Hi everyone this is Professor Gunnall. Today's lecture will focus on chapter 1 the physiology of exercise. So again this chapter will give you a brief overview of what exercise has to do, what goes on in the body.
There are additional ancillary videos that I want to make sure that you do take a look at. Again exercise physiology isn't just one chapter it's actually a degree so it's very very in depth. uh and this chapter will only kind of give you a sprinkling of it so i do encourage you to go beyond this chapter to continue to train and understand a little bit more so again with chapter one what we're looking at uh is identifying the different body systems that relate to exercise and energy demands distinguish the macronutrients uses fuel for various types of exercise describe the physiological adaptations that result from exercise training, and discuss the health benefits of exercise and general principles that the U.S.
Department of Health and Human Services Physical Activity Guidelines for Americans are. And just as a side note, you might hear my dog Bishop chiming in. Apparently he's really keen into exercise, so sometimes we just have to bear with his comments.
So again, when we think about the human body, one thing you should One term you should really think about is that it's dynamic, meaning that it's ever-changing, it's ever-moving, and it doesn't necessarily, you know, work in a, you know, from A to B to C to D. It's always this some kind of system that is always trying to maintain what we refer to as homeostasis. It's always trying to maintain a certain balance, whether, you know, you're too tired, whether you're too energetic.
it's always trying to pull you back into what we refer to as a steady state. And again, the act of exercising itself challenges that steady state. So there's certain physiological reactions to the body while you're exercising, like increased heart rate, like increased respiratory rate. So these are things you should always keep in mind when it comes to exercise.
So we first think about exercise, we really have to kind of focus on the body itself. That even at rest, the body is constantly moving. It's always trying to maintain that homostasis.
So again, even when you're sitting here, even when you're lying in your bed, there is constant movement within your body. Your heart is beating, your lungs are respirating, so action is still happening. However, when it comes to exercise, it's actually exacerbating those actions, meaning it's putting a greater stress on the body again to go from a walk to a run to run up and down a soccer field to do a power lift all of those create a demand on the body and in particular an energy demand and there's three systems typically that work within each other either together or separately in order to help support those demands and again those are our skeletal systems or the skeleton and muscles the cardiovascular system as well as the respiratory system. So in regards to the skeletal muscles we know that again the act of lifting your arms, lifting your legs, it actually does require an increase in respiration and blood supply because that increase in respiration and blood supply help to deliver oxygen and blood to those working muscles in order to create some kind of movement. right to create the energy in order for that movement to happen but at the same time as we're increasing energy demand and oxygen demand to those working muscles at the same time it's literally taking it away from somewhere else so typically when we're exercising our gastrointestinal tract actually is a decrease in blood flow so even though we might not be ingesting or drinking drinking any kind of supplements or nutrients at the time that our body will be absorbing it actually slows down the process during an actual activity because the demand of energy is needed elsewhere.
So the demand of bringing oxygen, the demand of bringing different nutrients, hemoglobin cells to certain areas that are working actually changes. So your body actually shifts where you know blood flow will go. So if you've ever run really hard and you've completely stopped, you might feel like a little bit of throbbing in your arms sometimes or in your legs. That's actually your body trying to recalibrate itself.
and return to homostasis so that the blood flow path is consistent as it was before. We also know our respiratory and cardiovascular systems work at a greater demand. So again, just like I said before, you know the increase in respiratory breath that actually helps us increase the amount of oxygen that we have available to the body. We use respiration to inhale to take in the oxygen but also at the same time the expiration when we exhale that helps us remove waste. It helps remove carbon dioxide and even water molecules which typically can be a byproduct.
of energy breakdown in our body. And again, even though the gastrointestinal tract, I think sometimes people don't necessarily think about that when it comes to exercise, it becomes important because one, this is actually how we obtain nutrients from food. So we want to make sure we have a good working GI tract because that'll allow us to extract nutrients in order to...
be able to get the energy substrates that we need in order to be active. Also, when there is issues with the GI tract, again, with certain autoimmune diseases like celiac disease or Crohn's disease or IBS, that should signal to us, especially if we're working with an athlete, that there might be some energy requirements. There might be additional work for us to make sure that they do hit all their energy goals as well. So when it comes to the skeletal muscles and exercise, what I'd like to do is just break down very high level what is actually made up of a muscle cell and why it becomes so important.
So when we think about muscles, the one thing you should note is that the human body has over 600 skeletal muscles that allow for fine and gross movement. So when you think of fine movement, think of your fingertips. think of the joints of your fingers, the joints of your toes.
