{"kind":"text","value":"The "},{"kind":"link","value":"hamstrings","href":"/en/body/muscles/hamstrings","external":false},{"kind":"text","value":" are the classic example: with the hip flexed and the knee straight, they are lengthened at both ends. That is why the same person can touch their feet with knees bent but not with knees straight — with nothing having changed in the muscle."}]},{"id":"b14","type":"evidence","level":"established","statement":"A muscle crossing two joints can limit the range of one when the other is already placed in lengthening.","detail":"This is a basic principle of functional anatomy, used the same way by descriptive anatomy and by kinesiology. It explains how range depends on the position of neighbouring joints, and it can be verified by simply comparing two positions.","referenceIds":["standring2020","neumann2016"]},{"id":"b15","type":"heading","level":2,"text":"Fourth limit: tolerance","anchor":"fourth-limit-tolerance"},{"id":"b16","type":"paragraph","content":[{"kind":"text","value":"One frequent case remains: nothing blocks, nothing is obviously too short, and the movement stops anyway. Being put under tension triggers a sensation that interrupts the movement before any mechanical limit."}]},{"id":"b17","type":"evidence","level":"uncertain","statement":"Part of the range achievable depends on tolerance to being stretched, not only on the mechanical properties of the tissues.","detail":"Reference kinesiology describes this component, and several stretching protocols show gains in range without any measurable change in tissue length. The size of that contribution and how long it lasts vary widely between studies, and no general conclusion follows today.","referenceIds":["neumann2016"]},{"id":"b18","type":"heading","level":2,"text":"Telling them apart, before concluding","anchor":"telling-them-apart-before-concluding"},{"id":"b19","type":"comparison","title":"Four limits, four signatures","columns":["Limit","Sensation","Changeable"],"rows":[{"label":"Bony block","cells":["Firm stop, no stretch","No"]},{"label":"Capsule and ligaments","cells":["Firm resistance at end range","Barely"]},{"label":"Muscle length","cells":["Stretch, depends on the neighbouring joint","Partly"]},{"label":"Tolerance","cells":["Discomfort before any block","Partly"]}]},{"id":"b20","type":"paragraph","content":[{"kind":"text","value":"The simplest test to tell the third from the first: change the position of the neighbouring joint. If the range increases, a two-joint muscle was the limit; if nothing changes, the limit lies elsewhere."}]},{"id":"b21","type":"heading","level":2,"text":"Seeing the structures involved","anchor":"seeing-the-structures-involved"},{"id":"b22","type":"scene3d","sceneId":"articulations","title":"Four joints, layer by layer","intro":"The scene shows the first three limits in one image: the shape of the surfaces, the capsule wrapping them, and the ligaments tightening. The fourth cannot be seen — which is precisely what makes it hard to discuss.","initialStepId":"hanche","accessibility":{"textAlternative":"A three-dimensional model of four joints from the left side of the body, presented one after another on a paper background. The shoulder shows the shoulder blade, collarbone and upper humerus in bone tones, with the joint capsule, the glenoid labrum and the glenohumeral ligaments in olive grey. The hip shows the hip bone and femur, the capsule wrapping the neck, the acetabular labrum and the three ligaments wound around it. The knee shows the femur, tibia, fibula and kneecap, with the two menisci resting on the tibial plateau, the cruciate ligaments at the centre and the collaterals on either side. The lumbar spine, seen from the side, shows the five vertebrae and the sacrum separated by five discs, with the longitudinal ligaments running in front of and behind the vertebral bodies. The joint tissues are highlighted at each step, the bones staying in the background.","structures":[{"label":"Glenoid labrum","description":"A fibrocartilaginous rim fixed around the edge of the glenoid cavity. It deepens the socket and increases the contact area with the head of the humerus, whose diameter far exceeds that of the cavity.","href":"/en/body/joints/shoulder"},{"label":"Ligaments of the hip","description":"Three bands wound around the capsule — iliofemoral, pubofemoral, ischiofemoral. They tighten as the hip extends, which allows standing without continuous muscular effort.","href":"/en/body/joints/hip"},{"label":"Cruciate ligaments","description":"Two ligaments stretched across the centre of the knee, crossing one in front of the other. They limit the tibia sliding under the femur — forwards for the anterior, backwards for the posterior.","href":"/en/body/joints/knee"},{"label":"Intervertebral discs","description":"Five discs separate the lumbar vertebrae and the sacrum. Each pairs a tough fibrous ring with a more deformable core, which spreads load and allows slight movement between two neighbouring vertebrae.","href":"/en/body/joints/lumbar-spine"},{"label":"Ligaments of the elbow","description":"Two collateral ligaments hold the elbow from the sides, and a ring encircles the head of the radius so it can pivot without leaving its place. The elbow thus combines a hinge and a pivot.","href":"/en/body/joints/elbow"},{"label":"Lateral ligaments of the ankle","description":"Three slender bands link the fibula to the talus and the heel bone. They are markedly thinner than their medial counterparts, which is why the ankle is more easily forced inwards.","href":"/en/body/joints/ankle"}],"steps":[{"id":"epaule","title":"The shoulder","body":"The head of the humerus is far wider than the socket that receives it. The glenoid labrum deepens the rim, the capsule wraps the whole, and three glenohumeral ligaments reinforce it in front. That is the price of mobility: little bone to hold, a great deal of soft tissue."},{"id":"hanche","title":"The hip","body":"Unlike the shoulder, the femoral head sits deep in the socket, which the acetabular labrum extends further. The three ligaments wind around the neck and tighten in extension: standing, they carry part of the work the muscles no longer have to supply."},{"id":"genou","title":"The knee","body":"Two poorly matched surfaces — the rounded condyles of the femur on an almost flat tibial plateau. The menisci fill the gap, the cruciates hold the tibia front to back, the collaterals hold it side to side. Remove any one of these parts and the load shifts onto the others."},{"id":"rachis-lombaire","title":"The lumbar spine","body":"Five vertebrae, five discs, and a set of ligaments running the whole height. Each level moves only a few degrees; it is their sum that gives the trunk its range. The longitudinal ligaments limit flexion and extension, the ligamenta flava close the back of the canal."},{"id":"coude","title":"The elbow","body":"The elbow does two things inside one capsule. The humerus and ulna form a hinge that flexes and extends in a single plane; the head of the radius pivots in place inside a ligamentous ring, which turns the palm over. The two collateral ligaments hold it all from the sides."},{"id":"cheville","title":"The ankle","body":"The talus is wedged between the two malleoli like a tenon in a mortise. On the inner side, a thick fan-shaped ligament; on the outer side, three markedly thinner bands. That asymmetry is no detail: it explains which way the ankle most often gives."}],"license":"Z-Anatomy et BodyParts3D — CC-BY-SA 4.0"}},{"id":"b23","type":"heading","level":2,"text":"What this page does not do","anchor":"what-this-page-does-not-do"},{"id":"b24","type":"callout","tone":"limit","title":"No protocol, no duration","content":[[{"kind":"text","value":"Body Lab describes mechanisms, not conduct. This page proposes no exercise, no stretching duration and no protocol: the four limits are not distributed the same way in two people, and nothing here tells you which one dominates in your case."}],[{"kind":"text","value":"Stiffness that settles in, range that shrinks for no apparent reason, or pain on being stretched belong to a health professional."}]]},{"id":"b25","type":"heading","level":2,"text":"Sources","anchor":"sources"},{"id":"b26","type":"sourceList","title":"Main sources","referenceIds":["standring2020","neumann2016"]},{"id":"b27","type":"shapierAction","actionId":"exercise-sliding-hamstring-curl","label":"See an exercise for the hamstrings","description":"See the sliding hamstring curl in Shapier, an exercise that works the hamstrings.","webTarget":"https://shapier.app/en/exercises/sliding-hamstring-curl","appTarget":"shapier://exercises/sliding-hamstring-curl"},{"id":"b28","type":"quiz","title":"Check my understanding","questions":[{"id":"q1","prompt":"Does 'the muscle is too short' explain every stopped movement?","choices":[{"id":"q1c1","label":"No, four distinct limits can stop a movement: bone, capsule and ligaments, muscle length and the nervous system's tolerance.","correct":true,"explanation":"This is the page's central correction: the common answer is too simple."