all right we're back to finish up our neural PowerPoint and talk about some of the things that have to do with the neural system but now that we know some information about the neural system what I want to look at now is how can you manipulate some of the things from the neural system to see a certain outcome or how does all of this information apply to exercise principles so first off here we're going to look at flexibility what is flexibility is just simply put the range of motion about a joint so for my shoulder for instance my full range of motion about a joint whether that's active range of motion or passive range of motion meaning that somebody or an external uh source is taking my joint through that range of motion it's going to be very specific to the Joint itself based on a lot of different things like joint structure age sex the muscle and the tension within the muscle and other factors we'll see in just a minute but the neural system plays an important role in flexibility and our ability to improve flexibility so looking at flexibility versus Mobility here what do we want to focus on flexibility is just simply put the range of motion about a joint whereas Mobility is the ability to produce Force within that range of motion so knowing the definitions there which one would you focus on which one is going to help you to improve your activities of daily living the quality of life and maybe somebody that's in the geriatric population as you're a therapist or a trainer or strength and conditioning coach in your field so what we really want to focus on is the mobility I want the functional range of motion I don't want to just become a contortionist and move my body through all these different angles and ranges of motion want to be able to produce Force within those ranges of motion so General recommendation here is perform two to five stretches on each of your muscle groups and that effect will last anywhere from one to two hours factors that affect your flexibility here we see joint structure whether it's a ball and socket ellipsoidal joint a hinge joint like your elbow age sex what happens to flexibility as you get older as age increases flexibility decreases who's uh more flexible generally females are more flexible than males muscle tissue all of these things have a factor a role in your flexibility the neural control when it comes to things like the activity of the spindles or the activity of the GTO are they imbalance within each other or do you have a overactivity of your muscle spindles remember spindles are protecting you from over stretching so what they'll do is excitatory signal comes back to the muscle if that happens the muscle contracts that's going to decrease my flexibility muscle bulk will limit flexibility your activity level for sure and then something known as stretch tolerance so you can really think of this as pain tolerance so if I take my joint all the way to the end of its range of motion to the point of discomfort everybody's going to be a little bit different on the level of discomfort that they can withstand so it's very similar to pain tolerance there stretching implications so we have different forms of stretching we're mainly going to focus on these two right here proprioceptive neuromuscular facilitation and static stretching so static stretching is go through a slow sustained stretch and hold that stretch at the point of discomfort so the best example of this is going down to stretch my hamstrings in the toe touch so I go all the way down to the point of discomfort I'm going to hold it there for a certain amount of time and then come back up out of that stretch so I'm slowly stretching the muscle we'll talk about some some implications and why slow in just a second and then PNF stretching is a technique that manipulates the information the knowledge that we have on spindles and GTO to improve your range of motion and very important for improving Mobility the big one that I want to focus on ballistic stretching here is using repetitive bouncing so again if I were to go down into the toe touch where I'm going to sit there at the end of that range of motion and repetitively bounce in that position it's not a highly recommended technique because you're at risk of injury there and then Dynamic stretching we don't spend a lot of time talking on because this is just using sport specific movements to take your your body segment or your joints and muscles through the range of motion that would be used in that exercise or in that uh competition this is where the uh principle of specificity comes back into play now with stratic static stretching so static stretching requires no voluntary muscle activity instead it relies on an external Force so what could you think of would be an external Force we could think of this as being something like a partner you could say gravity is an external Force again if I'm leaning in this direction gravity is going to pull my body down so that would be an example um something like bands elastic bands could be an external Force to pull my joint into that range of motion but the big recommendation right here is to do it slow so if I go down into the hamstring stretch and touch my toes I want to do it very slowly because what that does is it prevents the stretch reflex remember if say this is going to be a horrible drawing here but this is my upper body back lower body I've got my hamstring muscles right here and I'm G to Bend forward into this position so my arms and my head here you're going to bend into that position so I'm stretching my hamstrings if I do it too quickly that's a rapid overstretch of the hamstring so spindle muscle spindles are going to be activated send that signal to my spinal column say hey look you just stretched it too quickly and you stretched it too far excitatory signal is going to come back to the muscle and it's going to end up stimulating that muscle to contract which then is going to bring my body back up out of that stretch so I have to do