So for you to hold a pencil, for you to type on a computer, those would all be considered fine motor movements because it's involving the smaller parts of your body with very simplistic movements. Whereas gross movement, think of gross meaning large or encompassing large areas, and this would be things like walking, running, you know, walking up the stairs. because it's involving the larger parts of our body and they become important because you know it doesn't you know a fine motor movement can engage just as many muscles as a gross motor movement so regardless of what type of movement it is we know that our muscles have to work together as a group and that grouping is really how we think about how we're going to fuel our body and we think about how we are going to actually make sure we have enough energy to create that movement so the most simplistic of all muscles is the muscle fiber which is also known as the muscle cell this is the most basic so think about you know where muscles muscles actually start muscle fiber is that singular cell that makes up the muscle from there a bunch of muscle fibers will make up a motor unit And a motor unit is actually used to create that movement. And again, there's usually typically a nerve, and then it's surrounded by muscle fibers. When that nerve is what we refer to as innervated or it's sickled.
So think about when you switch a light switch, right? You turn it on and the light goes on. It's the same thing with our muscle fibers. Once there's a synapsis sent from the brain, it literally, quote unquote, turns it on. And it creates that movement.
And what we know is that. Each motor unit together is comprised, together will comprise the muscle cell organelles. And this becomes important because within the muscle cell organelles, this is where we find mitochondria that's used for aerobic energy production. And as well as all the myofibrils, which become really important because the myofibrils contain the sapromeres.
So the myofibrils, M-Y-O-F-I-B-R-I-L-S, really are the functional unit found within the sacramere, and that's actually responsible for muscle contractions and eccentric movement. So the sacrameres are made up of thin and thick filaments called actin, A-C-T-I-N, and myosin, M-Y-O-S-I-N. And if you think about actin and myosin, when they're triggered, it kind of creates a sliding technique. So one end of the stopper mirror will connect with another one and these two type of filaments will literally slide over which will cause either the muscle to shorten or contract or lengthen. And again the reason why we talk about the contractions and why they become so important is because the force and speed of the movement will really kind of determine what how many muscle fibers and what type of muscle fibers will need to be contracted we know that the higher the force or the speed of the contraction required the greater number of individual muscle fibers have to be recruited for contraction and again when it comes to the different muscle fiber fibers the different types of muscle muscle fibers actually help with different types of movements so the one that comprises most of the body is the type 1 fibers.
Type 1 fibers typically are about 50% of our skeletal muscles. And again, they're also known as slow twitch. And the reason they're referred to as slow twitch is because we engage with them often. It doesn't take a high level of activation in order for these fibers to be activated, meaning that very small movements will cause these fibers to contract so again these are you know things like walking running you know even just like everyday event taking the stairs that's typically engaging with a type 1 fiber and the reason why type 1 fiber becomes so important is typically any type of aerobic endurance activity will engage with these muscles so again some more movements sorry about that that was my dog you know walking and involves type one type two is referred to as fast twitch and with the fast twitch these typically are have really poor endurance capability and tend to work better anaerobically so in without the presence of oxygen so these type two the fast twitch typically will help support fast bursts of movement so again Think about sprinting, thinking about throwing a pitch really quickly. This is typically where we'll see type 2 fast twitch being used, doing a quick power lift.
That's typically where we'll see the type 2 or the fast twitch. And what's interesting is there's actually three types of type 2 fibers. There's type 2A, which comprise about 22 to 24% of our skeletal muscles. Type 2X.
and type 2C and again what's interesting about type 2 the different types that A X and C is that there's not much understood but we do know is that type 2 A fibers tend to generate more force than type 1 but it tends to fatigue much easily so again you'll typically see type 2 fibers being engaged in races like an 800 meter race or strength training workout and again type 2x typically we understand or use them way more explosive actions like a 50 meter dash or weight lifting but again there's the research still hasn't necessarily concluded what the main difference between type 2a type 2x or type 2c is there's still continued research on that and if you look at page three in the book towards the last two paragraphs. They do do a good summary of different research that's out there so I do encourage you to read that and just kind of keep an eye on that. So when we think about the cardiovascular and respiratory systems the one thing you should think about is simultaneously. That's a word that I like to think about when I think about these systems. Again because these two systems one have to work concurrently meaning they have to work at the same time.
doing the same exact job but at the same time they're also doing two different jobs so not only are they bringing energy and they bring oxygen throughout the body but at the same time they're actually removing any kind of excess waste as well as carbon dioxide so they become extremely important again the cardiovascular system comprises of our heart and our different blood vessels whereas the respiratory system consists of different airways and lungs When we talk about pulmonary ventilation, there's two phases we talk about, inspiration and expiration. So inspiration, we're breathing in, and then expiration, we're exhaling out. Again, inspiration becomes important because it allows us to engage oxygen and bring oxygen within the body. And expiration is often overlooked, but that also becomes extremely important as well because that's what allows us to remove metabolic waste as well. So what you see here this formula up here is cardiac output is heart rate tri times stroke volume.
