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Movement
Intermediate
8 min read
Kinetic atlas

Running

What separates running from walking is not speed but an instant with no support. That instant changes everything: the forces taken, the role of the tendons and the way energy circulates.
Posterior view
Contact
Current phase

Contact

0 %
The foot touches the ground ahead of or beneath the body, depending on speed and landing style.
Put it into practice in Shapier
Calf raises, which load the calves and the calcaneal tendon, are practised in Shapier; Body Lab only explains why this spring matters in running.
Work the calf spring
Walking and running, two mechanisms
Ground contact
Always at least one foot · Interrupted by a flight phase
Double support
Twice per cycle · None
Vertical ground force
Close to body weight · On the order of double

A difference in kind, not in degree

Running is often described as accelerated walking. Mechanically that is inaccurate: the two movements do not work the same way, and passing from one to the other is a switch, not a progression.
The walking page sets the rule: in a step, at least one foot is always on the ground. Running begins exactly where that rule stops applying.
Flight phase
The instant in the cycle where neither foot touches the ground. It replaces the double support of walking and defines running.
airborne time
Certainty level · Established
Running differs from walking by the disappearance of double support and the appearance of a phase where neither foot touches the ground.
This is the criterion used in locomotion analysis, measured by force plates and motion capture. As speed increases, the duration of ground contact decreases and that of the flight phase increases; the criterion itself, however, does not depend on speed.
Novacheck TF (1998) · Perry J, Burnfield JM (2010)

What the unsupported instant costs

A body no longer held up falls. All the mechanics of running follow from that fall, which must be taken on one leg.
Certainty level · Established
The vertical force exerted on the ground during a running contact is on the order of double that of a walking contact.
The review gathers force plate measurements comparing walking, running and sprinting. The values reported depend markedly on speed, on the surface and on how the foot lands: the order of magnitude is robust, a precise value is not, and it does not transfer to a given runner.
Novacheck TF (1998)
That load is not spread evenly. It is concentrated into a shorter contact, which leaves less time to absorb it and shifts part of the work from the muscles to the passive structures.

A spring, no longer a pendulum

This is the deepest change, and the most interesting.
Walking works as an inverted pendulum: the body rises over the planted foot and trades positional energy for movement energy. That mechanism requires continuous contact with the ground.
Running works differently. At foot strike the body drops and the tendons of the lower limb — the calcaneal tendon first among them — lengthen while storing elastic energy. At push-off they shorten and give it back. The body no longer swings, it bounces.

Walking and running, two mechanisms

Criterion
Walking
Running
Ground contact
Always at least one foot
Interrupted by a flight phase
Double support
Twice per cycle
None
Vertical ground force
Close to body weight
On the order of double
Economy mechanism
Pendulum exchange
Elastic return
Role of the tendon
Transmission
Transmission and storage
That switch gives the tendon a role it does not have in walking. It no longer merely transmits the muscle's force to bone: it deforms and returns what it received. The muscle, for its part, works at times at nearly constant length while the tendon lengthens — a situation the contraction regimes page makes readable.

The phases of a stride

One cycle, from one contact to the next of the same foot

  • 1
    Contact
    0 %
    The foot touches the ground ahead of or beneath the body, depending on speed and landing style.
  • 2
    Absorption
    0–20 %
    Ankle, knee and hip flex; muscles and tendons take the fall.
  • 3
    Propulsion
    20–40 %
    The same structures shorten; the calf and the hip extensors relaunch the body.
  • 4
    Flight phase
    40–70 %
    No foot on the ground. The free leg folds and swings through.
  • 5
    Preparation
    70–100 %
    The hamstrings brake the advancing leg, which readies itself for the next contact.

Who works, and how

The muscles are the same as in walking. What changes is the intensity and the time available.
  • The calves and the calcaneal tendon form the main spring of the lower limb.
  • The hamstrings brake the leg at the end of swing, at speeds far above those of walking.
  • The glutes supply the hip extension that relaunches the body.
  • Gluteus medius holds the pelvis, as in walking but never with the benefit of double support.
  • The quadriceps absorbs at every contact, in the braked regime.

