what's up guys today we're going to be talking about the gait cycle and in this video we're just going to tackle the normal gait cycle but stay tuned for some more videos on some abnormal gait patterns all right to get us started here's an overview of one gate cycle and we define one gate cycle as initial contact to initial contact usually now you can actually pick whatever starting point that you want and when that same point comes around again that's one complete cycle on the same leg uh since gate is continuous it doesn't really matter where you start but most of the time you'll see people starting with initial contact for ease it's a pretty noticeable phase and it's a good point to get your mind wrapped around what's happening during gait there are a few things that our body has to do in order to keep us moving forward and we're going to break that down into three tasks three functional tasks the first one is going to be weight acceptance you actually have to put your foot down to start accepting the weight the next one is single limb support and that's going to describe when we have one limb that's responsible for all of our weight bearing and then last we have to move our leg forward in order to progress and get to the next gait cycle so we are going to go through the gait cycle twice in this video the first time we're going to leave out muscles and we're just going to talk about what happens in each phase then the second time we will add in our muscle activity we have two sets of terminology the rancho los amigos which is going to be listed first and traditional terminology which is going to be listed in our parentheses here uh it's important to know both of those i think you're going to see the rancho terminology used a little bit more in the real world but the npte may still ask you about both kinds so try to get used to it if you can okay so let's start with our initial contact which is also known as heel strike and in this phase we are starting to contact the ground with our supporting limb usually the heel is what strikes first if we have a normal gait pattern and we are initiating something known as the heel rocker so essentially we're going to roll over our heel until our foot is flat okay second response is going to be loading response that's when our foot starts to go flat onto the ground and we start to accept weight so we're still doing task number one here and in this position we need a lot of weight bearing which means we need stability we're going to have to absorb shock as we put our foot down and start to put our body weight on our limb and we as always we still have to be moving forward through the whole cycle mid stance will follow loading response and we are transitioning to our second task so now one limb is going to support our entire body weight and as you can see here we're almost directly in line with our body over our foot as we transition to terminal stance we're still in our single limb support phase and this is where we're going to transition from our heel rocker to our forefoot rocker and so that just means that we've rolled over our heel and now we're going to start bending at those mtp joints in order to initiate that forefoot rocker all right so during pre-swing we now transition into task 3 which is going to be our limb advancement this is going to prepare us to unweight our limb so that we can start to take it off the ground and swing it forward so during our initial swing here we've now picked the limb up and we are initiating movement in our swing phase this phase is going to involve clearing our foot from the ground and we're actually almost three quarters of the way through our gait cycle before our foot even leaves the ground in mid-swing we're still advancing that limb forward we don't want to pick the foot up too much because our body is trying to be smart and conserve energy so we're just going to basically barely clear the foot so that we don't have to use as much muscle recruitment and we'll talk about that when we talk about our muscles and terminal swing we are starting to slow our leg down so the limb is still advancing but this is going to be the last phase of our normal gait cycle and the body has got to prepare itself for another gait cycle on the opposite extremity so here's a wrap up of that normal gait cycle with our three phases that we talked about are three functional tasks we've got weight acceptance we have single limb support and we have limb advancement and all three of those tasks have to occur during each gait cycle on each limb so that we can efficiently and effectively progress our body forward okay so let's go on to our muscles as those are a huge part of our gait cycle but what we're going to do is try to break it down into two ideas that we can use during each phase so the body can either generate energy in order to move a body part or it needs to remove energy in order to control our movement and our progression forward as we go through again our normal gait cycle so in this round of looking at the gait cycle we're going to look at two phases in sequence because as we know the gate cycle is continuous and we've got movement consistently progressing so we sort of want to think about it in those terms as well that'll make it a little easier we also are going to go joint by joint and we're going to look at the hip first the knee second and the ankle third so that you have a little bit of a breakdown as you're trying to study everything that's happening during the gait cycle because it's a lot so hopefully this will give you a way to make it a little bit more manageable and or make it easier to study that being said i will tell you you're probably going to have to roll through this video a couple of times by a couple i mean five or more times in order to really understand each phase of the cycle all right so starting with initial contact to loading response we see that the hip starts in flexion at initial contact and moves to a little bit of extension in our loading response so we know that our hip is extending but we need to know are we generating energy to extend it or are we removing energy to control the hip extension