The Physiology and Psychology of Maintaining Balance - April 15, 2026

All right, I think we can go ahead and get started. Um, welcome everyone to today's master class in health, the physiology and psychology of maintaining balance. A huge shout out to our wonderful Spanish translation team for being here today from University Gualara. And thank you to Dr. Daniel Peterson, associate professor of the college of health solutions for your presentation. With that, I will turn it over to you uh to take it away. Okay, very nice. Can you see my screen? All right. >> Yep, it looks great. >> Wonderful. >> Okay. Uh, so thanks everybody for joining. Uh, I'm excited to talk about this. This is a topic that's near and dear to my heart. Um, I'm I'm a, as noted, an associate professor here at Arizona State University and I've been here for about 10 years. uh and most of my training um actually is in areas of balance and mobility and how our uh different parts of our brain contribute to balance mobility, how we can improve balance mobility. Um so I do a lot of research in um individuals with neurological conditions like Parkinson's disease. We'll talk a little bit about that today. Um so so it's like I said, it's it's something that I that I have a lot of interest to and I think some some experience as well. I'll note too, apologies. Um, I'm on the back end of a a c of a cold, so if I have a little bit of a cough, I'll I'll try to mute my audio before coughing loud into the mic. Um, but um, but just wanted to let you be aware of that as well. Uh, for today's talk, I've kind of separated it into three parts. So, first I want to talk a little bit, as the title suggested, about the physiology of balanced mobility, kind of how we maintain balance. Then I want to talk a little bit about the psychological aspects specifically cognition and affect and how they can contribute to balance and mobility both in indirect and direct uh pathways. And finally I'll talk just a little bit about how um a specific neurological condition in this case Parkinson's disease can affect balance and mobility. And to start I wanted to give just a bit of a background with some some definitions. So what do I mean or what what does one mean by balance and or mobility? So, when we're talking about balance, as you can kind of see here, one definition is the one's ability to maintain um their center of mass, right? So, it's kind of the if you had to take all of your mass of your body and to put it in one spot, it's usually kind of just beneath your belly button, how can you take that center of mass and how well can you um keep it within your base of support, which if you're standing um that would be the area inclusive in between your feet, right? So, how well can we keep our um center of mass over our feet when you're doing tasks that you care about? Sometimes it's standing still. That would be static balance. Sometimes it's moving like walking, that would be dynamic balance. Um I'll also talk a little bit about this um concept or construct called mobility. Um and mobility as defined here is basically our ability to move effectively through our environment, right? And people move in a lot of different ways. Some people mo walk, some people might use a walker, some people might use a wheelchair, but their ability to move purposefully, freely, easily um uh through their environment is mobility. And as it notes here, mobility typically uses a few different um uh systems, and we'll talk about those. That includes, but it's not limited to muscle strength, range of motion, and coordination of our muscles, which is facilitated by our neuromuscular system. And I want to note that, you know, balance is really hard. You know, it's something that many of us who are, let's say, you know, neurotypical adults, um, we kind of take for granted, right? We can stand and walk usually pretty easy, um, if we don't have any like neurological conditions. Um, but it's a really tricky, we'll call it like a computational problem. And one of the reasons for that is, you know, when we're standing on kind of the bottom left here, one of the ways that um our standing balance is modeled is what's called an inverted pendulum. So I mentioned before, if you have your center of mass is kind of somewhere here in your belly button. And our base of support that is our feet is relatively small. So, it's a little bit standing is a little bit like if you can imagine if you've ever um held a a broomstick and where the this the sweeping part is up above you and you're kind of trying to balance it by holding um the the other end in your hand, right? So, you're kind of moving the the bottom left and right very quickly to make sure you're balancing it. Um we are a little bit like that system inverted pendulum where the the the weight is up very high and we have a very relatively small base of support. So, it's a tricky problem. Um and it becomes even that's when we're standing that problem becomes even trickier when we walk right because when we walk our center of mass moves left to right and up and down and our base of support that is our feet the things that keep us upright that's moving as well. So we're taking steps left and right. Our center of mass is moving all over the place. So like I said it's it's a really difficult problem. And I think one of the ways that that's illustrated really well is that you know uh it took it was I think kind of in the um n late 90s early 2000s where roboticists were able to develop a robot that could walk effectively right so that was like in the early 2000s maybe depend and and now obviously we have robots that do a pretty good job of that but even some of the more more sophisticated robots now that are walking on two feet don't always do a great job. you sometimes see videos of them falling over pretty frequently when they try to do tasks like skipping or walking. Um, and so you know that we put a person on the moon right in like 1969 and it took an extra 30 to 50 years before we could build a robot that could walk effectively. And I think that really illustrates how difficult of a computational problem this is. Now, we do it most, like I said, neurotypical young or or middle-aged adults do it pretty easily, but that's not because it isn't e that's that's not because it's easy. It's because our neurological and muscularkeeletal systems are so well tuned to do this task. And our system is our body is very well tuned to do this task because uh it's such an important one. And you know, evolution has um facilitated our ability to do this task very well. Okay, so that's my pitch of kind of a background. what are we even talking about here and why is it important and and again a pitch of how how kind of a difficult um uh problem it is to solve neurohysiologically. Now I want to talk a little bit about how we solve that problem right what is how do we use our physiology and our different systems to facilitate uh balance mobility and when I think about our movement and our balance mobility I think of it as like this cycle right so um we select a movement right um our brain selects a movement our body carries out that movement then we sense our surroundings to see how well we're doing at that movement we excuse me. And then we integrate that that sensory information to update the movements and either keep going, adjust it, make it different, make it, you know, whatever um to then continue uh