# Introduction and Phases of Gait cycle   GAIT

https://www.youtube.com/watch?v=jsx6zSiDrLE

[00:01] Dear students, welcome back.
[00:03] In the previous sessions, we have discussed about the posture, the two in static type.
[00:10] Now in this session, we are going to discuss about um gate.
[00:15] Okay, so gate is a uh dynamic posture.
[00:21] We can call it as dynamic posture.
[00:25] Okay, so in the previous sessions and all uh in the previous chapters, we have learned how individual joints and muscle functions cooperatively to maintain the body in the erect posture.
[00:39] And knowledge of that body structure and function in the static posture forms the basis for the study of human structure in a dynamic situation.
[00:51] Normally in a human locomotion, um, we got the opportunity to discover.
[01:04] how individual joints and muscles function in an integrated fashion to produce motion of the body as a whole.
[01:15] so knowledge of kinematics and kinetics of normal ambulation um provides um as for analyzing identifying and corrupting the abnormalities in Gate okay.
[01:32] so first of all in the in this chapter we are going to discuss about the kinematics of the gate okay.
[01:47] so before starting the kinematics first you should know what do you mean by gate.
[01:55] so gate may be defined as or described as a translatory propagation it is a translatory
[02:05] propagation of the body as a whole.
[02:12] produced by coordinated rotatory Ms of the body segments.
[02:15] which is produced by coordinated and um rotatory movements of the body segments.
[02:25] okay so normal gate is rhythmic.
[02:36] normal gate is rhythmic and characterized by alternating propulsive and retropulsive motions of the lower extremities.
[02:48] that is the movement so front and back.
[02:51] okay you can see the movements front and back movements of the lower extremities.
[02:57] that is called as alternating propulsive and retropulsive motions of the lower extremities that.
[03:06] means one limb is moving propulsive and another limb is moving retropulsive motions
[03:14] so with these movements only we can get the translatory progression of the body okay
[03:24] the alternating movements of the lower extremities essentially support and carry along the head trunk and arms okay
[03:36] that means here hat constitutes about 75% of the total body weight
[03:43] the head and arms combined to constitute about 25% of the total body weight while the trunk accounts for the remaining 50% okay
[03:59] so in the standing posture okay in the standing posture the H that is head arm and trunk
[04:09] is supported by both the lower extremities in Gate H.
[04:14] not only must be balanced over one extremity but also must be transferred from one extremity to the other extremity.
[04:26] okay so the weight of h plus and the weight of the swinging of lower extremity that means 10% of the total body weight must be supported on a single limb for example you can take this part.
[04:47] okay here in this stage so this limb is only uh in contact with the ground so now the entire body with not only the upper body and in addition with the other limb weight of the other limb is balancing on the other.
[05:11] Extremity okay that is the thing happened here.
[05:13] This stage is called as single limb support.
[05:16] So during gate cycle we can find uh number of single limb support.
[05:26] Okay that we are going to discuss.
[05:30] Okay although single limb support alternates with periods in which both lower extremities are in contact with the ground.
[05:39] So some phases will have both the extremities or in contact.
[05:49] Okay so gate plays more demands on the lower extremities than does the static posture.
[06:00] Okay.
[06:04] So these activities require coordination.
[06:11] balance intact kinesthetic and proprioceptive senses that is joint senses and integrity of the all the joints and muscles so for gate activities require coordination balance intact kinesthetic and proprioceptive senses and integrity of the joints and muscles so all together form to get a normal gate
[06:52] so for simplification um to understand about gate several authors have defined gate in terms of certain tasks and that much that is also used for some time so later According to some professional
[07:14] staff at um rla that is called as um ranco L Amigos Medical Center in California.
[07:26] they have given uh first three main tasks which are involved in walking so what is that is first is the weight acceptance so first one is uh the person uh the lower limbs has to accept the weight that is weight acceptance and next stage is the single limb support and uh next one is Swing limb advancement so these are the three points three tasks they have have established.
[08:02] first after that um some other uh investigators like winter also has proposed three main tasks for walking gate that include one
[08:19] is the maintenance of support.
[08:22] maintenance of support of H Against Gravity.
[08:28] okay next maintenance of upright posture and balance.
[08:34] and the third one is control of the foot trajectory.
[08:38] control of the foot trajectory to achieve safe ground clearance and a gentle heel contact.
[08:46] so these are the three uh main tasks which are um given by another um uh staff called winter.
[08:56] okay so finally um they have included all the above three and um.
[09:19] this and they have finally give five main tasks for walking gate.
[09:24] so what are those means?
[09:28] one is the main maintenance of support of H that is preventing collapse of the lower limb.
[09:37] that is the main task first task and maintenance of upright posture and balance of the body that is second one.
[09:47] and control of food trajectory to achieve safe ground clearance and a gentle heel or toll landing and also generate of mechanical energy to maintain the present forward velocity or to increase the forward velocity and the last one is the absorption of mechanical energy for shock absorption and stability or to decrease the forward.
[10:19] velocity of the body so maintaining balance and stability is very much important during ambulation and there is an increasing body of uh literature on what might be called subtasks of gate that are potentially destabilizing okay.
[10:48] so that thing we are going to discuss about but these are the five major tasks of gate so gate is an extreme L complex activity to analyze therefore gate has been divided into number of segments that make it possible to identify the events that are taking place so it is also worth noting that gate analysis is merely a special case of movement.
[11:21] analysis as a whole so knowledge of the terminology which are used to describe the events is necessary to be able to understand and analyze gate okay.
[11:36] so generally gate is described by using the activities of one lower extremity that is called as um reference extremity from the beginning to the end of one gate cycle.
[11:50] so now we are going to discuss about the phases of the gate cycle.
[11:58] so so here we are going to take one lower extremity as reference one.