So cardiac output becomes extremely important because it allows us to understand the actual ability of our athlete that we're working with and to understand where improvements can be made especially in regards to the stroke volume. Heart rate becomes important because heart rate allows us to understand how many times the heart will beat per minute. Typically, again, the heart is a muscle, so the more you work out, the more you strengthen that heart muscle.
And again, when you're strengthening the heart muscle, what you're actually doing is increasing the size of the left ventricle chamber. So because you're making that muscle much more stronger, the actual chamber itself expands a bit, so you're actually able to hold more blood. within the left ventricle which means the more blood you're able to hold and the more blood you're able to inject out the more oxygen actually becomes more available to the body so you actually have the ability to have higher oxygen found within the body so when it comes to the heart rate rule of thumb is that typically a normal heart rate is about 60 to 100 beats per minute or BPM and again that's just for the average person typically though the more fit you are or the higher level of fitness that you have the lower your heart rate can be and then SV stands for stroke volume and that talks about the blood the volume of blood pumped during one heartbeat is called stroke volume so again when you think about blowing up a balloon and then letting it go so the air comes out the amount of oxygen that you've actually or sorry the amount of air I should say that you've pushed into the balloon and then when you let it go the amount that comes out that total amount represents stroke volume so it talks about how much is actually pushed into the heart as well as ejected from the heart and again cardiac output becomes so important because the actual volume of blood allows us to understand how much metabolic demand the body is requiring so if the heart is beating faster it's looking for more blood that means the metabolic demand has increased. So again, when you're exercising and you're going from a walk to a run, that demand of exercise creates an energy demand and your body's response to it is to increase the heart rate because it needs more of that energy and oxygen to be transported to that area. So again, the initiation of exercise.
Again, when we talk about exercise, think about any type of movement beyond rest. So this could be getting out of bed, this could be making yourself breakfast, walking to the bus stop, walking into class, running a mile, performing a strength training routine. Anything beyond rest we consider exercise and that will require any kind of increase in muscle oxygen and nutrient demand as well as the removal.
of metabolic waste products. And what we simply know is that the reason your respiratory rate increases regardless of the type of exercise is simply because of those demands. Obviously, the more intense the exercise is, the more you'll be likely to breathe deeper. And again, that is all your body's ability in order to make sure that oxygen is present and available to help to meet the new demands or new needs. And that becomes so important to understand because at some point the amount that you need does saturate, meaning that it doesn't matter how much oxygen you can take in, that's the max capacity that your body can actually hold within its lungs, within its blood cells, within hemoglobin cells, and that's something we refer to as the VO2 max, which is that maximal oxygen uptake.
And again, this is really important because this is basically the threshold. We know at this point you can take in all the oxygen that you can in order to support it. And typically this is where you'll shift. to an anaerobic metabolism.
So VO2 max kind of tells us, okay, at this point, this is all that you can do. So again, for a sedentary person, we see people hitting their VO2 max relatively quickly because again, they're not trained. They don't have the capacity to hold more, but the more trained a person becomes, the higher their VO2 max can become. So again, with a sedentary person, we might see their respiratory rate increase about tenfold and that would be their VO2 max capacity. Whereas a well-trained endurance athlete, we could see a 23-fold increase and that would be their VO2 max.
So again, a lot of that has to do with the adaptations that exercise provides to us. And just to let you know, VO2 max is expressed as milliliters per kilogram per minute. And like I said before, it does increase over time with training.
is a limiting factor. Like I said before, there's almost like that cap. So if you think about a bell curve, this is almost like the key bell curve.
And what we know, we know that maximum cardiac output is a key limiting factor. And a lot of that has to do with our heart rate. So heart rate typically increases linearly as exercise intensity increases. So again, with that heart, because it's making adaptations itself. So the heart muscle is becoming stronger.
It actually creates more of a steady state with what it's with its heart beats because it doesn't necessarily need to beat as much to eject as much blood as before. Typically the smaller the chamber of the heart, the more times the heart has to beat in order to pump out the blood. But as soon as that heart chamber gets enlarged, again through exercise, through adaptations to the heart muscle, it actually can create a higher stroke volume, meaning it can contain a higher amount of blood. and actually push out the same amount of blood but with less heartbeats if that makes sense and again we know that trained people can work at a higher oxygen uptake before even reaching the maximal heart rate again because of the adaptations within the heart because of the larger left ventricle chambers which typically is the adaptation that happens with exercise uh think about going from like a two gallon water bottle to a five gallon water bottle you know is more beneficial, which can hold more. That's the same idea with the heart.
When the chamber gets larger, it can actually hold larger amounts of blood, so it actually can actually have larger amounts of oxygen than available. So it can actually bring higher amounts of oxygen to the working muscles, which means doesn't necessarily mean that the body has to respirate as much because it's able to still increase or hold more oxygen. And again, when it comes to the maximal heart rate, all of us typically, or most athletes will work at a below their maximal heart rate, depending on what type of endurance activity or strength training activity that you're doing.