moving, doing doing that thing in in an effective way. And so we're going to talk about each piece of this cycle and kind of how our different systems contribute to them. So the first thing I want to talk about is the way we move. Um and our movements obviously are or I should say the aectors the parts of our body that carry out our movements is our muscularkeeletal system. Right? So we have muscles throughout our body and those are connected to our bones through tendons and li and the ligaments obviously keep the bones connected and so that muscularkeeletal system is the thing that facilitates movement. uh and as you're probably aware uh you know those the pieces of that muscularkeeletal system the muscular system uh you know are critical to to movement obviously and they can uh change with time right so uh when in older adults uh you will sometimes get changes in the efficiency of muscle the composition of muscles um that changes muscle power and muscle strength also our uh skeletal system can change with age right So that can affect things like your stiffness, your range of motion. In some cases, there can be mechanical blocks at joints. Things like arthritis can reduce the the range of motion or the flexibility. Sometimes there can be pain with movement. And so on the on the right, you can see a figure of maybe a neurotypical middle-aged adult um standing. And then with age, you might see some adjustments to the uh kind of posture of those individuals. Sometimes you get a little bit more knee flexion, a little bit more what's called lordosis of the lower back. That's a um kind of forward bend um such that the the stomach sticks out and a little kyphosis of the neck's uh neck here. So anyway, these biomechanical changes due to changes in our muscularkeeletal system can and do have um uh influence on our uh on our ability to balance and maintain mobility. All right. So we have our muscular skeletal system that carries out this movement. It facilitates standing, walking, etc. Now I want to talk a little bit about you know let's say you start to walk. You start to make a movement. Um and then of course we use our senses to see how or to observe I should say how we're doing at that movement. So let's talk about the senses that we use to observe how our balance is going. And there's really three key senses, three systems that we use to uh understand our balance. And one is vision. The next is what's called propriception or smata sensation. We'll talk about that. And the third is our vestibular system or vestibular function. And these are three different systems. Your visual system, your smata sensation and propriception system and our vestibular system. And they all contribute to balance. So we'll talk about each one in turn. First we'll talk about vision. This is something that I mean I'm sure all of you are aware of. And vision of course senses where we are and really where our head is in relation to other objects, right? Where are we with respect to um the walls of the building we are in or you know your surroundings uh your environment. Is something moving towards you that you need to avoid or not? Right? And so vision is obviously very very important. Um, and it's particularly important for things like balance because, you know, your your brain can make some assumptions. So, if you're sitting inside a room, let's say, your brain makes some assumptions that the walls of the place that you're in or the the desk that you're behind or whatever, you make the assumption that those are static. That is, those are not moving. So, if you see them moving towards you, it's unlikely that the walls are moving. It's more likely that you're leaning forward. or if the wall looks to be moving away from you, it's more likely that your body is leaning back. And so that gives us information, our visual information or our visual system gives us information about um really if you make the assumption that your surrounding your surroundings are static, it gives you information about how we're swaying. Are we still? Are we listening to the left, right, forward, backward, are we walking when we're walking? How fast are we walking? And so on and so forth. Right? So vision is very important to facilitate uh mobility and and balance. And I will say that there's been a lot of research recently indicating that visual information um and and visual function is quite related to a person's fall risk for the reasons mentioned. And of course um with age there can be a lot of changes in visual function right? So things like acuity that's um how clear you can see things contrast sensitivity understand seeing um uh distinguishing light and dark peripheral vision depth perception all of these can contribute to for example your ability to avoid obstacles and step over you know cracks in the in the sidewalk or roots if you're outside or whatever it is. Um, and of course that can have an important um, influence on whether or not you trip or slip or fall and potentially injure yourself. The next system that I want to talk about that contributes heavily to balance is it's really called the somato sensation system. And if you break that word down, somato means body and then sensation is sense, right? So it's your body sense system. And there's kind of two pieces to the somata sensation system. One is proprioception. Okay? And the other is cutaneous. Proprioception is the signals typically from your muscles but in some cases from your some sensors in your joints. And propriception tells us where our body is in relation to itself. What I mean by that is if I if I'm standing here and my arm is at about 90 degrees. So let's say my forearm is about 90 degrees to my bicep. If I close my eyes or I kind of look away, I know that my arm is about 90 degrees. And I know that even though I can't see it. And the way that I know that is through our proprioceptive system. And the way the propriceptive system works is we have lots of little sensors inside our muscles that track how stretched each of our muscles are. And since my bicep muscle is connected to my forearm, the more I extend my forearm, the longer this bicep gets. And the more I uh bring this forearm in, the shorter the bicep is. So there's little sensors that that that understand how long the bicep is. And based on how long the bicep is, it tells me about what angle my for my about the angle between my forearm and my um upper arm. Right? And of course, we have muscles that cross literally every one of our joints, right? So if you take all of that information together, you get a sense of where your body is with respect to itself, right? Where my wrist is with respect to my forearm, where my forearm is with respect to my bicep, bicep to trunk, right? Trunk to pelvis, pelvis, etc., etc., etc. So that's propriception right and again it comes from our muscularkeeletal system and tells us where we are with respect to itself and then our cutaneous sensation that is the senses that we have in our skin right so all the little sensors that help us feel that's touch it's vibration it's fine touch right so for example when you're standing your the the the skin underneath your foot tells you where you know which part of your foot is touching the ground is there more force at the front of your foot, is it in the back of your foot? And that helps us maintain balance while we're standing. So this this sense together smata sensation which is