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Mechanism
Intermediate
9 min read

What limits range of motion

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.
3D scene
Four joints, layer by layer
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.
Open in the explorer

Why does a movement stop?

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.
Key point
The answer in three sentences
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.
The first two do not change with training. The last two can, in proportions and by mechanisms that remain debated.

First limit: bone

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.
The hip 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 squat therefore reach different depths without either having anything to do with it.
Bony block
A movement stopping because two bony surfaces meet. It gives a firm sense of blocking, with no stretch, and does not change.
bone-on-bone contact

Second limit: capsule and ligaments

When the tissues wrapping the joint come under tension, the movement stops. The most telling case is the hip in extension: its three ligaments wind around the neck and tighten, which limits the movement and allows standing without continuous muscular effort.
This limit barely changes, and that is just as well: a capsule that lengthened would lose its restraining role.

Third limit: muscle length

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.
The hamstrings 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.
Certainty level · Established
A muscle crossing two joints can limit the range of one when the other is already placed in lengthening.
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.
Standring S (2020) · Neumann DA (2016)

Fourth limit: tolerance

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.
Certainty level · Uncertain
Part of the range achievable depends on tolerance to being stretched, not only on the mechanical properties of the tissues.
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.
Neumann DA (2016)

Telling them apart, before concluding

Four limits, four signatures

Limit
Sensation
Changeable
Bony block
Firm stop, no stretch
No
Capsule and ligaments
Firm resistance at end range
Barely
Muscle length
Stretch, depends on the neighbouring joint
Partly
Tolerance
Discomfort before any block
Partly
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.

Seeing the structures involved

Four joints, layer by layer

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.
Current step
The hip
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.
Scene description
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.
Visible structures
  • Glenoid labrum
    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.
  • Ligaments of the hip
    Three bands wound around the capsule — iliofemoral, pubofemoral, ischiofemoral. They tighten as the hip extends, which allows standing without continuous muscular effort.
  • Cruciate ligaments
    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.
  • Intervertebral discs
    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.
  • Ligaments of the elbow
    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.
  • Lateral ligaments of the ankle
    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.
Guided steps
  • 1/6
    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.
  • 2/6
    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.
  • 3/6
    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.
  • 4/6
    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.
  • 5/6
    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.
  • 6/6
    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.
Model licence · Z-Anatomy et BodyParts3D — CC-BY-SA 4.0

What this page does not do

Limit
No protocol, no duration
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.
Stiffness that settles in, range that shrinks for no apparent reason, or pain on being stretched belong to a health professional.

Sources

Main sources

  • Standring S (2020). Gray's Anatomy: The Anatomical Basis of Clinical Practice, 42nd edition. Elsevier.
  • Neumann DA (2016). Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation, 3rd edition. Elsevier.
Put it into practice in Shapier

See an exercise for the hamstrings

See the sliding hamstring curl in Shapier, an exercise that works the hamstrings.
See an exercise for the hamstrings
Body Lab explains; Shapier lets you act and track.

Check my understanding

Does 'the muscle is too short' explain every stopped movement?
Which limits can training change?
Why can the same person touch their feet with knees bent but not with knees straight?
Choose an answer

Read next

  • The hip
    A sphere set deep in a socket, locked by three ligaments that tighten in extension. That is what makes standing possible without continuous muscular effort.
    With a 3D scene
  • The ankle
    The talus is wedged between two malleoli like a tenon in a mortise. The ligaments holding it are not symmetrical, and that asymmetry explains a great deal.
    With a 3D scene
  • Hamstrings
    The hamstrings occupy the back of the thigh. They extend the hip and flex the knee, and their length depends on the combined position of these two joints.
    With a 3D scene

Where to go next

Available offline

Offline download is available in the mobile app.

Trust and method

Author
equipe-editoriale-shapier
Editorial review
Thanh Chau
Scientific review
Pending
Published on
August 2, 2026
Reviewed on August 2, 2026
Next review due August 2, 2027
Limits of this page
  • 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.
Sources
  • Standring S (2020). Gray's Anatomy: The Anatomical Basis of Clinical Practice, 42nd edition. Elsevier.
  • Neumann DA (2016). Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation, 3rd edition. Elsevier.
Educational content. Body Lab does not diagnose and does not replace professional advice.
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