it slowly so that I prevent the stretch reflex from happening hold it for about 15 to 30 seconds and you get about that one to two hour effect from it I encourage you to do this right here in class always have people get up and do this so that you can experience what this is talking about with autogenic inhibition so if I erase I'll try to erase some of this so we can look at this picture here come on get rid of all of this stuff autogenic inhibition means that I'm inhibiting the same muscle or the muscle of focus so say muscle of Interest so in this stretch right here my hamstring would be my autogenic muscle because that's the muscle that I'm interested in it's my muscle of focus for the stretch so as I go down into this motion right here if I do it slowly and then I get down there to the point of discomfort and say that point of discomfort for me is about right here here all the way down at about a 90° angle and I'm able to kind of Reach Out And Touch my toes or touch the floor if I hold that for about six to 10 seconds since I'm I've prevented the stretch reflex from happening now I've stretched my muscle out all the way out to really it's kind of its Max Capacity and the point of discomfort I'm going to stimulate gto's because think again it's pull pulling all these muscles are attached so it's pulling this muscle which is stretching this tendon so that tendon is going to send information back to the CNS and say hey I've got a lot of tension going on right here I need you to send an inhibitory signal back to my muscle so it sends an inhibitory signal to the hamstring muscle and what that'll allow you to do is actually stretch a little bit further into that range of motion so why I say uh or the recommendation to try and experience this is I want you to stand up go down into the hamstring stretch and hold it there at the point of discomfort where it's really kind of getting a little bit painful quote unquote for about six to 10 seconds count to 10 and then try and go a little bit further and I guarantee you you'll be able to go a little bit further into that stretch and that's because of the GTO down here at the uh distal end of the muscle causing a relaxation signal being back to your hamstring now have you ever stretched your hamstrings too long so say you hold it for 30 to 60 seconds what can end up happening is something called myoclonus which is a muscle spasm so if I draw my body again my arms and my legs hamstrings back here and I stretch and I hold it for too long now my GTO are sending that signal back to my central nervous system for inhibitory but my muscle spindles are also saying look buddy you have stretched long enough and I don't I need you to stop because I'm trying to protect you from over stretching so it sends that signal back to your central nervous system excitatory comes back to the muscle so now I have both excitatory and inhibitory com to my muscle and it's going to make it go into this spasm because I'm getting a excitatory inhibitory which means contract relax contract relax and it's going to make it twitch like that so if you're ever standing up and you touch your toes in the hamstring stretch that's what's making your leg shake if you hold that stretch too long answer some questions here does pre-exercise static stretching reduce the uh the risk or severity of an injury that used to be uh conventional knowledge to say that stretching static stretching before exercise will reduce the risk of injury but what we end up seeing now is it actually increases the risk of injury which is why preexercise we recommend Dynamic stretching actually actively taking your uh joints through the range of motion with static stretching if I just go and I just move it all the way to the end of the range of motion and hold it there what I'm doing is stretching those tendons and ligaments and that can increase something known as joint laxity which is the looseness of the joint so if I'm increasing the looseness of the joint think about the knee joint specifically where you have the MCL the LCL PCL and ACL and I'm an athlete that's in a uh sport that requires me to plant my foot and cut turn aggressively and cut and go in a different direction if my knee joint is loose then that could increase my risk of injury there does it cause a decrease in power and muscle strength most research says yes that's what's known as the stretch induced Force deficit so been shown in vertical jump and in strength exercises that if you take your arm or take your leg or whatever it is and put it into the full range of motion and hold it there because you're stretching out those tendons and ligaments and increasing joint laxity you remove the ability to have that elastic recoil at that joint and of those muscles so that can affect the actual recoil motion of the muscle think about for a vertical jump I don't do a vertical jump from standing in an upright position there's always a counter movement first which means before I jump up as high as I can I'm going to go down so that I can get that elastic recoil and explosively move up if I hold my joints of my lower body at the point of discomfort and stretch all of that out it's just like a rubber band if I were just to sit here and hold it for a long period of time when I let it go my elastic recoil is not going to be as great as if I were to just take it and then let it go so you end up decreasing your Force production because of it does it prevent delayed onset muscle soreness absolutely not can help afterwards to kind of increase and improve some blood flow to push all the metabolites and byproducts out but it's not going to prevent the muscle soreness because that's coming from the uh damage within the muscle tissue those micro TI does it decrease balance yes because of the joint laxity does it decrease your reaction time yes that goes back to the strength induced uh or the here the stretching induced Force deficit forgot my terminology there so decrease in reaction time because we don't