propriception where we are with respect to ourel and cutaneous so for example if we're touching the ground or some some part of us is touching the ground that tells us how we're touching the ground. All of that together as you might imagine is very important for maintaining upright balance. And of course, as you might imagine, you can have changes in somatoensory function that could impact balance. For example, if you have um uh what's called peripheral neuropathy, peripheral neuropathy is where you have difficulty sensing at your extremity. So, for example, your feet may not feel the ground very well, and then you don't know whether you're leaning forward or back, right? So inability to sense your position could be uh is a loss of function in our smat sensory system which can increase risk of falls. Similarly um you might have difficulty sending signals throughout the body. So for example in people with multiple sclerosis um their muscles are largely okay but the um the axons of those muscles which are essentially like the wires that carry information from the muscle up to the brain and from the brain back to the muscle those can be damaged. So even though their propriceptive sense could be okay, um the speed and effectiveness that those muscles travel to and from the brain can be altered and that can also affect our ability to uh maintain balance. The third system that I want to discuss that provides lots of relevant information about our um about balance is our vestibular vestibular system. The vestibular system is pro is supported primarily by the vestibular apparatus and that's this little guy here. It's this purple apparatus and it's embedded in the bones near your ear. So it's embedded in your skull right inside of your ear. And we actually have two of these. So you can see this is a top down view and there's one here on the left and there's one on the right. And these vestibular vestibular apparatuses or vestibular apparati you will um they're very very important to for for balance. Um the the thing that they measure they kind of measure two things. One they tell you what your what your head is doing with respect to gravity. Okay. So for example, if gravity is pulling straight down, right, and I turn my head to the left, my vestibular system says your head is tilted about, let's say, 30° with respect to gravity, right? It gives me and my brain that information. The vestibular system in in addition to that, it also gives us information about acceleration of our head. if we accelerate forward or decelerate either in a linear way or in a rotational way, it'll give you information about that. So, for example, if you've ever been sitting in the backseat of the car and maybe it's in the evening or you have your eyes closed and uh the car accelerates and you can feel yourself kind of move, you can you can feel that acceleration. Even if your eyes are closed, you can't see the you know what's going on outside of the car, you can feel yourself accelerating. that information is coming from your vestibular system. It's giving you that information. You're accelerating forward, you're decelerating, you're turning. You can usually feel those turns as well. Um, if you're moving somewhat quickly, you can feel that. And again, that's coming from your vestibular system. So, this, as you might imagine, is critical for assessing balance and posture. It helps us know if we're vertical, if we're leaning left and right, how we're moving, how our head is moving in space and all that is really central to make sure that we are um again we understand where we are, how we're moving and whether we're upright. So again, if we have to give it just one sense or one um kind of description of sense, it is sensing our body in relation to gravity. Good. All right. So we talked about our three primary senses. Vision with which measures our where we are with respect to our surroundings. Somata sensation and propriception which measures which measures where we are with respect to our self right where how one part of our body where it is with respect to the other part of the body and then we looked at our vestibular system and would that mentions or that gives us information about where we are with respect to gravity. And so the last thing I want to talk about here is now that we you know we we take some steps right we see how it's going right we use all of these systems these sensory systems to understand are we moving the way we expected to move are we moving faster slower etc. The last thing that's very important is we it's not it's not only or it is not sufficient to just sense these um movements. We then have to take those movements and integrate them to make sure we are moving the right way. We have to actually not just sense our surroundings but perceive and understand our surroundings. And that happens through an integration process in our brain. So let's talk a little bit about more uh more about what that is and what it what it looks like. When I say sensory integration, um, what I mean is, you know, whenever you're, let's say you're standing or walking through a well-lit room or you're outside and and it's a comfortable, um, you're walking on a a firm ground, right? We might be using our different systems, our visual system, our vestibular system, and our proprioceptive system pretty equally, right? where you're all of those are giving us very good information about our surroundings and our body, right? And so that's good information. So our brain's taking all that in and and having a really good accurate representation of what we're doing, how we're moving, and how we're maintaining balance. But now let's say if you're walking for some reason, you close your eyes, right? And you continue walking, but your eyes are closed. Well, in that case, you know, your the the your eyeball is still sending s signals. It's still firing. It's still sending information to your brain. But your brain has to then disregard that because it's not providing any meaningful information. Your eyes are closed. You can't actually see your surroundings. So then you have to very quickly just attend to your somataensory system. That's your your lower leg or your your legs for example and your muscles and your muscularkeeletal system and your vestibular system. Right? Okay, so you have to very quickly downregulate or downweight the visual components and upweight these other two components. Now let's say you continue walking. Now you open your eyes again and you move from a very firm surface to a soft squishy surface. Maybe you start walking on sand or you are walking on pebbles that are moving under your feet. Well, in that case now our muscularkeeletal system, our propriceptive system is not giving us very good information. So there maybe you have to downweight your propriceptive um contribution and really upweight let's say your visual system, right? Um, so what I what I mean to um uh um discuss here really really what I really want to um say is that all the time as we're moving through our environment we're always um dynamically changing how we attend to our those three different systems vision vestibular and propriception right and this process of integrating this information in an effective way has to happen really quickly right you have to very quickly go from paying attention patention to the information to your eyes to not to paying attention a lot again right and attending to