This chapter provides information on Gait Terminology along with the "normal" movement of various lower limb joints and body segments during a gait cycle
The gait cycle is divided into 2 phases, i.e. the Stance phase and the Swing phase. The Stance phase is the period during which the foot remains in contact with the ground. The Swing phase is the period during which the foot is swinging forward (in the air). These 2 phases are further divided into 4 intervals, i.e. Initial Double Support, Single Support, Terminal Double Support and Swing. Traditionally, a gait cycle has been divided into 8 phases, as described by Dr. Jacqueline Perry. However, these 8 phases are difficult to identify during observational analysis. Hence, we have divided the gait cycle into 4 intervals that are based on lower limb movements which can be easily identified during observation.
This interval begins when the ipsilateral foot contacts the ground, either with the heel or the forefoot. During this interval, both feet are in contact with the ground and the body weight is support by both lower limbs. This interval ends with the contralateral foot is lifted off the ground
This interval begins when the contralateral foot is lifted off the ground. During this interval, only the ipsilateral foot is in contact with the ground and the body weight is supported by a single limb as the contralateral limb swings forward. This interval ends when the contralateral foot contacts the ground.
This interval begins when the contralateral foot contacts the ground, either with the heel or the forefoot. During this interval, both feet are in contact with the ground, the body weight is support by both lower limbs and the ipsilateral limb is getting ready to swing forward. This interval ends when the ipsilateral foot is lifted off the ground.
This interval begins when the ipsilateral foot is lifted off the ground in order to swing forward. During this interval, body weight is supported only by the contralateral limb as the ipsilateral limb swings forward. This interval ends when the ipsilateral foot contacts the ground again. Ground contact of the ipsilateral limb completes one gait cycle and begins a new cycle with the 4 intervals.
Foot Rockers
During the Stance phase of gait, the foot remains fixed on the ground and the rest of the body moves forward with respect to the foot. The foot undergoes specific movements, known as the “Foot Rockers” which assist in the forward progression of the body. There are 3 foot rockers which are observed during the IDS, SS and TDS intervals of the gait cycle.
The Heel rocker begins when the heel contacts the ground and ends when the foot is flat on the ground, i.e. both the heel and forefoot are in contact with the ground. During this rocker, the heel acts as the fulcrum and the foot moves about the heel. This rocker assists progression by maintaining the forward momentum of the body and ensuring that the forward velocity is not reduced after ground contact. The Heel rocker is observed during the first half of the IDS interval.
The Ankle rocker begins with a flat foot and ends when the heel is lifted off the ground. During this rocker, the ankle acts as the fulcrum and the tibia rotates forward. The movement of the tibia during this rocker, i.e. from a backward leaning position to a forward leaning position, progresses the body forward during the single support interval. The Ankle rocker is observed during the second half of the IDS interval and the first half of the SS Interval
This rocker begins when the heel is lifted off the ground and ends with ipsilateral toe-off. During this rocker, the forefoot acts as the fulcrum and the tibia continues to rotate forward. This rocker generates forward momentum for the body by creating a “push-off” with the ipsilateral limb. The Forefoot and Toe rocker is observed during the second half of SS interval and the TDS interval.
NOTE: Some books have listed the Forefoot and Toe rockers as 2 different rockers, while others have combined these rockers as a single rocker.
Ankle Movement - Sagittal Plane
In the sagittal plane, the sequence of ankle movement during normal gait is: Plantarflexion, Dorsiflexion, Plantarflexion and Dorsiflexion. The total range of motion at the ankle is about 35°, i.e. approximately 15° of dorsiflexion and 20° of plantarflexion.
Ankle Movement - Coronal Plane
In the coronal plane, the range of motion for inversion and eversion of the ankle is quite small. Due to the small magnitude of movement, ankle motion in the coronal plane is difficult to observe. In pathological gait, if joint motion is exaggerated, coronal plane movement of the ankle is easier to observe.
Knee - Sagittal Plane
The sagittal plane movement of the knee joint in sequential order is: Flexion, Extension, Flexion and Extension. It is important to note that while the knee extends (from a flexed position) during a gait cycle, it never goes into hyperextension. The total range of motion at the knee joint is 0-60°.
Knee - Coronal Plane
In the coronal plane, the abduction – adduction range of motion at the knee is quite small. Due to the small magnitude of movement, knee motion in the coronal plane is difficult to observe. In pathological gait, if joint motion is exaggerated, coronal plane movement of the knee is easier to observe.