You never want to work out a hundred percent of your maximal heart rate. That would be like, if you think about your car gauge, if you look down at your RPM gauge, you know, typically you can go through the different gear shifts of one through five and they're typically colored white. But once you hit the six, seven, or eight, that's kind of like the danger zone. Same thing with our body. If you're working out at maximal heart rate, you're actually working out at a rate or an intensity that actually can actually do damage to the body.
So now that we've briefly talked about the body itself and what happens, what I really want to go into with the next couple of slides. is actually talking about how we actually fuel this. What substrates do we use?
And the most biologically usable form of energy in the human body is adenosine triphosphate or ATP. The macronutrients, so carbohydrates, fats, and proteins will be oxidized in order to release energy as ATP. So again, regardless of what type of macronutrient you're taking in, Your body can only utilize it if it's actually releasing ATP from when it's actually broken down within the body.
And what we know when it comes to nutrients for energy, there's two types, especially within our body. The first one is glycogen, which is the storage form of carbohydrates. And this typically can be found in your liver. muscle and plasma. And what's interesting is that Each area has a different storage limit.
So most of our glycogen storages will be within our muscle. The muscles can hold up to about 300 to 400 grams, which is about 1,200 to 1,600 kilocalories. The liver has a small amount of elbow as well.
It can store up to about 75 to 100 grams or 300 to 400 kilocalories. Or our plasma cells within the body have a very tiny amount. They have about 5 to 25 grams, which is about...
20 to 100 kilocalories. So what's interesting is that under normal circumstances, if the body doesn't necessarily need energy right away, our glycogen storages aren't touched. Glycogen will typically be broken down at a much quicker or rapid rate than our fat storages, which is the second form of energy production that we have in our body.
So fat, adipocitium in particular, is short as... sort of triglycerides and adipose and skeletal muscles. So again, this is stuff that's found kind of like around our stomach areas or underneath our skids subcutaneously. And what's interesting is that adipose tissue can hold up to, if not more, of 70,000 kilocalories.
So it is a massive energy source within our body. The only downfall to it is that it actually takes quite a while to actually break down and utilize. So it's kind of like a catch-22.
Glycogen is quick, it's fast, it gets us our energy as as soon as we can break it down, but it's very limited. Whereas fat is almost like an untapped resource, right? It's almost like an infinity stone. If you watch Marvel Infinity Wars, right? It has infinite potential, but the problem is it's actually breaking it down to use it.
It takes a while. So we think about energy systems and we think about you know how do we derive this energy. There's three systems that we look at. There's the adenosine triphosphate fossil creatine system also known as the ATP PC system.
There's the anaerobic glycolysis as well as aerobic metabolism. So what you see right here on the slide deck is kind of just a high level overview of what's happening. right atp is the energy that we need so when energy is required it actually becomes hydrolyzed meaning uh water will bond to it so the hydrogen and oxygen models uh will come they'll hydra hydrolyze the model and then break it apart so that you're left with adp so adenosine diphosphate a phosphate and then there's that energy that we're using so with atp it's constantly broken down and then reutilizing again together um and the adp and the phosphate group must be rephosphorylized to atp so again there needs to be a phosphate that's added so that it can actually go back to becoming atp again and again the three metabolic pathways in order to generate atp are the atp pc system that i mentioned the anaerobic glycolysis as well as the aerobic metabolism And I wrote them in this particular order for a reason.
Typically your ATP PC system is the first system that we tap into. Think about it being almost like when you're turning on a car. That initial turnover by your key in the ignition is what kind of starts the car. The ATP PC system allows that energy for a body to start. So if you're going to be doing like let's just say high hurdles, like you're a track person, the sound of the gun going off, or the whistle blowing and you sprint and you push off those blocks that's engaging the atp pc system which shouldn't be confused with the anaerobic glycolysis this still allows us to work quickly and obtain energy quickly so think about sprints think about the 400 meter even up up to the 800 meter but again it's about a short duration that anaerobic glycolysis can't sustain the activity whereas the aerobic metabolism can that can sustain us for for quite a long time so again these systems even though the three systems they all work concurrently with each other and our body will aimlessly kind of shift through them based on what demands the uh what energy demands are placed upon the body so the first system again i'll talk about is the atp pc system so again if you're looking here What I want to highlight here is the presence of an enzyme.
Sorry, my line's a little crooked. The creatine kinase. So again, any time you see the suffix A-S-E, that actually stands for, that usually typically demonstrates that it's an enzyme. So with PC, the phosphate creatine, and the ADP, so remember, the D is di, so it's only two.