the propriceptive information or not etc. And by the way, this process is called sensory reweing. Right? Here we have an equal waiting. Now we have an unequal waiting where it's 50/50 across two of the three. Now you have another uh set of unequal reweing. And again, our ability to very quickly rewe how our brain attends to these different um systems is key to make sure we're maintaining effective balance. So what this really kind of looks like if we have a schematic that brings all this information together when you go to make a movement right so any motor output in this case the motor output is walking or balance upright um stance etc you have to have um you know that the individual sensors the sensor that's in your ear that is the vestibular apparatus the sensors that in your muscles they're called muscle spindles but they they help us understand uh or provide semataensory input and your your visual sensors that is your eyes need to be working properly right so this the the things at your periphery that actually sense the world need to be working properly and then all of them send information into your brain and now your sensory integration centers in your brain those parts of your brain need to be working properly too so they can effectively weight and rewe that sensory information together so that we select the right motor output. The only other thing I want to and that's all true. The only thing I want to kind of add to that, a small additional layer that I want to mention is that we don't just we we're not moving only based on our surroundings. The other thing our brain always takes into account is our prior experience, right? So, you know, maybe if you live somewhere that's cold and you know, you you you you walk in areas where there's ice on the ground this time of year, right? If you've never walked on ice before, you don't really have um a prior experience there. But if you've slipped on ice one time and you walk up to that, you know, that that's that that patch of ice again or area that might be icy, that prior experience comes into play and that will also influence this the motor selection that you u choose, right? So you so it's it's I guess I I mention this to because your brain um to to underscore the fact that your brain is doing a huge amount of computational um uh work to both sense all of the things that are happening, right? Can you is it is it a well-lit room? Can you feel the ground well with your feet? Um are you upright? By the way, what what is your what do your surroundings look like? Have you been in this place before? Was it slippery? Are there handlebars to grab onto if you lose your balance? All of that comes in and then your brain makes a selection on how to move forward. I'd like I'm going to take a step. It's going to be a medium-sized step and um you know, I'll put my hand out to make sure I grab a handrail just in case I lose my balance. So, that's an enormous amount of computation that's happening and it's all happening basically under under the hood, right? So for again those folks that are neurotypical adults um you know kind of middle-aged let's say or younger um all that happens without even really thinking about it but it but it just because we don't think about it doesn't mean there it doesn't uh take a lot of computational power um and like I said that can change with older adults right or people with neurological conditions um such that um doing all of these tasks can be a little bit trickier and or um they can do them but it might they might not do them quite as effectively um that could increase their risk of falls. Good. So, I'll summarize this together. Right. So, we talked about the fact that movements occur. Um, we sense our environments. Um, then we uh you take all those senses together. We integrate them. That can um help us to understand the next motor selection if we need to make an adaptation of that motor selection. And then we continue that movement along. So, now I want to switch gears a little bit and talk about and that's the longest section by far. Um the next two will be much shorter but I do want to talk a little bit about the psychological contributions to balance and mobility. And there's two here we're going to talk about. I'll introduce them very briefly here and then we'll talk into a little bit more detail. But one is cognition, right? So cognition is our ability to um so it's executive function, our ability to attend to multiple things in our environment. Um how can we attend to mult multiple sensory inputs? How do we quickly assess our surroundings? And then I want to mention we'll talk a little bit about something called affect. Affect is a little bit different from cognition. It's that's more related to things like concern, anxiety, fear, and emotion. So let's talk first about cognition. And I'll say to you that both of these can have both direct and indirect effects on balance. And we'll discuss both of those. So these are kind of some kind of silly gifts about people, you know, if they're distracted. Most of these people are distracted because they're talking on their phone and you know person falls into a uh into a pond or bumps into a wall or a door or whatever. And you know I I show these they're kind of silly in this case and everyone's fine. Uh but when you're distracted from the task at hand walking uh it can cause you know a negative let's say outcome right bumping into someone or something. And of course with older adults or people with neurological conditions when you are distracted in this way uh and you slip and fall like this that can actually have kind of a pretty negative outcome. And one of the ways that we can think about how distraction influences movement is we usually think about our attention as kind of a pie, right? So you have let's say here's our total available attention, right? 100% a full pie. And let's say you have some sort of motor task. Maybe it's a walking task, but it's pretty straightforward. And that uses something like, I don't know, 35 40% of your um attention. And then you add a cognitive task. Maybe it's talking um holding the phone to your head and and you're you're talking to a friend. But you can put both of those together. And we still have a little bit of our pie left, right? So you can do both of those tasks pretty effectively without a lot of decrement in performance. However, and you can probably see where this is going. If you make it a more difficult motor task, let's say now you're um walking like on pebbles or something that are moving and you have a more difficult cognitive task. So instead of talking to a friend on a phone, rather you're texting or something like that, then that's more that's more pie than we have to give, right? That we don't have enough attention to accommodate both of those tasks. And in that circumstance, there will be a decrement in performance in one or both of these tasks, the motor task or the cognitive task or maybe both. And when you have that decrement, that's called a dual task cost or a dual task interference. And ultimately what this looks like is uh like I said, you get worse at one of those tasks or you just don't really pay attention to the gate task and then you bump into something or you fall over. Uh and by the way I will also note that in some cases like with aging or with neurological conditions the pi actually gets smaller. The total amount of attention that we have