Seeing the posterior chain

Posterior view

The scene shows the back of the body: glutes, hamstrings and calves, the three groups that relaunch the body at every contact. Without the 3D, the picture fits in one sentence: propulsion comes from behind, and the chain producing it runs from hip to heel.
Current step
Posterior view
The back of the body. The trapezius links the neck to the shoulder blades, the latissimus dorsi fans down to the pelvis, the erector spinae flank the spine, and the triceps fills the back of the arm. Glutes, hamstrings and calves form the posterior chain from hip to ankle.
Scene description
A three-dimensional diagram of a standing human body, arms by the sides, built from simplified paper-coloured volumes. Twelve priority muscle groups are laid over this outline in terracotta: at the front, pectoralis major, the deltoid, biceps brachii, the abdominal wall and the quadriceps; at the back, the trapezius, latissimus dorsi, the erector spinae, triceps brachii, the glutes, the hamstrings and the calves. A simplified skeleton — skull, spine, ribcage, pelvis, humerus, femur and tibia — can be shown beneath the outline to reveal the bony levers these muscles pull on. Each group is selectable and opens its own reference page. This is a teaching diagram with stylised volumes, not an exact anatomical reconstruction.
Visible structures
  • Pectoralis major
    A thick sheet running from the clavicle, the sternum and the upper costal cartilages to the lateral lip of the bicipital groove of the humerus. It draws the arm towards the midline and forwards, and drives horizontal pushing.
  • Deltoids
    Three heads — anterior, lateral and posterior — running from the clavicle, the acromion and the spine of the scapula to the deltoid tuberosity of the humerus. Together they raise the arm; separately they carry it forwards, out to the side or backwards.
  • Biceps brachii
    Two heads arising from the scapula — the supraglenoid tubercle and the coracoid process — joining on the radial tuberosity. It flexes the elbow and supinates the forearm, and contributes to every pulling movement.
  • Abdominal wall
    Rectus abdominis, the external and internal obliques and transversus, running from the ribs and sternum to the pubis and iliac crest. They flex and rotate the trunk and, above all, stabilise the spine by regulating intra-abdominal pressure.
  • Quadriceps
    Four heads — rectus femoris, vastus lateralis, vastus medialis and vastus intermedius — joining through the quadriceps tendon onto the patella and then the tibial tuberosity. They extend the knee, and rectus femoris also flexes the hip.
  • Trapezius
    A diamond-shaped muscle spanning from the occiput and the cervical and thoracic spinous processes to the clavicle, the acromion and the spine of the scapula. Its upper, middle and lower portions elevate, retract and depress the scapula.
  • Latissimus dorsi
    A broad fan arising from the lower thoracic vertebrae, the thoracolumbar fascia, the iliac crest and the lowest ribs, converging on the bicipital groove of the humerus. It pulls the arm down and back, and drives vertical pulling.
  • Erector spinae
    Muscular columns — iliocostalis, longissimus and spinalis — running from the sacrum and iliac crest to the ribs, the vertebrae and the skull, on either side of the spinous processes. They extend the spine and control the trunk as it lowers.
  • Triceps brachii
    Three heads — long, lateral and medial — arising from the scapula and the back of the humerus and joining on the olecranon of the ulna. It extends the elbow, and its long head also assists shoulder extension.
  • Glutes
    Gluteus maximus, medius and minimus, arising from the iliac wing and the sacrum and inserting on the femur and the iliotibial tract. They extend, abduct and rotate the hip, and drive the pelvis upright in the hinge and the squat.
  • Hamstrings
    Biceps femoris, semitendinosus and semimembranosus, running from the ischial tuberosity to the tibia and fibula. They extend the hip and flex the knee, and control the trunk as it lowers in the hip hinge.
  • Calves
    The gastrocnemius and soleus, joining through the Achilles tendon onto the calcaneus. They plantarflex the ankle, and the gastrocnemius, which crosses the knee, also assists knee flexion.
  • Rotator cuff
    Four short muscles running from the shoulder blade to the top of the humerus. Their tendons merge into a sheet that holds the head of the bone against its socket while the deltoid moves the arm.
  • Serratus anterior
    A sheet hooked onto the upper ribs by triangular slips, passing under the shoulder blade and attaching to its inner border. It holds the blade against the ribcage and rotates it.
  • Iliopsoas
    The only muscle linking the lumbar spine directly to the femur. It descends from the vertebrae and the iliac fossa, curves around the rim of the pelvis and attaches to the lesser trochanter.
  • Hip adductors
    Five muscles running from the pubis to the back of the femur in overlapping layers. They draw the thigh towards the midline and control the pelvis in single-leg stance.
  • Forearm muscles
    Masses gathered near the elbow, continued by long tendons to the wrist and fingers. They drive the hand from a distance and carry grip strength.
  • Tibialis anterior
    A muscle pressed against the outer surface of the tibia, its tendon swinging towards the inside of the foot. It lifts the toes on every step and brakes the forefoot after heel strike.
  • Diaphragm
    A muscular dome running from the lower border of the ribs, the sternum and the lumbar vertebrae to a central tendon. As it contracts it descends, the chest gains volume and air enters: it is the engine of quiet breathing, and the ceiling of the abdominal cavity.
Guided steps
  • 1/5
    The front of the body. Pectoralis major covers the upper chest, the deltoid caps the shoulder, the biceps fills the front of the arm, the abdominal wall links the ribs to the pelvis, and the quadriceps fills the front of the thigh. Further out on the limbs, the forearm muscles drive the wrist and hand, and tibialis anterior lifts the foot.
  • 2/5
    The back of the body. The trapezius links the neck to the shoulder blades, the latissimus dorsi fans down to the pelvis, the erector spinae flank the spine, and the triceps fills the back of the arm. Glutes, hamstrings and calves form the posterior chain from hip to ankle.
  • 3/5
    Beneath the visible groups work muscles no silhouette shows. The rotator cuff holds the head of the humerus against the shoulder blade, serratus anterior keeps the shoulder blade flat on the ribcage, the iliopsoas links the lumbar spine to the femur, and the adductors fill the inner thigh. Deeper still, the diaphragm closes the trunk as a dome, inside the ribs. They orient and stabilise more than they move.
  • 4/5
    In a push, force starts at the ground, travels through the quadriceps and the abdominal wall, and then pectoralis major, the anterior deltoid and the triceps drive the load away from the trunk. The skeleton acts as the lever: no group works alone, and the quality of the movement comes from their sequencing.
  • 5/5
    In a pull, the latissimus dorsi and trapezius bring the arm and shoulder blade towards the trunk while the biceps flexes the elbow. Glutes, hamstrings and erector spinae hold the pelvis and spine so that force transfers without the trunk collapsing.
Model licence · Z-Anatomy et BodyParts3D — CC-BY-SA 4.0

