When we walk, we make the use of our two legs, alternately, to provide both support and propulsion, with at least one foot being in contact with the ground at all times. An individual’s style or way of walking – may change slightly with mood.
While the terms gait and walking are often used interchangeably, the word gait refers to the manner or of walking, rather than the actual walking process.
The gait cycle is the time interval between the exact same repetitive events of walking that generally begin when one foot contacts the ground [though ideally gait cycle can be considered from any position of the foot during walking].
To elaborate, if we consider beginning from right foot contacting the ground, it would be followed by lifting left foot off and thursting it forward where it touches the ground. As the left foot is touching the ground, right foot is getting off the ground and is thrust forward and contacts the ground again.
The time when right foot contact the ground to the time when it contacts again constitutes one gait cycle.
It refers to all activity that occurs between two successive heel contacts of the same foot. As noted before, it is broken up into stance phase and swing phase.
Stance Phase of Gait Cycle
Stance phase is part of gait cycle that occurs when the foot is in contact with the ground. It begins with heel strike and ends with toe off of same foot. Stance phase accounts for accounts for 60% of the gait cycle.
Stance has Several phases
- Heel strike
- Foot flat
- Heel off
- Toe off
It starts when the heel comes in contact with floor. The ankle is in neutral position, knee is slightly flexed and hip is approximately in 30 degrees of flexion.
With heel strike body weight begins to shift onto stance limb.
In this, the entire foot is in contact with floor. The ankle moves into approx. 5-10 degrees of plantar flexion and knee moves into 15 degrees of flexion. the hip moves into extension allowings trunk and body to catch up to the limb. The weight of the body continues to shift on the stance limb.
It is the point at which body passes over the stance limb and where the leg is approaching the vertical position offering single-limb support with other limb freely swinging forward.
The ankle moves into slight dorsiflexion, knee extends and hip continues to extend. Trunk is in neutral position of rotation and arms are parallel to body.
Heel off occurs when when heel just begins to lift off floor. Ankle is in dorsiflexion initially and then in plantar flexion. Knee is extended and prepares to flex, hip is in hyperextension and trunk rotates to same side.
It is time in gait cycle when toes just leave the floor to when the toes leave the floor. Simultaneously, the opposite foot is in foot flat phase. It is end of stance phase and beginning of swing phase. Toes go into hyperextension and ankle begins to plantar flex and knee keeps moving to flexion. By end of this phase, the hip starts flexing.
Swing Phase of Gait Cycle
It is part of gait cycle when the foot is not in contact with the ground. It begins when the foot leaves the floor and ends with heel strike of the same foot and accounts for accounts for 40% of the gait cycle. It is non weight bearing phase of gait. and consists of following phases.
In acceleration phase, the limb is behind body and moving to catch up, ankle moves into into dorsiflexion. Both knees and hip continue to flex.
This phase involves shortening of limb to clear ground. The ankle is in neutral position and knee in maximum flesion. Hip continues to flex.
Deceleration is last of swing phase. In this, ankle is maintained in neutral, preparing for heel strike and knee moves to almost full extension while hip is in flexion.
Double Support and Single Support
Double support is the period in gait cycle when both feet are in contact with the floor. It occurs when one one limb is ending stance phase and the opposite limb begins stance phase. About 10 percent of gait cycle is spent in double support and it changes with speed. Faster gait leads to less double support time and slower gait leads to more time in double support.
Single Support is period when only one foot is in contact with the ground. There are two periods of single support, right stance and left stance and
In running there is a period when none of the foot is on the ground. It is called non support and this differentiates running from waling as non support does not occur in walking.
Stride Length, Step and Cadence
Stride length is the distance traveled in one stride i.e. between two consecutive heel strike of the same foot. Step is the period covered between heel strike of one foot to heel strike of opposite foot.
Step length is the distance covered between heel strike of one limb and heel strike of the other limb.
Step Width is the distance by which feet are apart during walking.. For measurement purpose the distance between the heel centers of two consecutive foot contacts is taken as step width. Normally it is 2 – 4 inches
Cadence is number of steps taken per minute and varies with walking speed.
Here is a video on gait cycle.
Other Associates Movements
Center of gravity is highest at mid-stance, lowest at heel strike and the movement in normal course is about 2 inches.
Horizontal Displacement of center of gravity is side to side shift and is maximum at time of single support phase of mid-stance. It is also about 2-4 inches.
Lateral pelvic tilt occurs when the weight is taken off the limb at toe off. In this hip abductors on contra-lateral side work to keep pelvis level.
Arms swing occurs in opposition of trunk rotation to control the amount of trunk rotation by providing counter-rotation
Normal Gait Variations
A child walks with wider base, faster cadence and shorter stride length. Initial contact with floor is with flat foot and knees remain mostly extended during stance phase.
Elderly walk slower, spend more time in stance phase. There are longer periods of double support, shorter steps, less vertical displacement and greater horizontal displacement.
Foot Pronation Pattern
Neutral pronation is the normal amount of pronation when the weight distributes fairly evenly among all of the toes with a slight emphasis on the big toe and second toe.
This pattern causes the push off almost completely from the big toe and second toe. Tibia vara of 10 degrees, forefoot varus, leg length discrepancy, ligamentous laxity, or tight or weak gastrocnemius and soleus muscles have been associated with overpronation of foot.
The weight of the body isn’t transferred at all to the big toe, forcing the outside of the foot to bear load.
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