gets smaller. So that means that there might be for the same two tasks. If you have a younger adult do two tasks and an older adult do two tasks there probably more interference uh less ability to do those tasks together in the older adult than the younger adults. Um now I want to turn our attention to um affect and this is the idea of fear or concern of falling and as I mentioned before uh fear and concern of falling can have both direct and indirect effects on our uh mobility. Okay. some of the indirect or an indirect route through which a fear of falling can impact our mobility is because sometimes if if let's say someone experiences a fall let's say you have a whatever 65year-old adult and they experience a fall and sometimes that could cause this fear of falling or concern of falls wow I maybe they didn't even get hurt right well they didn't get hurt which is great but man that was really scary and um that can sometimes uh result in decreased physical activity. They might think, well, I was going to go for a walk around the block this afternoon, but man, I'm really nervous about having another spill. I could have gotten hurt. Um I don't want people to see me fall over, so maybe I'm not going to go for that walk, right? And if that happens over time, that can result in, you know, we all we all know how important physical uh exercise and physical activity is for mental and physical health. So you might have further muscularkeeletal decrements that can result in more gate instability increased further increased risk of falls maybe you have another fall that results in even more fear of falling and you can kind of see how this negative cycle can continue u and that's driven in part by this fear or concern of falling and the other thing I'll mention is a lot of times people talk about rightly the fact that decreased physical activity can um result in uh uh you know muscular skeletal decrements. So physical decrements but also decreased physical activity can reduce our participation in our uh for our life right and we talk about participation sometimes that means like you know interacting with our family or our friends etc. And so, you know, it's not just that if you don't if you have concerns of falling, you maybe you don't um you know, you don't go for a walk and exercise, but maybe you decide not to go to a concert with your friends or maybe you decide not to, you know, go visit your your family or something like that. And of course, that can lead to another negative psychological output outcome of social isolation and depression. So, really, when you're thinking about treatment of concern of falling, it's really really important to think about these affective conditions. um because they also contribute to overall quality of life uh in a really important way. The other thing I'll mention just briefly is that a fear of concern of falling can affect your mobility in an indirect way as we just mentioned, but it also can even affect it in a direct way. So people that have higher concerns of falling can have more variable steps, stiffer steps, and less efficient walking. There was an interesting study from a colleague of mine, Toby Elmer, that showed that when they people are walking, they track the accuracy of their steps um when they come up to some barrier. And basically what they showed is people who had low fear of falling had pretty accurate steps. Whereas those folks who had very high fear of falling had less accurate steps. They had more foot placement errors suggesting that when people are have ner are nervous about falling, they're less accurate with their feet. and that could actually increase the risk of falls. Okay, so quick summary here. Um, you know, we've talked a lot about uh the this kind of psychological or affective and cognitive components of falls. And this is a figure from a um um a paper in Parkinson's disease, but it's true also for healthy older adults where if you have a fall, that can result in injuries, but also fear of falling that can result in immobilization and reduced participation. that can result in more things like muscle weakness, social isolation, that can result in more postural instability, more falls and again you have this kind of negative cycle um that's really important to address if not break um to make sure people are you know um u integrating with their lives effectively and participating and having a high quality of life. All right, the very last section and this will be the brief mo most brief, but I want to talk very briefly about the effects of disease on mobility. And we'll start by kind of discussing just briefly what parts of the brain contribute to mobility and gate or walking. And the there's some acronyms here, but you know, there's a lot of different parts of the brain that contribute to walking. There's a so-called locomotive brain network that includes some areas of the cortex up in the top of the brain. Uh areas deep in the brain in the basil ganglia like the stryatum and globus paladus. There's areas in the brain stem like the MLR or mephalic locomot region. It's the mouth and then areas within the cerebellum called the cerebellar locomot region and others. Anyway, you don't it's not critical to know all the details, but you know, this is a pathway that contributes heavily to gate. And if we look for example in Parkinson's disease, this is a schematic showing where some of the deficits in Parkinson's disease typically happen, where some of the neuropathology often happens. And what we see is you know even if you just kind of squinch your eyes you can see that many of the same areas that are influenced in Parkinson's disease areas where there is neuropathology in Parkinson's disease are the same areas that we rely on to facilitate gate and balance and walking right so there's cerebellar regions there's brain stem um deep brain regions and cortical regions so unsurprisingly if you take a person you know a neurotypical adult and then they begin to have Parkinson's disease you might see deficits in each of these these regions and that can have a number of uh behavioral manifestations. They can affect gate in a few ways. So here are a few of those and we'll talk about each of them briefly. When you have changes to the cortex that can influence a few things that can result in more variable and more asymmetric steps. It can also change your cognition and attentional control. So it can change it can change like that pi of attention might get a bit smaller. When we have changes in our deep brain structures in our basil ganglia that can result in smaller movements right so the steps people take might get a bit smaller uh and sometimes more narrow in a way that can be problematic. When we have changes in our brain stem that can affect our stability. So even just standing or moving might be more unstable. And in the cerebella region that can affect how automatic our walking is. We might have a reduced ability to walk automatically. So we have to think even more about that gate. And finally all of this together can um change uh our depression right it can a lot of people with Parkinson's disease both because of the disease but also because of the neurohysiology of the disease u might have different levels of uh concern and depression uh and that can result in activity um reduction and therefore again this kind of additional negative cycle. So again, there's a number this kind of influence