have the elastic recoil of the muscle tissue are women more flexible than men yes they absolutely are because of the muscle bulk and the structure of the muscle tissue does resistance training affect flexibility if you don't do flexibility stretching training whether it's PNF stretching static stretching dynamic in combination with resistance training then yes because muscle bulk if uh let's see if I could spell if muscle bulk increases then flexibility is going to in turn decrease all right here's PNF stretching I absolutely love PNF stretching because we're manipulating things that we know about muscle spindles and Gogi tendon organs to be able to improve Mobility about a joint so what PNF stretching does is it'll it forces you or makes somebody contract during the range of motion and knowing the information that we know about the GTO that causes an inhibitory response autogenic inhibition goes to that muscle of Interest so we're going to flip back and forth between some slides here these down here are videos that I encourage you to go watch because it's showing you both techniques of PNF stretching so your different techniques here we have the hold technique and we have the contract technique so this is say an athletic trainer a strength coach or a physical therapist practitioner whatever it is this is your athlete here what the trainer or the practitioner is going to do is they're going to H take this leg up into the passive range of motion meaning that there's no I'm not asking the athlete to contract and bring their leg up into this position I'm going to take their leg into that position to the point of discomfort and create this hip flexion here now in the contract technique what I'm going to ask to do is I'm going to say contract your hamstrings and your glute muscles and I want you to drive your foot all the way back down towards the ground what I'm going to do is I'm going to provide a resistance against that so that it's not a fast movement and I'm making you contract your hamstrings very hard to push against me and drive that foot back down so I'm going to hold it and as they're pushing and pushing and pushing I'm going to slow slowly let their foot come back down towards the ground what I did during that motion is I've stimulated or made them stimulate their GTO GTO send the signal to the spinal column which then sends the inhibitory signal back to the hamstring muscle so now our second round I'm going to lift the foot back up into that range of motion and instead of stopping right here because the hamstring is inhibited it's going to let me go further into the range of motion and I get a greater flexibility range of motion about the joint but what I've done now is I've trained Mobility because within that range of motion I've made them create muscle contraction and produce Force within the range of motion there now the other technique is the hold technique let's get rid of all of this stuff what I'm going to do is I'm going to take their leg passively up into this range of motion just like the other one but with the hold technique I'm going to say contract and I want you to try and push your foot back down to the ground but I'm not going to let you I'm going to Hold Your Position right here so now they're pushing as hard as they can to try and drive the foot back down but I don't let them change the joint angle so it creates an isometric contraction of the hamstring GTO are stimulated sends an inhibitory signal back to the hamstring muscle makes the hamstring muscle Rel relax then I tell them after about 10 seconds okay you can relax now and I can push that leg further into that range of motion like that and now again I've trained flexibility and Mobility through this technique this is a primary area that you'll see it done uh is with the hamstrings and the glute muscles but you can also see it done on the chest so what you would do is provide resistance pulling backwards here and they would try and bring their hand hands together in the front of the body and then after that you tell them to relax and you can pull the arms further back into that range of motion same thing here with the butterfly stretch you're going to push down on their knees and they're going to try and bring their knees up so because of that stimulating GTO inhibitory comes back um and we're able to stretch further and push these knees down further to the ground shoulders would be very similar to this but instead of arms out stretched like this I'd have them put their hands behind their head and I pull backwards on their elbows and then they pull their elbows closer to the front of the body and then relax and go back into the stretch and then the quadricep and hip flexors is similar to that if you've ever seen somebody in a Superman exercise or Superman stretch very similar to this right here but they're in the prone position so they're lying on their stomach and we're pulling the leg back into into hyperextension they pull the knee back down to the ground and then we pull it further into hyperextension that gets us something called plyometric so Plyometrics is very important to talk about because you're seeing more and more of it in the exercise industry now and it comes from manipulating knowledge that we have about muscle spindles and Gog tendon organs so plyometric calls on the stretch reflex and what it does is it makes you fire more of your motor units we get this elastic recoil or what's known as rebound training uh because of the Ecentric loading of your muscle tissue it stores elastic energy like a rubber band so then when I voluntarily contract my muscles to say jump up not only do I get the strength of the contraction but I also get the release of that elastic recoil energy to explode up in that manner so plyometric all comes from this stretch shortening cycle which is abbreviated as the SSC so the stretch shortening cycle has three phases it has the Ecentric phase the amortisation phase and the concentric phase so Ecentric phase is