},{"id":"q1c2","label":"Yes, a too-short muscle is the only possible cause.","correct":false,"explanation":"That is the common answer, but bone, capsule or tolerance can also stop the movement."},{"id":"q1c3","label":"No, it is always the capsule that blocks.","correct":false,"explanation":"The capsule is one of the four limits, not the only one, and it barely changes."}]},{"id":"q2","prompt":"Which limits can training change?","choices":[{"id":"q2c1","label":"Muscle length and tolerance, and only partly.","correct":true,"explanation":"Bone and capsule do not change with training; the last two can, in proportions that remain debated."},{"id":"q2c2","label":"All four, with enough work.","correct":false,"explanation":"A bony block does not change, and a capsule that lengthened would lose its restraining role."},{"id":"q2c3","label":"None, range of motion is fixed.","correct":false,"explanation":"Muscle length and tolerance can change, even if the size and durability of those gains remain debated."}]},{"id":"q3","prompt":"Why can the same person touch their feet with knees bent but not with knees straight?","choices":[{"id":"q3c1","label":"Because the hamstrings cross two joints: with the hip flexed and the knee straight, they are lengthened at both ends at once.","correct":true,"explanation":"The position of the neighbouring joint changes the range without anything having changed in the muscle."},{"id":"q3c2","label":"Because the muscle gets shorter when the knee straightens.","correct":false,"explanation":"Nothing changes in the muscle: being stretched at both ends is what limits the movement."},{"id":"q3c3","label":"Because bone ends up blocking when the knee is straight.","correct":false,"explanation":"A bony block would give the same firm stop whatever the knee position; here, moving the knee changes the range, the sign of a limiting two-joint muscle."}]}]},{"id":"b29","type":"relatedContent","title":"Read next","targetIds":["en-anatomy-hip-joint","en-anatomy-ankle-joint","en-anatomy-hamstrings"]}],"relations":[{"type":"prerequisite","targetId":"en-anatomy-hip-joint"},{"type":"explains","targetId":"en-anatomy-ankle-joint"},{"type":"uses-structure","targetId":"en-anatomy-shoulder-joint"},{"type":"next-step","targetId":"en-movement-squat"}],"authors":["equipe-editoriale-shapier"],"reviewers":["Thanh Chau"],"references":[{"id":"standring2020","authors":"Standring S","year":2020,"title":"Gray's Anatomy: The Anatomical Basis of Clinical Practice, 42nd edition","source":"Elsevier","kind":"book","url":"https://shop.elsevier.com/books/grays-anatomy/standring/978-0-7020-7705-0"},{"id":"neumann2016","authors":"Neumann DA","year":2016,"title":"Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation, 3rd edition","source":"Elsevier","kind":"book","url":"https://shop.elsevier.com/books/kinesiology-of-the-musculoskeletal-system/neumann/978-0-323-28753-1"}],"review":{"publishedAt":"2026-08-02","reviewedAt":"2026-08-02","reviewDueAt":"2027-08-02","evidenceLevel":"probable"},"limitations":["The relative share of the four limits described cannot be measured directly in a person: it is inferred from examination and comparison, not from an image.","The nervous system's contribution to perceived range remains debated, and the protocols that demonstrate it vary widely in their conclusions.","This page proposes no exercise, no stretching duration and no protocol: that would be personalised advice.","Stiffness that settles in, range that shrinks for no reason, or pain on stretch belong to a health professional."],"seo":{"title":"What limits range of motion — bone, capsule, muscle and tolerance","description":"Four possible limits to a movement, how to tell them apart, and why one instruction produces different positions in different people.","canonicalPath":"/en/body/what-limits-range-of-motion","image":"/og/en/mechanism-range-of-motion.png"},"app":{"offlineEligible":true},"version":1}