in this case we're moving quite a bit from flexion to extension and we don't really have any momentum going that we know of so that's going to require that we are using our concentric hip flexors to get that hip moving into extension if we look at the knee we're starting in the relative knee extension and we're going into slight knee flexion it's a little hard to see on the picture but what we know is as our foot is flattening to the ground during our loading response we're also accepting our weight that's our functional task that we talked about so since we have to accept some body weight we're going to need a little bit of shock absorption so if you think about it that way when we move our knee from extension to flexion we're doing knee flexion but we're going to have to control this motion so we need our eccentric knee extensors working for us in this phase transition finally if we look at the ankle we start in either neutral maybe a little bit of dorsiflexion and we're moving to some plantar flexion in order to put our foot flat on the ground again we've got gravity kind of assisting us as we're going so we're going to think more control during this phase than generation and we see that we need our eccentric dorsiflexors to help us control that plantar flexion down so from initial contact to loading response we got the hip extending the knee flexing and the ankle plantar flexing but we also have to think through are we generating or are we removing energy so at the hip we've got to generate energy to extend it at the knee we've got to control it with our eccentric knee extensors and at the ankle we also have to control our laureen down to the ground with our eccentric dorsiflexors moving on we are going from loading response now to mid stance so let's start with the hip again and we still look like we're going into relative hip extension we also don't really have any momentum that we have gained thus far so it should be the same we should require our concentric hip extensors to get that hip extension when we transition to the knee the knee tends to be the tough one it's always the confusing one because it's the joint in between and because it has a lot of transition going on so in this case we got slight knee flexion that we had had in our loading response and we definitely need to move to knee extension because we need a straight limb so that we don't collapse when we're in mid stance so we actually got two things going on at the knee we have extension as our motion but we are coming off of an eccentric um transition and we now need to give a brief concentric to our knee extensors in order to get that straight leg for mid stance to bear our full body weight finally the ankle is still moving into relative dorsiflexion because that tibia is advancing forward over the talus all the way from initial contact through mid stance so if you think about advancing we've got some momentum going there so we still need control and that's going to require again our ankle eccentric plantar flexors to be working so from loading response to mid stance we've got the hip continuing to extend we've got the knee transitioning from flexion to extension and we've got the ankle continuing to dorsiflex mainly through momentum so we still need to generate energy at our hip to extend it we're gonna have to generate extension at our knee to support our leg and that's going to require that transition from our eccentric to our concentric muscles and finally we need to control that tibial advancement so this is going to be again our eccentric plantar flexors at work so from mid-stance to terminal stance we still have hip extension going on and it still needs to be generated so we've got those concentric hippic sensors the knee is where we're still getting a little bit more complicated and in this case we've got that knee extension that we had gotten in mid stance in order to support our body weight and we're moving into some slight knee flexion in our terminal stance so we had said our concentric knee extensors were working but if we're going to do knee flexion we're going to have to have a little bit of concentric knee flexors after that so our knee is again transitioning from concentric knee extensors to slight concentric knee flexors so it's still concentric but just a different muscle group and then finally from mid-stance to terminal stance we are going to have a little bit of plantar flexion and this is where we start to push off the ground in our terminal stance so we need to generate our energy we are finally going to be using some concentric ankle muscles and we're going to be needing our concentric plantar flexors so from mid stance to terminal stance we've got the hip continuing to extend the knee is going to slightly flex and the ankle is going to transition to plantar flexion we need a lot of generation this is kind of the middle of our stance phase so we got to go from behind us to starting to push off for our swing phase so we've got to generate the hip we've got to generate the knee and we've got to generate the ankle everything is going to be concentric in this transition right so from terminal stance to pre-swing the picture is not a lot different between the two phases so again it can be a little difficult to kind of picture what's going on but we have our hips starting to go into flexion because we need to now bring that leg that we just stood on through to start our swing phase so we still have concentric muscles going on but this time we've got hip flexors working our knee was in flexion and it's going to go to a little bit more flexion throughout the swing phase the knee needs about 60 degrees of knee flexion which is actually quite a bit so we know we're going to be generating a lot of energy at the knee in the next couple phases that would require our concentric knee flexors here and finally we've got our ankle that is still pushing off the ground and so we are still needing our ankle plantar flexors here working concentrically and that will rapidly transition in our next phase that we'll talk about but from terminal stance to pre-swing we've got our hip moving into some flexion our knee into