the lengthening of your muscle tissue and when you lengthen the muscle tissue especially when you forcefully lengthen it you store elastic energy and something known as the SEC which is the series elastic component of your muscle tissue so this is going back to basic muscle physiology where Titan and the winding the spring like elastic action of Titan comes into play but again because you forcefully lengthen the muscle tissue you're stretching it rapidly so we stimulate muscle spindles this is again going back to our previous uh part of this lecture where gamma motor neurons are going to come into play all right then uh there's a brief pause in between the Ecentric phase where you're stretching the tissue and then you contract the tissue so that pause allows your muscle spindles to send the information to your spinal column and the excitatory stimulus to come back to your muscle tissue it says here Alpha motor neurons transmit that information the excitatory stimulus back to your muscle and cause it to contract and then the concentric phas is when we concentrically contract and shorten the length of the muscle but not only are you getting the contraction of your muscle you're also releasing the elastic energy that was stored in phase one so you get that rebound action look at it like this this is my starting position up on the box when I jump down off of the Box hopefully you don't land on the floor with your knees locked out so your knees bend a little bit the bending action of your knees stretches your leg your muscles of your legs in here I know this red on red so it's hard to see but it stretches those muscles so that's the Ecentric phase where we're storing elastic energy here and we're stimulating spindles and then right in between the rebound or right in between the Ecentric and the rebound concentric we have this pause at the bottom of that motion so you're allowing the spindles to be able to send the signal back to the muscle and excite the muscle and then during this phase during the Fire or the concentric phase phase three here this is when we voluntarily contract the muscles of the leg and we release this elastic energy like a rubber band and create that recoil action so that's the stretch shortening cycle and that's where plyometric exercises come from is the knowled of all of the stretch shortening cycle and how the neural system works manipulating that to make ourselves more powerful all right that gets us to something uh with low back pain so interesting facts about low back pain about 80% of Americans will experience low back pain by the age of 50 you may have experienced some of it already and the underlying causes listed here are really interesting coming from a lack of balance strength in the core particularly in the abdom abdominal muscles and the hamstrings usually what you end up seeing is tight hip flexers and weak hamstrings and we'll see what that does to your structure of your anatomy in just a minute but it can also come from poor flexibility of the low back excessive body weight and poor posture unfortunately we are so far advanced in technology right now that most people spend a lot of their day in this position right here shoulders rolled forward back arched over and that causes the posture of the body to stay like this throughout the day if I'm sitting at my desk like this most of the day my body is over time going to adapt to that position so my muscles on the anterior side are going to get tight and pull me into that position so that's pulling my ab tightening my abdominal muscles tightening my hix and weak weakening the posterior side so all of these factors come into play this right here low back pain is the number one reason why people go to see a physician in the United States so it's the number one reason for physician visits in the United States and out of all of these factors and underlying causes right here there's one that is the number one cause of this number one reason the number one cause is tight hip flexors so what happens with tight hip flexors if these are my hip flexors right here and they're attached on the anterior side of my body if they get tight and they shorten up they're going to cause anterior pelvic tilt so it's taking my pelvic girdle that's like this my hip flexors are going down and it's going to cause my anterior pelvis to tilt down now what that does is that pushes the backside of your pelvic girdle up we naturally have a little bit of a lordotic curve in our lumbar spine but by creating this motion of our pelvic girdle we're pushing the back side of the spine and it's causing this excessive lordotic curve which creates compression at your inner vertebral disc here in between the spine of your vertebrae so now think about all during the day if I've got this lordotic curvature of my back and I've got compressive forces right here and then I'm moving throughout the day and I turn and I twist and all of that stuff it creates sheer stress or in other words it creates friction in my lumbar spine that's going to in turn stimulate the inflammatory response which leads to inflammation of your lower back and that's where lower back pain is coming from not in all cases but it's the number one cause of low back pain in the United States now say you have an imbalance of your musculature your hamstring the back side of your body is tight and you've got weak abdominals and weak hip flexors here that's going to pull your pelvic girdle in the opposite direction so what that does is it stretches out the posterior side of the back and and the other thing that you're going to see if my leg continues down to my foot right here in the normal position this is neutral position what you're supposed to look like anatomically here every time your foot hits the ground the forces absorbed from the ground are supposed to travel up your leg through the femur through the hip and be absorbed all the way through the body because force is going to travel in a linear path in this position right here