Biomechanics gait

gait

1. GAIT PHASES K.SOUNDARARAJAN

2. OBJECTIVES Introduction Gait cycle Phases of Gait Stance Phase Swing Phase Gait Terminology Conclusion K. Soundararajan, SRIHER 2

3. GAIT AND PHASES OF GAIT CYCLE

4. INTRODUCTION Human locomotion or gait may be described as a whole produced by co-ordinated rotatory movements of body segments Normal gait is rhythmic and characterised by alternative propulsive and retropulsive motions of the lower extremities The alternative movements of the lower extremities essentially support and carry along head, arm and trunk (HAT) HAT constitutes about 75% of the total body weight Head & arms – 25% Trunk _ 50%

5. In standing posture the HAT is supported by the lower extremities, in gait the HAT is not only supported but also transferred from one extremity to other. These activities require co-ordination, balance intact kinesthetic and proprioceptive senses, and integrity of the joints and the muscles. Gait patterns reflects the persons occupation, body structure health status and personality as well as many other physical and psychological attributes. Knowledge of the proper gait pattern is useful for analysing, identifying and correcting abnormalities in the gait.

6. GAIT CYCLE : Gait is forward propulsion of the body by the lower extremity with the co ordinated rotated movements of body segments. Gait cycle includes the activities that occur from the point of initial contact of one lower extremity to the point at which the same extremity contacts the ground again. During one gait cycle each extremity passes through two phases 1. Stance phase 2. Swing phase

7. STANCE PHASE : The activity which occurs during the foot having the contact with the ground The stance phase begins at the instant that one extremity contacts the ground, during the stance phase some portion of the foot is always in contact with the ground.

8. SWING PHASE : The activity which occurs during the foot when is not having the contact with the ground

9. K. Soundararajan, SRIHER 9

10. In normal walking the stance phase contributes 60 percent of the gait cycle and the swing phase 40 percent. When the one extremity begins its stance phase, another extremity ends in the stance phase. The traditional method and Racho Los Angious (RLA) medical center, California , definies the activities during stance and swing phases. K. Soundararajan, SRIHER 10

11. Subdivisions: Heel strike or Initial contact Foot flat or Loading response Midstance Heel off or Terminal stance Toe off or pre - swing

12. 1. HEEL STRIKE or INITIAL CONTACT : Initial contact refers to the instant at which the heel of the leading extremity strikes the ground. In normal gait the heel is the point of contact. In abnormal gait whole foot make contact with ground rather than heel. EX: Here Right side heel strikes the ground

13. 2. FOOT FLAT or LOADING RESPONSE : Foot flat occurs immediately after the heel strike and is the point at which the foot fully contacts the ground (7%) Ex: The 70% body weight is now supported by the right leg this position is more stable and it is also known as the double support phase

14. 3. MIDSTANCE: Midstance is the point at which the body weight is directly over the supporting lower extremity (30%) Ex: Midstance begins when the contra-lateral limb (left) is lifts off the ground and the body is has progressed over and ahead of the supporting extremity

15. 4. HEEL OFF or TERMINAL STANCE: Heel off is the period from the end of the midstance to a point just prior to the heel strike of the opposite limb (40%) Ex: Heel off is the point at which the heel of the right leg leaves the ground and left heel strike the ground

16. 5. TOE OFF or PRE-SWING: It is the instant at which toe of the foot leaves the ground (60%) It is the point at which only one toe of the ipsilateral extremity is in contact with the ground The period from heel off to toe off often is referred to as the push off period of the stance phase Ex: Right foot toe alone strike the ground and left foot goes for mid stance

17. SWING PHASE : Acceleration or Initial swing Midswing Deceleration or Terminal swing

18. ACCELERATION or INITIAL SWING : Toe leaves the ground and continues until the mid swing or point at Which swinging extremity is directly under the body Ex: acceleration begins once the toe of the right limb leaves the ground Now the 80% weight of the body is supported on the left limb.

19. 2. MIDSWING : Midswing occurs when the ipsilateral limb passes directly beneath the body and from end of acceleration to beginning of deccleration . Ex: The right leg is going for maximum flexion and and left knee goes for the extension and locking occurs this phase is known as the single limb support phase

20. 3. DECELERATION or TERMINAL SWING : Deceleration occurs after the midswing when the limb is in preparation for heel strike Ex: when the right leg is extending and preparation for the heel strike The right foot strikes the ground and the knee is full extension

21. STANCE TIME : It is the amount of time that elapses during the stance phase of one extremity in a gait cycle SINGLE SUPPORT TIME : It is the amount of time that elapses during the period when only one extremity is on the supporting surface in a gait cycle. DOUBLE SUPPORT TIME : It is the amount of time that a person spends with both feet on the ground during one cycle. % increases in elderly people ( balance disorder) % decreases as speed of walking increases

22. STRIDE LENGTH Stride length is the distance between the point of heel strike of reference limb to the next heel

23. STEP LENGTH Step length is the distance between the two successive points of contact of opposite extremities (right & left foot)

24. CADENCE : Cadence is the number of steps taken by a person per unit of time Cadence = number of steps/min 180 steps/ min = Running 110 steps/ min = Normal adult WALKING VELOCITY : It is rate of linear forward motion of the body. Which can be measured in km or in miles Walking velocity = distance walked/time

25. DISCUSSION …..

26. REFERENCE

27. Thank you