GAIT CYCLE is important in walking.abnormalities

gait cycle

1. GAIT CYCLE ANAND LEO GEORGE

2. The normal human gait provides a smooth energy efficient transfer of the body through space. The normal bipedal gait is described as an interplay between loss and recovery of balance in which the center of gravity of the body located anterior to the second sacral vertebra shifts constantly Body conserve energy during gait by Q# mechanisms By minimizing the excursion of center of gravity By external moments to stabilize joints during gait cycle: By the efficient transfer of energy between body segments

3. Two content layout with table The normal gait cycle also known as stride describes the events occurring between two sequential floor contacts by the same limb Considering the presence or absence of contact for the limb being considered, the gait cycle is divided into two phases: 1. Stance phase 2. Swing phase

4. Stance phase Stance Phase Stance phase constitutes the first 60% of the gait cycle. It is further divided into four subphases: 1. Heel strike (initial contact), 2. Midstance 3. Push-off (terminal stance) 4. Acceleration ( preswing ). It also consists of five events known as critical incidences. ( i ) heel-strike, (ii) foot-flat, (iii) heel-off, (iv) knee-bend and (v) toe-off

5. Heel-strike: It constitutes 15% of gait cycle. C Critical event: This phase begins with heel-strike and terminates with foot-flat Midstance: It lasts for the second 15% of the gait cycle. During this period, hip and knee are bent preparing the limb for the swing phase. Critical event: It begins with foot-flat and ends with heel-off Push-off: The push-off subphase constitutes the next 25% of the gait cycle. During this period, hip and knee are bent preparing the limb for the swing phase Critical event: It is initiated by heel-off and terminates with kneebend Acceleration: It is the final period of stance phase and is 5% of the gait cycle. Critical event: It begins at knee-bend and ends at toe-off

6. Swing Phase The swing phase constitutes the remaining 40% of the gait cycle and begins at the point where the limb is unloaded and the foot comes-off the ground. Swing phase is subdivided into three subphases: 1. Initial swing—period of variable acceleration 2. Midswing —transitional period, 3. Terminal swing—period of deceleration and limb positioning

7. Initial swing: It constitutes 10% of swing phase. It commences with toe-off and continues as the foot is elevated from the floor in an arch by hip and knee flexion and the limb moves forward Midswing : It constitutes 80% of swing phase. It begins when the swing limb passes the opposite limb instance, the knee extends and the path of the foot is forward-swinging arc Terminal swing: It is the deceleration period, which occupies final 10% of swing phase. The force of gravity and the musculature of the limb smoothly break the forward moving swing limb; the heel strikes the ground.

8. Ankle Stance phase: Ankle function during stance phase is considered in terms of three rockers: 1. Heel rocker, 2. Ankle rocker, 3. Forefoot rocker. Heel rocker begins at initial contact (heel strike) and extends through the loading response. The planter flexion seen in the loading response is resisted by internal moment generated by ankle dorsiflexors muscle. The deceleration of ankle plantar flexion contributes to tibial advancement and shock absorption.

9. The ankle rocker occurs during midstance. The dorsiflexion at ankle is resisted by the internal moment generated by the ankle plantar flexor muscles. The deceleration of ankle dorsiflexion controls tibial advancement and contributes to stance stability by ensuring that the ground reaction force vector is anterior to the knee and posterior to the hip creating an external extension moment at each joint This promotes joint stability through ligaments without muscle action. The forefoot rocker occurs during terminal stance. Minimal ankle movement during forefoot rocker causes the heel to raise maintaining momentum and efficiently transferring energy between body segments

10. Swing phase: Active ankle dorsiflexion during initial swing helps in early swing limb clearance. In midswing , the internal dorsiflexion moment resists inertia and gravity forces to promote clearance. In terminal swing, the internal muscle moments position the ankle for initial contact so that the heels strike the floor first generating heel rocker

11. Knee Stance phase: In initial contact (heel strike) phase, full extension at knee provides stability for weight acceptance and contributes to optimal foot position. In loading response phase, flexion at knee joint is the principal means of shock absorption without compromising the knee stability. In midstance, knee extends to promote stability and advancement. Maximum knee extension is attained in terminal stance maintaining stability during forward progression. In preswing phase, the knee flexes and th Swing phase: Approximately two-third of knee flexion necessary for swing limb clearance occurs in preswing subphase. Further knee flexion occurs during initial swing, which is necessary for foot clearance as the ankle is in equinus at this point. Then for limb advancement, the knee extends . Optimal stride length is achieved by further knee extension by terminal stance. An internal flexion moment by the hamstrings decelerates the advancing limb before beginning the stance phase e limb is unloaded

12. hip Stance phase: In initial contact (heel strike), the hip is flexed to promote limb position. During loading response subphase, the ground reaction vector falls in front of the hip joint. The hip joint extends as the body advances in midstance phase. The hip stability is provided by anterior ligaments. Pelvic rotation contributes to apparent hip hyperextension at the end of stance phase. In the preswing subphase, the hip begins to flex and the limb is unloaded. Swing phase: In initial swing subphase, internal muscle flexion moments contribute to hip flexion. The hip flexion contributes to limb clearance early in swing phase and limb positioning for weight acceptance after the terminal swing subphase.