some flexion and our ankle continuing to plantar flex and it's actually going to have a peak plantar flexion activity so again we're in a high generation phase we've got to generate a lot of energy at the end of our stance phase so that we can start swinging that leg all right we are officially on to our swing phase so from pre-swing to initial swing we still have some hip flexion occurring so those concentric hip flexors we still have our knee flexion because remember we have to hit our 60 degrees so we've got concentric knee extensors and we still have a little bit of concentric plantar flexion occurring because we just bursted our foot from the ground in plantar flexion and so we're still finishing that phase and that's why we're still on concentric plantar flexion that's going to change real quick though as we'll see in the next one so from pre-swing to initial swing the hip is going to continue to flex we need the knee to continue to flex and the ankle is also going to continue to plantar flex but it's on the end of our plantar flexion so we just pushed our foot off the ground that's going to be sort of the end of that plantar flexion phase for the moment all right as we are starting to get into our full swing we still have our hip flexing so we're using our hip flexors we still have our knee flexing so we're using our knee flexors and now we have some ankle dorsiflexion going on right because we've actually got to clear that foot from the ground so we went from that plantar flexion that we needed to push off the ground now we need some rapid dorsiflexion happening again a lot of generation of energy occurring so from initial swing to mid-swing the hips flexing the knee is flexing and the ankle needs to start dorsiflexing and rapidly so we're gonna have generation of hip flexion generation of knee flexion and ankle dorsiflexion okay so from mid-swing to terminal swing our hip is still flexing hip stays pretty constant our knee is still flexing but we're finally getting to the end of that flexion that we needed to clear and we still have to clear that ankle as we're swinging the leg through so our dorsiflexors are still going to be working here now the caveat for the knee is that once we are done with flexion in order to swing the leg through and in order to clear the ground our body is going to conserve a little energy by turning some of those knee muscles off and that sort of happens from mid-swing to terminal swing and as we start to move into our initial contact of the next leg so from mid-stance to terminal stance we still have flexion at all of our joints and most of it's going to be generation but the hip and the ankle are going to do the most work the knee is going to be turning off throughout some duration of this phase finally we have our terminal swing to initial contact so we're ending one leg gait cycle and then we are using our other leg for our next gait cycle now we've just come off of our swing phase where we had a ton of energy going because we generated a lot of energy throughout that phase so we need to control it before we hit our next initial contact it's going to require a lot of eccentric muscle work starting with the hip where we're going to see our eccentric hip extensors working to control this hip flexion that we're seeing from terminal swing to ic and our knee is going to do another transition moment so we need a little burst of concentric knee extensor activity to get our legs straight again but at the same time we need some control from our hamstrings so that we don't hyperextend and so that we're ready to contact the ground again finally that ankle dorsiflexion is still working because we still want to make sure that we don't trip over our foot at the very end of our gait cycle so we see some concentric dorsiflexion action so from our terminal swing to our initial contact the hip is going to need some control as we move into flexion but we're going to need to generate and control our knee kind of at the same time and we are going to need to continue the generation of our ankle dorsiflexion all right so hopefully that helped break the information down a little bit i know there's a lot so feel free to watch this a couple of times last thing i want to leave you with is a couple of concepts that might help you wrap all of this together especially when we add those muscles into our gait cycle so our first tip is that muscles will always turn off when they are not needed to counteract our ground reaction forces your body's smart your body's efficient and it's going to want to conserve as much energy as possible whenever it can then our muscles will always need to be creating our forward progression for us so when we walk we're usually moving somewhere and that only happens because of our muscle energy so besides helping us generate motion our other muscles are going to need to help stabilize us because we have to support our entire body weight while moving through air and through gravity and they play a pretty big role in that okay so if a movement of a lower extremity joint is occurring in the same direction as the ground reaction force then we don't need a constant concentric contraction uh because we don't need to generate any energy the ground reaction force is our energy and that's what's generating however that's where we are usually seeing our eccentric contraction because we're going to probably need to control that ground reaction force conversely if a movement of a lower extremity joint is occurring in the opposite direction as our ground reaction force then we usually need that concentric contraction to overcome that force so i hope this helped a little bit as you are reviewing your muscles go ahead and start thinking through uh which particular muscles are acting at which point so this powerpoint was just talking about hip extensors knee flexors and general categories but you really want to know well is it my glutes working is it my quads working as you're going through so that's a little bit of an extra tip see if you can add that in and i hope this helped as always don't forget to click the links below to access a short quiz and some review questions