Bipedal gait cycle
A (bipedal) gait cycle is the time period or sequence of events or movements during locomotion in which one foot contacts the ground to when that same foot again contacts the ground, and involves propulsion of the centre of gravity in the direction of motion. A single gait cycle is also known as a stride.
Each gait cycle or stride has two phases:
- Stance Phase, the phase during which the foot remains in contact with the ground, and the
- Swing Phase, the phase during which the foot is not in contact with the ground.
Components of gait cycle
Phases
Stance Phase: The stance phase is that part of a gait cycle during which the foot remains in contact with the ground. For analyzing gait cycle one foot is taken as reference and the movements of the reference foot are studied. It constitutes 60 percent of the gait cycle. In stance phase the reference foot undergoes five movements:
- Initial Contact (Heel Strike): In initial contact, the heel is the first bone of the reference foot to touch the ground.
- Loading Response (Foot Flat): In loading response phase, the weight is transferred onto the referenced leg. It is important for weight-bearing, shock-absorption and forward progression.
- Mid Stance: It involves alignment and balancing of body weight on the reference foot.
- Terminal Stance: In this phase the heel of reference foot rises while its toes are still in contact with the ground.
- Toe Off (Pre Swing): In this phase, the toe of reference foot rises and swings in air. This is the beginning of the swing phase of the gait cycle.
Swing Phase: The swing phase is that part of the gait cycle during which the reference foot is not in contact with the ground and swings in the air. It constitutes about 40% of gait cycle. It has three parts:
- Initial swing
- Mid swing
- Terminal swing
Support
- Single support: In single support only one foot is in contact with the ground.
- Double support: In double support both feet are in contact with the ground.
Terminology
- Step Length: It is defined as the distance between corresponding successive points of heel contact of the opposite feet. In a normal gait, the right step length is equal to left step length.
- Stride Length: It is defined as the distance between any two successive points of heel contact of the same foot. In a normal gait, the stride length is double the step length.
- Walking Base or Stride Width: It is defined as the side-to-side distance between the line of step of the two feet.
- Cadence: It is defined as the number of steps per unit time. In normal gait, cadence is about 100–115 steps per minute. Cadence of a person is subject to various factors.
- Comfortable Walking Speed: It is a characteristic speed at which there is least energy consumption per unit distance. It is about 80 meters per minute in a normal gait.