[12:03] so here in this pick we are going to take the right lower extremity as a reference extremity.
[12:15] okay now we'll start with the faces of
[12:21] gate cycle the gate cycle
[12:24] includes the activities that occur from
[12:29] from the point of initial contact so now
[12:32] we are going to take this extremity this
[12:35] right extremity we going to uh take as
[12:39] reference one okay
[12:43] yes
[12:46] so the gate cycle includes the
[12:49] activities that occur from the point of
[12:52] initial contact of one lower extremity
[12:55] that is right one to the point
[12:59] at which the same extremity
[13:03] contacts the ground again so the gate
[13:07] cycle started with the initial contact
[13:12] okay so contact of that limb and there
[13:16] are number of series are going to takes
[13:18] place and the cycle will end up again
[13:21] with the same extremity which is going
[13:25] to land on the ground this is called as gate cycle okay.
[13:30] during one gate cycle each extremity passes through two faces.
[13:39] one is a single stance phase and swing phase.
[13:44] so this gate cycle will have two faces.
[13:45] one is stance phase and another one is Swing face okay.
[13:55] yes now we will see The Stance face here.
[13:59] so The Stance phase begin at the instant that one extremity contacts the ground.
[14:06] so here again the right we are going to take so this one is the heel strike and continues only as long as some portion of the foot is in contact with the ground.
[14:21] so if you can see so this
[14:25] extremity is going to contact UM in all the uh phases of the gate cycle okay.
[14:35] all these parts of the same extremity which is going to going to in contact on the ground.
[14:46] that faces of the gate cycle we are going to take it as stance face okay.
[14:54] during The Stance phase of gate some portion of the foot is in contact act with the supporting surface at all times okay.
[15:08] this stand face makes up approximately 60% of the gate cycle during normal walking got it yes.
[15:16] so the entire gate cycle is divided into stance phas and swing phase The Stance
[15:26] Phase forms the 60% of the gate cycle.
[15:31] Now we will see the swing phase.
[15:33] So the swing phase you can see so.
[15:37] The arrow marks indicating here you observe that.
[15:40] So the sing phase begins as soon as the toe of one extremity leaves.
[15:50] Okay, so this is the reference extremity.
[15:53] So here uh it is not in contact with the ground here.
[15:56] So it is leaving the ground and ceases.
[15:59] So when it is going to end up means Caesar just prior to heel strike.
[16:07] So here if you can see.
[16:09] So again here it is not in contact.
[16:13] So in all the time the limb is in on the air.
[16:17] Okay and it is not in contact.
[16:21] So it is going to end up just at the beginning of again the heel strike.
[16:24] This is called.
[16:26] As um swing pH is so it does not contact.
[16:32] So when the reference extremity is in the swing phase it does not contact the ground at any time.
[16:41] So the swing phase makes up 40% of the gate cycle.
[16:46] So so these are the two main phases of the gate cycle.
[16:50] One is the stance phase and the swing phase.
[16:53] So in the stance phase so the reference extremity he will be in contact with the supporting surface.
[17:05] Uh either full or partial contact throughout the phases of the gate cycle is called as uh stance phase.
[17:14] If you see in the swing phase the swing phase of the gate uh also defined as the period in which the foot of the reference.
[17:27] extremity is not in contact with the supporting surface.
[17:38] okay yes now here we can see um a period of double support.
[17:48] so we can find uh during this um gate cycle we can find uh some period that includes double limb support.
[17:59] normally we have taken the um reference extremity that limb is in contact in one phase and uh in another phase that limb is not in contact with uh that phase but during gate cycle uh one period of time which is having both the limbs are in contact during the gate cycle so that period of contact is called as double.
[18:28] limb support so it is a period of double limb support occurs in walking when the lower extremity of one side of the body is beginning its stand face and the lower extremity on the opposite side is ending its stance phase.
[18:48] so therefore there are two periods of double support in a single gate cycle.
[18:56] so not normally we are going to take um as one limb as a reference point isn't it.
[19:07] so so if we take this right leg as the reference point so here the heel strike is the initiation of The Stance phase isn't it stance phase of right leg okay right extremity and again it has has to
[19:29] end up.
[19:30] as uh heel strike is called one gate cycle of right extremity.
[19:35] but here we are getting two double supports in this period that means uh how it can occur.
[19:42] means so this one is the initial contact of the right one.
[19:49] but if you take if you consider the left one so for that left one that is the starting point of the Swing phase.
[20:00] okay so for the left L that is the starting point of the Swing phase.
[20:08] so we are getting two points of double support again.
[20:13] okay.
[20:15] so here this is the initial contact for the first double support in the second period.
[20:25] what will happen here is so the right right leg okay in the right leg it
[20:32] is going to start the swing phase and
[20:37] for the left leg it is the initial
[20:41] contact got it so during double
[20:46] support so because of this thing we are
[20:50] getting two periods of double support in
[20:53] a single gate cycle during double
[20:57] support both l lower extremities are in
[21:01] contact with the ground at the same
[21:05] time okay so both will contact at the
[21:08] ground at the same
[21:11] time
[21:13] okay
[21:16] yes here we can
[21:19] find um stance phase forms the
[21:22] 60% and swing phase forms the
[21:26] 40% of the total gate cycle at a normal
[21:31] walking speed stance of one leg and
[21:35] stance of opposite leg overlap for about
[21:40] 22% of the gate cycle okay so these two
[21:45] forms the 22% of the gate
[21:49] cycle okay so this is uh about the phes
[21:56] of uh um main phases of the gate cycle
[22:01] and each stance phase and swing phase
[22:04] will have
[22:06] subdivisions those subdivisions of the
[22:09] gate cycle we are going to discuss in
[22:11] the next session thank you