Remember, we needed another phosphate in order to create ADP. so the creatine kinase actually allows for that additional joining of the phosphate so the phosphate is actually moving off the phosphate creatine onto the adp creating atp and then a byproduct is actually creatinine so again that's something that's found within our body itself so what will typically happen is that the creatine will stay within our muscle and it will actually help replenish itself so it will then go back into our skeletal muscles and it'll bond to a phosphate and kind of being that little backup system for us there and again this is an anaerobic system meaning that it happens without the presence of oxygen so you don't have to have a high intake of respiration so again if you're thinking about the car starting or you think about you know even if you're power lifting and that the initial like snatch up that would be engaging that that atp pc system right you don't have a high in intake of oxygen right you're not changing your respiratory breath and that's because you don't need additional oxygen in order to perform this everything you need the energy is actually found within the body itself again used during intensive explosive movements and it will generate atp rapidly for very a short limited time typically it's no more than 10 seconds that's typically how much time it actually can support energy so the anaerobic glycol system is slightly different again it's still done in the without the presence of oxygen it typically is engaging with the glucose model molecule and again remember we have glycogen stored in our body so it's really those glycogen storages being broken down And what we're more interested in really is the six carbon models Because that'll allow us to create two perubic acid models So again, and the glucose really comes from two types of sources, but the key term is anaerobically Meaning again without the presence of oxygen so it either could be taken in from what we take within the body itself So it's something that we have eaten or within the glycogen storage is found within the muscle or the liver. So what we know is that typically ATP is directly generated from the breakdown process of glucose to pyruvate.
While the glucose is being oxidized, meaning oxygen is being added to it, we know that the hydrogen molecules are being removed. NAD is a coenzyme that carries electrons. and that becomes so important because those hydrogen molecules become really important to the electron transport chain and that typically we'll see again during aerobic metabolism so again remember how I talked about these three systems working concurrently and simultaneously so again these systems are working but in particular with the anaerobic glycolysis and the aerobic metabolism it's actually almost repairing the body. So again, your body's not necessarily wasting anything. It's actually taking the hydrogen and moving it over so that when aerobic metabolism happens, the hydrogen molecules are present so that it actually can create more ATP during the aerobic session.
And again, this is used within the first few minutes of intense continuous activity. So here, if you think about a tenniser, If you think about taking a corner shot in soccer, this would be all examples of an anaerobic glycolysis. Like those, that's what we, it's again, it's a short, intense activity within a few minutes.
One of the slight downfalls during anaerobic glycolysis is that there is a byproduct. So again, if you think about it, both the ATP, PCR. system as well as the anaerobic glycolysis both of them do have byproducts In particular, lactic acid is the actual byproduct that is produced.
And again, it's not necessarily a bad thing. But what we know is that lactic acid tends to be unstable at a normal body pH. And a lot of that has to do with the loss of the hydrogen ion. So it does cause the pH of the muscles to drop.
When that pH of the muscles drop, it actually creates... muscle fatigue because the glycolytic enzyme activity is actually starting to slow down. So without that presence of oxygen, without anything else to bind to that lactic acid, it's actually causing your body to stop because it's just really wearing away at the energy and it's not allowing glycolytic action, meaning for glycogen to be broken down into energy. It literally causes the sensation to stop. So what happens?
So the body Does recycle lactate? So lactate first is taken off and oxidized by the mitochondria in your muscle cells, typically within type 1 muscle fibers. And then typically what will happen is that more will get produced in type 2 muscle fibers, and then they'll couple it together and via the Cori cycle, it'll get transported to your liver.
And what happens is the lactate will travel from your muscle cells where they are down to the liver and that gets converted into glucose via gluconeogenesis so that's g-l-u-c-o-n-e-o-g-e-n-e-i-s so again if you look at the suffix genesis that means to create gluco the prefix meaning glucose so it's literally creating new glucose and that's all done during the 40 cycle and then it'll actually get sent back to the muscles for storage for glycogen and then again once that whole process happens lactate gets cleared your body will actually kind of feel ready to to move again so again if you've ever been someone who who's maybe doing some power lifting you get to a point of your body where again if you're doing bicep curls and you can't move you know that's lactic acid building up once you stop the sensation once you stop the bicep curls and maybe a few minutes has passed your arm shouldn't still be just as sore it'll actually kind of return to what we referred to before that steady state so the body is actually cleared off the lactic acid kind of reformatted it refiled it away so it's in a working order that it prefers and then it you can continue on with the activity again so the last energy substrate I'll talk about is the aerobic metabolism and this one is quite interesting Because no matter what with the aerobic metabolism, it can actually use energy substrates from any of the macronutrients, whether it is carbohydrates, fats, or proteins. And a lot of that has to do with the breakdown of the Krebs cycle and the electron transport chain. It's mainly used in endurance exercise or oxidative phosphorylation. So basically anything that creates sustained activity, so again walking would fall under aerobic metabolism, playing you know team sports like football, soccer, baseball is all aerobic because there's a long time period right you just don't play baseball for a minute or two and then you're done you have to sustain it for hours.
