The Gait Cycle

Original Editor - Karsten De Koster Top Contributors - Daphne Xuan and Tarina van der Stockt

The Gait Cycle

The action of walking may be summarised by the following sequence:

1. Registration and activation of the gait command within the central nervous system.
2. Transmission of gait signals to the peripheral nervous system.
4. Contraction of muscles.
5. Generation of forces across joints
6. Regulation of joint forces and moments by skeletal segments.
7. Generation of ground reaction forces.

Normal gait consists of two phases: stance phase; swing phase. These phases are further divided into a total of 8 events. The gait cycle involves a combination of open and closed chain activities.

Stance Phase

The stance phase occupies 60% of the total gait cycle, during which some part of the foot is in contact with the ground. It is further divided into five events:

1. Initial contact/heel strike
2. Loading response/foot flat
3. Mid-stance
4. Terminal stance/heel off
5. Pre-swing/toe off

Swing Phase

The swing phase occupies 40% of the total gait cycle , during which the foot is not in contact with the ground and the bodyweight is borne by the other leg and foot. It is further divided into 3 events:

1. Initial swing
2. Mid-swing
3. Late swing

In a complete two-step cycle both feet are in contact with the ground at the same time for about 25 per cent of the time. This part of the cycle is called the double-support phase. The rest of the time is spent in single-support, when only one foot is in contact with the ground.

The 90-second video below gives the basics of this cycle:

Breakdown of Gait Cycle Events

Heel Strike (or initial contact) - Short period, begins the moment the foot touches the ground and is the first phase of double support.

Involves:

• 30° flexion of the hip: full extension in the knee: ankle moves from dorsiflexion to a neutral (supinated 5°) position then into plantar flexion.
• After this, knee flexion (5°) begins and increases, just as the plantar flexion of the heel increased.
• Plantar flexion is allowed by eccentric contraction of the tibialis anterior
• Extension of the knee is caused by a contraction of the quadriceps
• Flexion is caused by a contraction of the hamstrings,
• Flexion of the hip is caused by the contraction of the rectus femoris.

Foot Flat (or loading response phase)

• Body absorbs the impact of the foot by rolling in pronation.
• Hip moves slowly into extension, caused by a contraction of the adductor magnus and gluteus maximus muscles.
• Knee flexes to 15° to 20° of flexion.
• Ankle plantarflexion increases to 10-15°.

Midstance

• Hip moves from 10° of flexion to extension by contraction of the gluteus medius muscle.
• Knee reaches maximal flexion and then begins to extend.
• Ankle becomes supinated and dorsiflexed (5°), which is caused by some contraction of the triceps surae muscles.
• During this phase, the body is supported by one single leg.
• At this moment the body begins to move from force absorption at impact to force propulsion forward.

Heel Off

• Begins when the heel leaves the floor.
• Bodyweight is divided over the metatarsal heads.
• 10-13° of hip hyperextension, which then goes into flexion.
• Knee becomes flexed (0-5°)
• Ankle supinates and plantar flexes.

Toe Off/pre-swing

• Hip becomes less extended.
• Knee is flexed 35-40°
• Plantar flexion of the ankle increases to 20°.
• The toes leave the ground.

Early Swing

• Hip extends to 10° and then flexes due to contraction of the iliopsoas muscle 20° with lateral rotation.
• Knee flexes to 40-60°
• Ankle goes from 20° of plantar flexion to dorsiflexion, to end in a neutral position.

Mid Swing

• Hip flexes to 30° (by contraction of the adductors) and the ankle becomes dorsiflexed due to a contraction of the tibialis anterior muscle.
• Knee flexes 60° but then extends approximately 30° due to the contraction of the sartorius muscle.(caused by the quadriceps muscles).

Late Swing/declaration

• Hip flexion of 25-30°
• Locked extension of the knee
• Neutral position of the ankle.