this posterior pelvic tilt we're going to go to where Force so your foot hits the ground forces are going to travel all the way up here to where it can't travel linearly any further so that means that all of this force is going to be absorbed right here in the hip and that's where that individual is going to feel the pain in this case right here with forward shifted pelvis and what we call a sway back so sway back looks like that right there forces is absorbed by the foot are going to travel up through here up we can't go linearly anymore so it's all going to be absorbed right there in the knee and that individual is going to have knee pain so a lot of different things you can gather just looking at the anatomical structure of the body and the muscle tightness is that we have here's another example of things that can happen from a muscular imbalance so say I have a weak right shoulder right here that makes my right shoulder drop just a little bit because my left shoulder is stronger than my right shoulder if right shoulder drops that causes a curvature of the spine when that causes this type of curvature of the spine happens it causes the left pelvic girdle to drop and tilt in that direction if it tilts in that direction that causes internal rotation of the knee if you get internal rotation of the knee that's going to cause the arch of the foot to collapse in that direction where do you think this individual is going to feel pain they're going to feel pain right here in the foot in the medial aspect the inside aspect of the foot you as a practitioner is your job is to responsible that's where you're feeling pain you have to identify where's it coming from and believe it or not it may be coming from all the way up here in the opposite side of the body at the top of the body and the shoulder so you've got to understand how the muscles work and how it can change our anatomy and cause pain in different places last thing that we're going to talk about is balance balance is such an intricate and complex system uh that we take advantage of every day so balance relies on a very highly dependent feedback system so you've got feedback coming from your visual so from your eyes from somatic somat sensory from all those proprioceptors we've talked about in the neural PowerPoint and from from vestibular being within your inner ear all of this information is sent back to your central nervous system it's integrated and we create an output to be able to maintain our postural control the with balance is so intricate on all the input that's coming back if we just focus solely on vestibular system if you go back and look at all the different planes of movement that we have so you have planes of movement and it's hard to draw this in a two-dimensional here but we can move left to right we can move forward and back or we can move up and down so we have our X plane our y plane and our Z plane of movement your inner ear canals if you ever look at the structure of your inner ear canals they're all orthogonal you have three and they're all orthogonal to each other and they're set up in the exact same planes as your planes of movement that's what gives us information about our spatial awareness and and the speed of our movement because as we're moving in one of those planes say I'm moving side to side the fluid within my inner ear canal is circulating it's swaying inside that plane and or inside that inner ear canal and inside your inner ear canal you have hair cells and then you have these calcium crystals that sit on top of the hair cells since the calcium C crystals weigh more and gravity is pulling them down that's what tells me I'm in an upright position right now and I'm standing still gravity is pulling down on that calcium Crystal and it's causing my hair cells to be compressed straight down so it's telling me I'm upright if my body were to go into again horrible Artistry here but if my body were to go into a Supine position and I'm laying down on my back gravity is going to pull the calcium crystals in that direction towards the ground so that's going to cause my hair cells to sway with the calcium crystals so it's pulling the hair cells back that direction and that tells me that that's my spatial orientation is I'm laying on my back laying on my side my front in prone position whatever it is so it's really interesting on how all of this works and how we can manipulate all this feedback coming to the central nervous system to know what our body is doing in space what makes you dizzy have you ever thought about that dizziness comes from conflicting information going back to your central nervous system so have you ever done the dizzy bat race you see it at baseball games softball games and stuff they may bring somebody from the crowd usually a kid and what they do is they say this is my bat right here they have them put their forehead on the bat and they spin around the bat a certain number of times and then they have to stand up and run to the Finish Line what happens is as I'm spinning say I'm spinning counterclockwise right here I'm spinning to my left counterclockwise all the fluid in my inner ear is going to spin in that direction now when I stand straight up and I open my eyes and look forward does the fluid in my inner ear just stop spinning no it's still going to circulate but my eyes are telling me I'm not spinning so now I have conflicting information going to my brain saying you're not spinning this is telling me I'm I am spinning so interesting thing I tell people is if you ever get selected to be in a dizzy bat race and you want to win it if you've been spinning counterclockwise to the left before you stand up and start to run spend one time in the opposite direction back to the right and what that does is it counteracts the fluid in your inner ears it stops it from spinning so now when I stand up and I look my eyes say I'm not spinning the fluid in my inner ear says I'm not spinning somata sensory says I'm not spinning so there's