One product of the the aerobic metabolism is acetyl-CoA. And this is important because it's a metabolic intermediate from both the glucose and fat oxidation that's ultimately oxidized via aerobic metabolism. And this is where we see the hydrogen models come back into play that we use during the anaerobic glycolysis.
So again, those hydrogen models were kind of shuffled over here via the electron transport chain to help generate the ATP. via the Krebs cycle. So again during the Krebs cycle that hydrogen molecule is needed and it's shuttled over by NAD and FAD and then once those hydrogen molecules are present we actually are able to generate ATP and then oxygen is the final hydrogen acceptor and it actually will form water.
So with the electron Transpartine it's actually the most efficient way our bodies produce ATP because there's no metabolic byproduct that produces a teeth So remember during anabolic glycolysis it actually created lactic acid But during aerobic metabolism the byproduct is water which doesn't have an effect on the actual body itself. So that's why we can sustain aerobic activities for a longer period of time. And it's the most efficient energy system.
And again, like I said before, all metabolic systems work concurrently, so one doesn't shut off while the other one turns on. Pretty much all the systems are working at any given time. And what this chart below kind of shows you is the overall contribution of ATP and oxygen availability within each system. So again, when it's working without oxygen, so that's either between the ATP PC system or the anaerobic glycolysis, we know there's a rapid oxidation of the six carbon glucose molecule, which will give us 32 ATP.
Typically at rest or low intense aerobic activities. Fatty oxidation is what really gives us more ATP per gram. And then as activity increases and the intensity increases, your ATP demand is higher, but your oxygen is limited, which is why carbohydrate tends to be a primary tool.
Which is, again, if you think about the anaerobic glycolysis, how quickly we're breaking down energy, that should help you understand why glycogen stores become so important. So hopefully this chart kind of demonstrates to you the... the intermixing of the systems and why in particular it's so important that we pay attention to what we intake from a fat and carbohydrate perspective. I think oftentimes we think about protein being really important with our athletes and it is but not when it comes to an energy source. Typically fat and carbohydrates are number one sources for energy.
Protein does have a benefit but we'll talk about that in a bit. So when we talk about fatigue, we're not talking about the fatigue you probably have right now listening to me thrown on. It's more about what happens in the body, right?
What happens when you hit the ability to stop producing force because either you depleted your energy stores or maybe you don't have enough oxygen. Basically, ATP, the demand that you need, your body can't produce. And that's typically what happens when it comes to fatigue.
When we think about muscular fatigue, it's the inability to produce force at a muscle level. So think about, you know, if you're doing bicep curls of 25 pounds and you get through 12 reps, you want to get to that 13th rep, but you literally cannot pick up your arm. That's muscular fatigue. At that point, what happens is that the energy demand that is required for you to lift that weight, your body can't eat. It's probably burned through all your stores and, you know, it just needs to take a rest in order for it to kind of reset.
itself. Typically at rest or low intensity ATP will be produced without fatigue inducing byproducts. So again lactic acid typically won't be produced at very low intensity or even at rest. It's just that with the higher intensity and the higher energy demands the more quickly your body has to produce that energy and that anaerobic glycolysis typically is where we see that lactic acid or lactate being produced. Short-term fatigue, again, typically isn't necessarily something that we're concerned about from a counseling perspective if we're working with our athletes.
We know typically it will happen when it rises in exercise intensity, and it can interfere with energy levels. So again, while we're working with our athletes, whether it's pre-season or during season or pre-event, You know, this is something that we're going to be monitoring throughout the training schedule, making sure we're noticing that, you know, when you're increasing their training or periodization schedules, you know, is there an increase in fatigue? Is there not?
And again, there are ways that we can kind of combat that. What we do try to avoid is long-term fatigue. Typically, we see this more so in endurance athletes.
And usually, this is a sign of glycogen depletion. And this is something that we try to avoid completely because once the glycogen stores are depleted, the dietary carbohydrate absorption and the gluconeogenesis can't keep up with the skeletal muscle ATP demand. And this is where movement will stop. People have collapsed simply because their body basically says, I can't do this anymore and needs to stop all activity so that it can actually have the energy to help support a heartbeat, for the brain to think, the lungs to respirate. So this is almost like it is a wave.
In a way it's protecting itself. So when it comes to exercise, there's certain principles that we do follow. Because remember, exercise training itself is an adaptation process.
You're placing stress on the body and the body will respond appropriately. So again, when we talk about principles of exercise training, we think about training itself, fueling, rest and recovery. So typically rest and recovery aren't always thought about of the training process.