or illustrates the number of ways that changes in the brain that can happen in Parkinson disease might also influence behavior. But I will say that's kind of the bad news. The good news is um our brains even in you know conditions like Parkinson's disease or older adults, our brain retains the ability for learning and plasticity. So that can look a lot of different ways, but the way that I'm most familiar with and actually one of the typical ways in the field is through rehabilitation. Rehabilitation can improve uh ability and mobility and ultimately quality of life, right? So you can have physical rehabilitation that would be like working with a physical therapist or a physiootherapist, right? So you can change your muscular skeletal system and your movement patterns. You can work with an occupational therapist um to understand one's home environment or their working environment or how they complete their activities of daily living. You can work with a speech language pathologist or others um to think about cognitive rehabilitation, how well you can utilize and uh shift your attention. And then of course, ideally, if there's the resources, which there isn't always, but ideally you might have some combined therapy, right? So understand all of these different uh rehabilitative approaches in context um to make sure the person can be living their best life despite some of the um neurological conditions that they might be faced with. Very good. So just to summarize all everything we talked about, right? So we talked quite a bit about how mobility relies on a distributed network of systems, our muscularkeeletal system, our sensory systems, our nervous systems, and that all works together to make sure we're moving effectively. Um, our mobility relies on all both our physical and psychological abilities including affect and cognition. We talked very briefly about how neuro and muscularkeeletal pathology can influence mobility, right? So for example in Parkinson's disease and then we just touched very briefly at the end on the fact that while there can be deficits that occur in for example people with Parkinson's disease rehabilitation usually um can have a positive impact on mobility and as neural substrates to facilitate improved quality of life in the face of those neurological conditions. So, with that, I'll stop uh and thank you so much again for for listening and I'll turn it back over and uh happy to answer any questions that you have. >> Thanks, professor, for that insightful presentation. Um, as we collect more questions, uh, for the Q&A, I'm going to go over a few things. Feel free to bring out your phone. Um, there are a few things to scan. First off, as always, this is a QR code for a feedback survey for today's master class. Feel free to fill it out. It's completely anonymous and only for questions. 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I will go um back to the other ones as we get more questions. All right. So, first question. If an older adult with fibromyalgia has balance issues, how can they improve their balance to prevent falls? >> Yeah, that's a great question. Um, and I will note there are a lot of different rehabilitative approaches that are available. Um they uh first of all if possible um anytime you have a neurological condition it's good to consult with your um any uh whatever allied health person you you you um work with right whether that's your physician or a nurse or a physical therapist right to really understand um your specific systems and and circumstance. But in general, things like physical therapy can be or physical rehabilitation in general, sometimes that's physical therapy, sometimes that's working with a personal trainer, can be very beneficial for balance. Um, one of the things that's really important when in kind of the first evaluation is to understand what the rate limiters are for that individual. Right? Some people their balance is impeded because they don't have enough strength. Some people their balance is limited because they uh don't have the coordination of the muscles. Sometimes it's a range of motion, right? So what the thing that will help each person uh will probably be different based on that person, right? So that's kind of one of the first things that a that a good physiootherapist will do is really assess that individual, see what is limiting their balance because that's very different across each individual and then they'll try to start to train that that person. Right? So in general the training would look like depending on the the deficits that are observed it might look like again strength training uh balancing that's maybe like standing on one leg with eyes open or eyes closed it could be working on range of motion right so I guess that's uh maybe not the most satisfying answer but it the the part of the answer is it depends on the person and the person's deficits that they're that's that's causing their change of balance. Um, and if one's not sure, you know, they could go do some regular things. Always safely exercising is like the baseline best thing that anybody can do and having good nutrition to the best that they're able, right? So, those are like the good the things that are good across the board. And then if you're specifically trying to focus on balance, again, um trying to interact with a healthcare professional is always a great call. Um, but you know, if you could um do some balance exercises like standing with eyes open or eyes closed, sometimes standing on a foam mat, um, as long as you can do those things safely, if you're doing them by yourself, that's really key because you don't want to accidentally have a fall or a slip that could cause an injury that could then, you know, lead to some of those negative outcomes that we discussed. >> Excellent. Thank you for that. Another question from Masha. If someone has poor smata sensations, uh, they must use more cognitive and executive function to stay upright. So, why does this make them feel more mentally exhausted at the end of the day? >> Yeah, that's a really great point. Um, and it's uh kind of maybe a little bit embedded in the question. So, I think you're you you kind of hit it on the nail on the head that when you have a change in any of your sensory systems, right? So let's say you have poor smata sensation or poor vision or poor vestibular function for whatever reason. Your brain has to work a little bit harder to integrate the information effectively. And sometimes your brain has to work a little bit harder to um understand its surroundings, right? And anytime you have to use more attention for a a task that didn't previously need that attention, right? It's using a little bit more energy, right? So if you you know let's say a healthy let's neurotypical adult they don't have to really think as much about walking but a person who has one of changes in one of these systems they have to think a lot more about walking. It's not that they have to think less about the other stuff. They still have to think about um you know what they're going to have for dinner. You know they have all the same cognitive load and then they have to think more about this thing that they didn't have to think about previously. And together that's tiring right? um our brain uses an enormous amount of energy to uh when it's doing its its the things that it does when you're thinking about stuff. Um and so it would