no dizziness that's going to happen there so we can train things within the body to get a certain outcome that we look for but our overall goal is to maintain postural control which is made up of postural orientation and postural equilibrium so orientation is just knowing where you are in space with with respect to your support surface so the ground that you're standing on the environment and your internal senses equilibrium a postural equili is how do we interpret all the feedback coming back to our central nervous system so that we can create a response to stabilize our Center of mass within our base of support and maintain our balance here so this is what it looks like when we're talking about postural control and base of support So this box right here is our base of support we write that out base of support what does that mean I should have if I could write better if I were to stand right here with my feet shoulder width apart and I'd take a chalk a piece of chalk and I draw a box around my feet that's my base of support there and what I have to do is I have to keep my center of mass within my base of support So coom Center of mass has to stay within my base of support if coom sways outside my base that's when I lose my balance so think of it kind of like a pendulum if I were to take a string so let's just I'm using the pen for all my examples here if this is a piece of string and I attach a weight to it down here and I hold it right here at my belly button and I stand up in the upright position where is that weight going to fall if the string were to travel all the way down to the ground we would see that the weight my center of mass would fall between my feet right around the balls of my feet and split the distance between my right and my left foot if I lean forward though what happens to it the weight because of gravity is going to start pull it's going to start pulling in that direction if I lean backwards my center of mass the weight is going to pull that direction to this direction and to that direction so when that weight when that Center of mass sways outside my toes and my heels and my base of support that's when I lose my balance so we have strategies to try and improve that and protect ourselves from losing our balance the first one here is reactive so reactive is when I respond to something that's already happening an example of this is slipping on a wet floor so foot slips out from under Center of mass sways outside the base of support here so reactive is I'm going to try and contract all of these muscles to be able to bring my center of mass back up so that Falls within my base of support there then we have predictive so predictive is when I know that something is probably going to disturb or perturb my balance and my postural control so I'm going to go ahead and try and plan for that so that it doesn't cause me to sway my center of mass out of my base of support here's an example of that right here if you've ever been on an inner city transit system a bus or a tram or a rail way uh or anything like that you know that as soon as that tram starts to move let's say it's going to go that direction my center of mass because of that direction this individual right here spine coming down Center of mass being down here around the abdomen his body weight is going to go in that direction so Center of mass is going to go in the opposite direction so what do I do I reach up I grab something to add as a a stabilizer so that when that does move I don't sway my center of mass outside my base of support and lose my balance and then the last one strategy to try and uh control postural control is proactive proactive very simply put is I look at something and I know that that's going to disturb if I were to trip on it it would disturb my postural control so I'm just going to avoid it Al together so here's an example of proactive situations you know that if you step right here or you step in here and it's slick or you step on something like that then there's a chance that that could roll your ankle or you could slip right here and that will disturb your postural control so me I'm just going to avoid it and I'm going to go around all of that and be proactive my kids not so much they're probably going to try and jump over all of this stuff and lose their postural control when they do it what happens you you do lose postural control you can regain postural control based on different uh mechanisms the first one here is the fix support which is made up of the ankle strategy and the hip strategy so think of my ankles as an inverted pendulum so these are my ankles down here uh attached to my foot and this is my other ankle and my foot here and what they do is if I'm on a solid surface so I'm standing right now on a concrete floor I'm on a solid surface and I've got a good base underneath me and something just lightly bumps me and kind of disturbs my postural control I can rely on my ankle strategy because what they do is they allow me to be able to sway back and forth like an inverted pendulum here and that can help me if I'm pushed say I'm perturbed in this direction I can contract the muscles over here to bring my center of mass back up so it's an inverted pendulum that allows me to sway here without I'm not doing anything with my hips all I'm doing is swaying around my ankles here if I get a stimulus that is too strong and I can't rely on the ankle strategy or if I'm on a surface that is non compliance something like sand or a narrow balance beam I'm not able usually not able to rely on the ankle strategy because ankles have to have a solid support underneath them so that they can Sway and create that pendulum activity so if I can't rely on the ankle strategy I have to move more proximal to my center of mass closer to my center of mass and I have to rely on the hips so then if my ankles aren't able to do the job my legs come up and attached to my torso here upper body and my arms I have to rely on my hips to move in One Direction or