But research has shown that it's actually becoming just as important as well as fueling because we know that over time over training or under training can result in an undesired effect and it doesn't matter what level you are whether you're a beginner a novice or advanced these four principles need to be part of your training regime and what we are trying to to minimize or control is the detraining effect. because what we know is that over time lower training load or inactivity will cause a physiological demand especially within our cardiovascular system we know that typically three months of a detraining effect you can lose up to 50 percent of your vo2 max so it becomes extremely important not only to focus on what you're doing pre-season during the season but also what you're doing post-season because again when you're working with athletes especially those who might be seasonal Those who might, you know, have to train for certain seasons. So, for instance, like this past summer, we had the Summer Olympics.
Those athletes weren't training, you know, the winter before. They've been training for years, you know, and now that the Summer Olympics are done, it doesn't mean they've completely stopped. You know, they might have the Pan Am Games coming up in two years.
You know, we're bringing them up to a level. We have to make sure we're safely bringing them back down as well, that detraining effect, because we want them to maintain the gains that they've had. even if they are decreasing the intensity that they've been training at.
So when we think about the principles of exercise, the first that should really come to mind is an individuality. Both genetic and environmental factors contribute to body composition. You know, and again, certain body types will be more adept.
So again, the ectomorph. is generally tall and lean, the endomorph tends to be rounder, and the mesomorph is somewhere in between. So people will respond differently to different training programs. You know, if you're working with someone who's very tall and lean, you know, they might never be able to, you know, quote unquote, bulk up.
You know, if you're working with someone who's an endurance runner, and they tend to be, you know, a mesomorph, they might have difficulty, you know, increasing their time. just simply because their torso and their legs are the same size and you know typically those who have longer legs have the ability to run longer and faster you know those are things that you can't necessarily control for but you can think about while you're creating your programs there's also specificity which is a word i really struggle with saying sometimes physiological adaptations and performance so again Whatever the sport they're training for, you want to make sure their training program responds to that. So while you might have someone who's training for a half marathon, maybe one or two days during the week, you might have them cycle or you might have them swim in a pool. The majority of the program isn't going to be swimming or biking because a majority of the program should be getting their body used to the physiological adaptations that happen with running. So again, when you're running for a marathon, you're training your body to run 26 miles at once.
So you need to be doing certain mileage a week so that your body gets used to the pavement, you know, hitting its feet. You know, and again, when your feet are hitting the pavement, there's that force that your body is pushing down to the ground and that the ground is actually pushing back up. So you're getting your ankles, your shins, your legs used to the constant movement and pounding. So again, so that you're avoiding any kind of injury over time.
Physical stress is specified to the system. So again, if someone's running a marathon. you're not going to have them train their cardiovascular system by being in the pool because again being in the pool while it actually might be a better cardiovascular training workout you're missing that gravitational force that you're going to need in order for the body to create those physical adaptations to continue the event again there's progressive overload so in order to see improvement you need to be quote unquote overloading the system meaning that you have to be pushing yourself you know each time a little bit more so for example if a person wants to gain strength He or she may initially bench press 100 pounds for eight reps and then over time they might increase it to 12 or 15 reps before fatigue.
So there's always what we refer to as incremental training programs so you're not going to necessarily you know pick a point and start there. You're always going to kind of work your way up there and this becomes especially important in resistance training and with endurance performance it's more about sustaining the time. So you're always increasing time with resistance training it's more so you know either increasing the intensity via weight increasing it via sets you might be focusing more on eccentric movements so you're creating you're creating that variable within the resistance training with endurance training it's more about keeping the steady state over a certain period of time so if you're someone who's a swimmer and let's say you're going to be swimming 100 meter fresh stroke you're not going to start off swimming 100 meters you might start off swimming 10 meters then 20 meters then 25 and consistently trying to improve your times for each and there's also variation or periodization so again most elite athletes are following a training schedule not necessarily just in season but also pre-season and post-season so we're looking at different time blocks And this becomes extremely important, especially when it comes to nutrients and fueling, because typically you can actually change nutrients and fuels based on results within that small periodization.
So what we find, especially within training programs that have that periodization, especially with pre and post programming, we can actually do a much better job of preparing their fuel. And that becomes especially important for those who might be doing endurance activities. And it helps us minimize the number of outcomes.
So again, our main goal or outcome with multiple athletes are going to be able to perform at their peak performance. That's really a main goal. It's not going to be trying to figure out exactly their energy needs, going to be figuring out at what point their energy needs taps out.
It's really about just getting them to an optimal peak performance. And what's nice too about the variation in the periodization, you have that time frame. So you have the understanding of where you want to hit your goal or your metric. So what we know about adaptations to the body, we know there's typically two types of adaptations based on the different types of activities.