be very very frequent um for that to lead to an extra level of fatigue at the end of the day which is something that uh is good to kind of keep in mind. So a lot of people that have um conditions that affect their sensory systems, their neurological systems, they have to be a little bit wary, not wary, but at least aware of where they are in the day and it's well usually by this time in the day I get a little bit tired, right? So, all right, maybe I'll plan a little bit less in that part of the day so I can rest a bit and then recharge the batteries and then go back out to participate and go to class or, you know, be with my friends or go back to work or whatever it is um that they need to do to, you know, again have that high level of participation which usually is really beneficial and leads to a higher quality of life uh in most folks. >> Excellent. Thank you for that. Another question from Norberto from USA in Honduras. Um, so they they've looked into it and they've seen studies that say strength training or weightlifting is better than purely cardiovascular exercise like jogging. Um, he wants to get your opinion. What do you think is better? Uh, or should you combine a bit of both types of exercises? >> Yeah, that's a that's a great question. And I will say this, so this depends a lot on um who you're talking to. And I will admit I'm not a an expert on like the physiology of strength or exercise training. I'm more kind of focused on the nervous system. You may have had other speakers in the past or have some in the future that have really a lot of expertise on that in particular. But when you're talking about, let's say, older adults or folks that have some neurological conditions, um, usually there can sometimes be subtle differences in the effectiveness of different interventions. For example, you know, some people will do all these head-to-head clinical trials to say, okay, for people with Parkinson's disease, which is better, um, dancing or tre or walking on a treadmill or boxing or taichi or strength training or whatever? And the answer is there are sometimes some subtle differences, right? So, some studies have found that boxing is particularly good. Um, and there's some really great boxing groups. I'm in Phoenix, there's some really great uh boxing Parkinson's groups. It's really fun and cool. Um, sometimes people find dance can be very good, right? But the thing is, at least for people, let's say with people with Parkinson's disease, there might be some subtle differences, but all of those are so much better than doing nothing that usually the thing that we say is do the thing that you like to do, right? Do you like dancing? Dance. Do you like boxing? Go box. Do you like walking around your neighborhood? Do that. Do you like strength training? Do that. Do you like to have a combination? Do that. Because it's different. Because again, if you don't if you say if I say to everybody like look um ballroom dancing is the best way to improve balance and Parkinson's. It's really the only way to do it. Well, some people might be like I don't like I don't like ballroom dancing or I don't have a partner that I can consistently go with and so they don't just they can't do that so they do nothing. And nothing is the worst option by far. Right. So if you're gonna So I I agree with you. I agree with the comment that there can sometimes be some subtle subtly diff subtle differences in the effectiveness of different interventions cardiovascular training strength training um again you know specific um things boxing whatever all of them are so much better than nothing that again if you're talking about older adults or people with Parkinson's disease finding the thing that you like to do that you're going to stick with cycling some cases another one there's a really important uh interesting talk I just went to a couple weeks ago talking about the importance of cycling for Parkinson's disease or the the positive effect of cycling that just finding that thing that you're going to do. That's the best thing to do because as you're probably all aware, exercise is not a one-time thing you do, right? If you exercise one time, that's really not going to help. You know, exercising for the for the purposes of increasing um uh uh balance and mobility and quality of life really only is effective if you can do it long term. And you're only going to do it long term if you like it or find some joy in it. And so find the thing that you have joy in and do that thing, right? So, it's a really great point and and by the way, if you like everything, then yeah, you can do uh and we could talk later. There's some subtleties about which specific activity is best and that's another conversation, but you know, a lot of people have preferences, right? That makes sense. Um, so utilize those preferences to choose the thing that you're most likely to stick with over a long period of time. >> That's great. I like that. Another question from Emanuel. They have a question about uh if there is a gap between simplified schematic representations of brain regions uh and the actual complexity of their interactions in maintaining balance. >> Yeah. So that's that's a great point as well and um if I I maybe I didn't explicitly mention it and I probably should have um the figure that I showed of the brain is indeed a very simplified schematic showing how uh the different regions of the brain that contribute to mobility. Um, and you're absolutely right that the brain is enormously complex. Um, and we in the neuroscientific community are still um, just kind of chipping the tip of the iceberg as far as how the brain works, the things that the way that it works, the um, the way that it contributes to specific movements. Um, and so we have an enormous amount still to learn about the specific um, integration and complexity across structures. So absolutely um you know what I showed was was a simplified version. It is much much much more complex than that. Um but I do think that sometimes these simp relatively simple schematics can give an idea of the type the parts of the brain that are likely contributing to the the movements even though the specific complexity is a little bit hidden from view. Um uh so it does give us an idea of broadly speaking what parts of the brain might be contributing and when there are deficits in those parts of the brain how it might be contributing to movement but it's a it's a very valid point. I appreciate you bringing that up. >> Excellent. Thank you. Another question. How do physiological imbalances such as sleep deprivation or poor nutrition affect our emotional stability? I think you touched on this briefly. Could you go a little more in depth on that? >> Yeah. Um the short answer is yes. um in that absolutely. So we have certainly there's a lot of different way a lot of different things that impacts we'll just call it our quality of life right so if our quality of life it consists of a lot of things our emotional health our physical health our social health and there's many many things that contribute to that some things that and by the way how all of those things are weighted as they come into your brain right uh are different right some people if they have chronic pain some for some people that has an enormous negative effect on their quality of life. Some people because of their brain chemistry, it has a little bit of a less effect. Some people um