another to be able to bring my center of mass back within my base of support so that gravity's pulling my body weight straight down right there so this is where if you've ever seen a gymnast and they're very good highly trained at using the ankle strategy but sometimes the center of mass sways a little bit too much and you see their hips go in One Direction or the other what they're doing is they're redistributing that Center of Mass to try and sway it and swing it back in within the base of support so that they can maintain postural control on that very narrow balance beam right here that they may be standing on if none of these strategies work ankle strategy doesn't work hip strategy strategy doesn't work we have to move to our change of support mechanism so this is made up of the stepping strategy so stepping strategy basically says that if I can't regain my center of mass and bring it back within my box right here I'm going to have these are my feet I'm going to have to take my foot and step outside my box so now my foot is out here and that makes my base of support much larger so now I can keep my center of mass within that base of support and maintain postural control so all different things that we know about neural system and how can we change these one thing that you can do is through exercise and exercise training if you're trying to improve balance this is why you see in a lot of therapy settings and PT clinics OT stuff we work with foam boards and foam mats and and even in little sand pits and stuff because training in that way will advance your neural mechanisms to be able to keep your center of mass and rely on these strategies right here to keep that Center of mass within your base of support and maintain postural control now what a qu interesting question is why do older individuals fall so often or not necessarily so often but why do they fall more than younger individuals reason for that is a couple of things happen as you get older we become less active in generals and when you become less active you have a decrease in the recruitment of your type to X fibers think about if Grandma's walking down the sidewalk and she steps on something that causes her to lose her postural control what muscle fiber do you want to rely on to try and fire to bring your postural or your center of mass back in and maintain postural control I want to rely on that type 2x fiber if I haven't been active for a while I've lost the recruitment of that type 2x fiber my response to losing my balance is going to be slower and other words reaction time is slower the other thing is these are the ones that produce the quick powerful uh contractions so if I got to rely on the type one muscle fiber to bring me back up and maintain my postural control it's just going to be a slower reaction altoe as you get older other things come into play go back to this right here and the whole inner ear thing what happens to body fluid we lose some of the inner ear fluid uh inside your ear so we lose a little bit of that vestibular feedback calcium uh content goes down in the body those autol lithic organs what this is I forgot to mention that earlier but this is auto if I can spell it right autol lithic organs is when you're combining that calcium Crystal and that inner hair cells there that makes up your aoth organs so your otolithic organs don't work as good because you have calcification of the calcium crystals there's less fluid in here swaying the hair cells back and forth but on the flip side and the good side of all of this is how can what benefit is exercise so let's go here what benefit does exercise do um as you get older with exercise I maintain fluid inside the body which helps me with these inner ear canals this is what I was talking about earlier that they're orthogonal to each other so you'll notice that they're all in right angles to one another which is the same thing as our Lanes of movement right here but we maintain the fluid in here to help with the circulation of this fluid for our spatial awareness we maintain calcium content for these inner ear canals don't know why that happened for these inner ear canals and for our uh aith organs and then by maintaining exercise through the lifespan we also keep the recruitment of our type 2 x fibers so physical activity throughout lifespan can drastically improve balance and coordination and postural control as you get older so that gets us all the way through unit two we've covered unit one with bioenergetics we've covered unit two with skeletal muscle tissue and neural responses so I hope that you take all of this information you put it into use into things that maybe you do on an everyday basis but as you go through this information and navigate all of these physiological Concepts please take notes and write your questions down at any point in time send me those questions or post them on canvas so that I can answer them um in the best way as possible and maybe that answer especially from a canvas in the discussion section will help others study as we move towards the exam so make sure that you're staying on top of the material and with your group presentations those are designed to help you kind of talk about the information and give you a better understanding of it because in my opinion the best way to study all this stuff is to get to a point where you can openly talk about it if you can't talk about it if I were to ask you a question and you're not able to verbally answer the question that means that you haven't stored the information in a way that allows you to recall it and that's going to have an effect when you go to take the exam so get prepared for the exam it's going to be challenging but I know that you can make it through there and be successful in this course you just got to make sure you stay on top of it so let me know if you have any questions either by email through the canvas page or whatever mechanism you can to be able to get a clarification on the information that's needed