So usually we kind of categorize exercise into two main categories, endurance training or resistance training. So when it comes to endurance training, we really see more adaptations happening within the cardiorespiratory system. So again, we know that from a cardiovascular perspective, the left ventricle internal space increases stroke volume. So again, that left ventricle chamber will increase in size. By increasing in size, it allows us to have a larger stroke volume, which means that we can pump out more blood and have more oxygen available to the body.
We also know that there's an increase in type 1 muscle fibers or cardiac output. It really doesn't necessarily change much during rest and sub-muscle exercise, but it will increase considerably during exercise and training. And a lot of that has to do with the resting heart rate, so it does decrease with endurance training. And the rate can be lower, about 40 BPMs or lower.
So again, an average sedentary person, typically at rest, their BPMs are about 60 to 100. beats per minute but within someone who has a very strong cardiovascular system and who's an endurance athlete we can see that resting heart rate as low as 40 to 60 beats per minute and what's interesting is that because we've got that that lower beats per minute during exercise when the heart is stressed it's still not raising at a high rate so it might increase to 60 to 70 beats per minute which does allow us to have a higher vo2 max So it allows our oxygen capability to actually increase as well. And also another benefit is that the resting blood pressure tends to be reduced and a lot of that has to do with the amount of blood volume that's available because that enlarged heart chamber, that left ventricle interspace, more oxygen is being pumped out, more blood is being pumped out, but more efficiently. We also know there's increase in capillarization. So if you think about capillaries as being really thin vessels that connect across muscle and heart. when you're exercising more and more created so especially that becomes more important especially amongst the heart because it allows for more blood volume to be available plasma volume and an increase in red blood cells and again red blood cells are really important because that actually helps us carry oxygen throughout the body as well and we also know that there's an increase oops Sorry, I can't go back on the slide.
So with resistance training, the adaptations are slightly different. We tend to see more gains when it comes to our skeletal muscles versus our cardiovascular system. What we know is that there tends to be improved neural adaptations. So meaning that there's an increase in motor unit recruitment, meaning you're able to generate more force and even faster.
And it also decreases neurological inhibitions, meaning that your body doesn't necessarily struggle. So if you think about it, if you like picked up a 10 pound weight for the first time, there might have been that little hesitation. But once your body starts adapting to it and gets stronger, you kind of pick up that 10 pound weight as if it's nothing.
We know that over time, increased strength will lead to muscle hypertrophy in later stages of training. it also increases the size of the skeletal muscle fibers so it'll also increase as well actinomyosin filaments from hypertrophy so you'll be able to recruit more muscle cells and more muscle fibers again leading to more the ability to lift more weights or have more dense muscle fibers actually develop So again, we talked about all these positive gains and all these positive movements. But remember for every, so not to quote Star Wars, but to quote Star Wars, you know, there's always a light and a dark, there's always a good side and a bad side. So again, with exercise, there are many good adaptations within their body, but there's also the negative side.
There's also the, what happens if you train too much? So again, we talked about the principles of training. you know being training, fueling, rest and recovery and that will help lead to increased performance.
But what happens over time is that we know that a phenomenon of overreaching can occur and this really talks about excessive training results and short-term performance decreasements. Usually this is something that's short-term that can happen over several days or several weeks. This is where you'll typically feel overall end muscle muscular fatigue. So what we mean by overall fatigue, it just could be, you know, getting out of bed and just kind of feeling tired or in a fog throughout the day, you know, and muscle fatigue obviously, you know, sometimes you might have heard of the phenomenon of DOMS, delayed onset muscle soreness. So maybe you had a really great workout one day and then you woke up the next morning and you were trying to get out of bed and it became extremely difficult.
I know in the past, especially when I used to play volleyball in high school, we'd have really long training sessions. I just remember my legs being on fire, you know, from playing for so long that I would typically have to walk up the stairs backwards, you know, just because my quads were so sore. You know, that's an example of DOMS, like delayed onset muscle soreness. And again, a lot of with overreaching, it's usually short term.
It's not something that can cause injury. It can be kind of I want to say reversed with proper training, rest, hydration, and adequate carbohydrate and protein. And again, this is really where protein comes into play with our rest and recovery.
This allows us our muscles to repair. It allows our, you know, again, protein, even though it does have an energy requirement, it's more so using the amino acids to help rebuild. So that's where it becomes so important, more so is in our recovery phase versus our energy requirements. Box 1.1, found on page 12, gives you a high-level overview of what overtraining can look like.
And slide 22 and 23, I'm not going to go over, but it's just a high-level recap of the presentation today. So thank you for listening all the way to the very end. I will try to work on my presentation voice. Again, if you have any questions, please be sure to submit them via the forum. And I will see you in class next week, sorry, on Friday.
And please be sure to make sure you take the chapter quiz in order to get credit for it. Have a great day.