have really it's really really important to get, you know, eight hours of sleep every night because if you don't get that, you're foggy and you're grumpy and you don't feel good and all these things and that can have a negative effect on how you behave and your quality of life as well. So, you're absolutely right. Um you know, I touched a little bit on cognition and affect and how those can affect mobility. Um but there are a lot of other things. Absolutely. Like nutrition and sleep are key components um that can also affect your quality of life, your cognition, how you know again if you're clearly thinking or foggy and all of that can um uh influence for example how safe it is for an older adult to you know walk down the street, right? If you're if you had a good night rest and you you know had a good meal and you're feeling good and you're feeling strong, that can lead to a very successful outing. Whereas if if one or multiple of those things are are not in place, it might be a less successful outing because they're more tired or you might trip and fall because you're distracted because you didn't get enough sleep, etc. So, I know that's it's it's a lot of kind of balls to juggle and a lot of things to keep in the air as far as understanding the overall in um our ability to maintain balance. But that's because frankly it's just a very complex uh multi-dimensional construct. um our ability to to walk and be and and and be safe. So, you're absolutely right and I appreciate you bringing it up and with 30 minutes it's hard to touch on everything, but um you're absolutely right that those are important components as well. >> Great. Thank you. Uh we probably have time for two more questions. Our next question um and this one I actually had as well. So if all the areas where our system um are is declining like so when we took a look at the Parkinson's degree we were able to map it out. Um I guess can you just get a touch base on what's happening with like finding a cure for Parkinson's disease or uh remediation? >> Yeah that's a great question as well. Um so as of right now there is no cure for Parkinson's disease. Unfortunately Parkinson's disease is a neuro degenerative disease and what that means is the brain is changing in ways that we don't know how to stop those changes. Okay. Some of the changes that are occurring is there's these proteins that um they're actually can can be normal in in a normal brain, but the proteins can kind of fold in a way that's um um uh pathological and malignant. And when they fold in that way, they can uh result in degeneration of certain brain regions. And we don't know exactly why those proteins start to fold in that way in people with Parkinson disease. Um, we do know that the the misfolding that happens and the deposition of that misfolded protein usually starts around in the brain stem in an area called the substantia And that's only important or it's it's particularly important because the substantionigra releases a neurotransmitter called dopamine. And dopamine is very important for movement and for for um psychological function, depression. And so while we don't yet have a cure for Parkinson's disease, we don't know how to stop that misfolding and um cell death, one of the most common treatments is to take a pill that replaces the dopamine that your body no longer makes or doesn't make quite as often or effectively. And that's that drug is called Levodopa. Levodopa because it's a it's a form of dopamine that gets into the brain and then it turns into dopamine. uh and essentially that that that that um pharmacological intervention is uh the most common way to help treat some of the symptoms of Parkinson's disease, but it still doesn't treat the root cause of Parkinson's disease. So there's there's an enormous amount of energy and effort both in the research community and the scientific community and the pharma and the pharma community to understand and cure Parkinson's disease. Unfortunately, we're not quite there yet. Um but but I will say that again our some of these uh uh treatments like the the pharmacological treatments can treat many of the symptoms. Um and I will also say that uh while there is no silver bullet there is some very early evidence that um physical activity safe physical activity might be a um a way to slow the progression of Parkinson's disease. So, um, eating well and and and good physical activity, um, there's some evidence that that might kind of slow that progression and slow the amount of misfolding that's occurring and therefore how quickly Parkinson's progresses progresses. Now, that's hard to do in some cases. Um, and by the way, physical activity is good for most things, right? Cardiovascular health, um, muscularkeeletal health, you know, whatever, brain health in general. Uh, so, so that's kind of one of the the few silver bullets. Um, which kind of comes back to my comment earlier of, you know, find a physical activity that you can that you enjoy, that you can do safely, um, that you can do with friends ideally because that kind of helps keep everybody accountable. Um, and if you can find that, that's a really good thing to do that can have benefits across the board. >> Excellent. Well, thank you for that. Um, I think we have time for one more. So, uh, how accurate and reliable are the mobility measurements in the health health app on iPhones? uh can it be trusted for older ex older adults to use to alert them uh when they might fall? >> So which specific app was did the person mention? >> The just like the health app that comes with your iPhone. Yep. Yeah. >> Yeah. Um that is another great question and I you know so I I don't know if I can answer this um with a high level um of of specificity. I will say um I don't use a lot of personally I don't use too many health apps for things like sleep. Um you can track things like heart rate pretty effectively. You can track things like steps pretty effectively. sleep can be a little bit tricky. Um, and so there's a lot of variability in the quality of, let's say, wristworn devices to track sleep and sleep effectiveness. Um, so I guess it won't be the most satisfying answer, but it's highly dependent on the device. Um, and even the best devices can um sometimes give a little bit erroneous information. Um, it's and it depends a lot, like I said, on what you're trying to measure. If you're trying to measure things like, you know, the approximate number of steps you've taken during the day, that, you know, that can be be pretty accurate with simple devices like a a step counter um or smartwatch or whatever. But some of the other sleepreated things can be a little bit trickier. Um and um uh but things like sleep can also be really important. So yeah, I don't know if I have a good answer to that one. I guess other than it depends on the device and without getting into all the details of it, um it could be a little bit tricky to to answer effectively. So yeah, apologies on that one. Um, but uh, yeah, it's it's it's it's an important question. It's just not one that I have a great answer for. >> No, you're all good. And that was great. And thank you so much for your time, professor. We really appreciate it. And thank you everybody who was able to join us today. I hope to see you guys in our next master class on the 22nd of April, uh, the media power of sports. But thank you. I hope you have a great rest of your day. Bye everyone.