Hip - Sagittal Plane
The sagittal plane movement of the hip joint in sequential order is: Flexion and Extension. The hip joint moves into extension from a flexed position in the first half of the gait cycle. In the second half of the gait cycle, it moves into flexion. Hip joint movement is best viewed by observing the movement of the thigh. The total range of motion at the hip joint is approximately 20° of flexion to 25° of extension.
Hip - Coronal Plane
In the coronal plane, the abduction – adduction movement at the hip is due to the movement of the pelvis. Since the magnitude of pelvic movement is small, hip motion in the coronal plane is difficult to observe. In pathological gait, if joint motion is exaggerated, coronal plane movement of the hip is easier to observe.
Pelvis - Sagittal Plane
The Pelvis moves in all 3 planes and the maximum movement in each plane is about 5°. In the sagittal plane, the pelvis tilts anteriorly by about 5°and moves back into the neutral position. Since the magnitude of pelvic movement is small anterior pelvic tilt is difficult to observe in normal gait.
Pelvis - Coronal Plane
In the coronal plane, there is a controlled drop in one side of the pelvis of about 5°. Then the side moves into the neutral position. Since the magnitude of pelvic movement is small, pelvic drop is difficult to observe in normal gait.
Trunk - Sagittal Plane
In the sagittal plane, the trunk stays erect throughout the gait cycle. There is no flexion - extension movement at the trunk.
Trunk - Coronal Plane
In the coronal plane, the trunk stays erect throughout the gait cycle. There is no lateral lean (Right or Left lean) at the trunk.
Step Length
Step length is the forward perpendicular distance from the heel of one foot to the heel of the other foot (or from the tip of the toes of one foot to the other foot). Step length can vary based on a person's height, age or walking speed. The average adult step length is 26 inch - 30 inch (66 cm - 76 cm). There is a high degree of symmetry between the Right and Left step lengths. It is best viewed in the sagittal plane
Step Width
Step width is also known as the walking base. It is the lateral perpendicular distance (i.e. side-to-side) distance) from the mid-point of the Right heel to the mid-point of the Left heel. Step width can vary based on age and gender. The average adult step width is 3 inch - 5 inch (8 cm - 13 cm). It is best viewed in the coronal plane, from the back of the person.
Stance Time
Stance time is the amount of time spent on a limb during its stance phase. It is a measure of the total time the foot is on the ground. The average adult stance time is 0.6-0.8 sec. In normal gait, there is a high degree of symmetry between the Right and Left stance times. While stance time cannot be measured through observation, observational analysis can be used to estimate asymmetry in stance time between the limbs.
Toe-Out Angle
During normal gait, as the body progresses in the forward direction, the foot is rotated outwards. The longitudinal axis of the foot (from mid-heel to second toe) points slightly laterally instead of the straight forward direction. The angle between the line of progression and longitudinal axis of the foot is called the toe-out angle. The average adult toe-out angle is 10° - 15°. It is best viewed in the coronal plane, from the front of the person.
Arm swing occurs passively during a gait cycle and does not require active muscular contraction. Arm swing results from the forward-backward movement of the pectoral girdle (i.e. the upper trunk) in the transverse plane. Movement of the pectoral girdle is in opposition to the forward-backward movement of the pelvis (or the pelvic girdle). Since arm swing is associated with pelvic rotation, observing movement of the arms provides insights into the forward-backward rotation of the pelvis
The most important functions performed by the body during gait can be summarized using the BEEPS acronym
The body has to maintain balance in order to move forward. Balance should be maintained during periods of double-limb support and single-limb support.
There is an inherent symmetry between the right and left sides of the body. Joint movement, muscular activity an neurological control are very similar between the two sides of the body.
Movement of the body during gait is very efficient and very little energy is spent during walking
Throughout the gait cycle, the body progresses forward in a smooth manner. Forward progression is maintained throughout the four intervals despite continuous movement of the body segments
Every step taken during the gait cycle involves transfer of body weight between the limbs and heavy loads on the lower limb joints. The body reduces joint loads by absorbing the shock produced due to weight transfer.
In pathological gait, one or more of the body functions are compromised. The goal of rehabilitation should therefore be to restore these body functions to the best of the patient's ability.
The next sections will discuss how pathologies affect movements at various joints and segments during a gait cycle.