What this page does not establish

Caution
A subject where consensus is missing
How the foot lands, the choice of shoe, cadence, "correct" running form and their relationship with injury are the subject of numerous studies and diverging conclusions. Body Lab does not settle these and recommends nothing on them: describing a mechanism does not allow a practice to be deduced from it.
What is described here is what movement analysis measures: the presence of a flight phase, the order of magnitude of the forces, the elastic role of the tendons. The rest goes beyond what the literature cited supports.
Pain appearing or returning while running belongs to a health professional, who has the context a page does not.

What the model does not show

Limit
A scene cannot run
As for walking, the anatomical scenes are fixed meshes with no animation skeleton. They locate the structures involved; they play no stride, and the sequence in time is carried by the text.
Running presupposes walking, whose cycle it takes up while removing double support, and shares with the lunge the constraint of single-leg stance. On the structural side it calls on the calves, the hamstrings, the glutes, the quadriceps and the tendon, whose elastic role becomes decisive here.

Sources

Main sources

  • Novacheck TF (1998). The biomechanics of running. Gait & Posture.
  • Perry J, Burnfield JM (2010). Gait Analysis: Normal and Pathological Function, 2nd edition. SLACK Incorporated.
  • Neumann DA (2016). Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation, 3rd edition. Elsevier.
Put it into practice in Shapier

Work the calf spring

Calf raises, which load the calves and the calcaneal tendon, are practised in Shapier; Body Lab only explains why this spring matters in running.
Work the calf spring
Body Lab explains; Shapier lets you act and track.

Check my understanding

What mechanically distinguishes running from walking?
Which mechanism allows running to save energy?
What does this page say about the link between running technique, footwear and injury?
Choose an answer

Read next

  • Walking
    The most frequent movement of the human body, and the least described. One step involves some twenty muscles whose main work is braking, and a balance problem nothing signals.
    With a 3D scene
  • The tendon
    The part that links a muscle to a bone. It transmits force, briefly stores it like a spring, and adapts far more slowly than the muscle it continues.
    With a 3D scene
  • The aerobic system
    The pathway that supplies most of the energy as soon as an effort lasts. It burns carbohydrate and fat with oxygen, produces a great deal but slowly, and never switches off.
    With a 3D scene

Available offline

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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
  • Ground force values vary with speed, surface, footwear and how the foot lands: the orders of magnitude given here do not hold for any particular runner.
  • Body Lab's scenes are fixed meshes with no animation skeleton: none of them can show a stride.
  • The link between running technique, foot strike pattern, footwear and injury is a debated subject with no consensus. This page describes a mechanism and draws no recommendation from it.
  • Pain appearing or returning while running belongs to a health professional: this page allows no individual assessment.
Sources
  • Novacheck TF (1998). The biomechanics of running. Gait & Posture.
  • Perry J, Burnfield JM (2010). Gait Analysis: Normal and Pathological Function, 2nd edition. SLACK Incorporated.
  • 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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