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I'm not going to go far into this but I hope that I turn a couple of you
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at least into as big as nerds as I am. You think I'm kidding, I'm not. I
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have a Sheldon bobblehead on my on my bookcase in my office, that's
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what my friends call me is Sheldon, I'm like, "That's great, I hope I'm a little
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bit more personable." Anyway I hope I turn you into a couple nerds and
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after you take your kinesiology course and you passed your final, because I want
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you to pass your tests, you will look into some of this stuff, the
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nervous system, you literally could spend a lifetime studying a single aspect of
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the nervous system. Central nervous system is what? Brain and spinal cord.
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What is the function of your central nervous system? This is the thinking or
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the control center, even your spinal cord. Your spinal cord does a fair amount of
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"thinking." Here's an interesting experiment that I never want you to do.
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If you touch a hot stove, you ever done this? Everybody's done this,
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touched a really really hot object, you will pull your arm away before you have
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the conscious thought that it was painful. Fact. Part of that has to do with
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the fact that your pain pathway is slower than your muscular pathway. Part
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of that also happens because this is a withdrawal reflex and a reflex happens at
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the spinal cord level. Crazy huh? You touch something hot, your spinal cord
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doesn't even get the signal up here, goes "pink," then you go "ow." You don't go "owwww."
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That doesn't, it doesn't happen that way. Your peripheral nervous system
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is just the pathways in and out, that's it. That makes sense? So your peripheral
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nervous system is what we know of as nerves.
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You have you afferent and efferent nerves, you have your sciatic nerve,
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what's your sciatic nerve? Yeah, it goes down your leg, it's a group of axons.
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Axons go to neurons, but those axons are part of your your peripheral
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nervous system. Afferent means what? Goes in yeah, efferent exits. Good call.
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Efferent, E, exits. Efferent go to muscles for the most, as far as we're
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concerned for now, they also go to organs and stuff Afferent is sensory
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receptors. Everything from our eyes which we know as a sense, to touch, to even
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little receptors inside of joints that tell us how much pressure is within that
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joint, what position it's in. You might have heard of muscle spindles
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and Golgi tendon organ, that's all afferent information. So neural control
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of human movement, receive information. When you think of motion, you could
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break it down to receive information from sensory afferents, interpret
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organize and plan, and then activate motor units via of the motor nerve. So
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you have to sense your environment and then react to it, your body is
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continuously doing that. The complexity of that is staggering. The fact that we
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move at all sometimes is just staggering to me, all of this stuff working together,
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and how if you mess any of that up at all, that all changes. So what is a motor
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unit? Anybody? Let me take a step back, how much you think I can
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curl. Be generous.
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30s? That's not generous, I'm 6 foot 3, 225 pounds. 70s? Now you're being too generous
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but thank you, that's at least a little closer. I think with 70s with bad form, I
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could swing some 70s up. Yeah. Do you even lift?! You know who I'm
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talking about? You ever watch Bro Science Life? You have to watch this guy,
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This guy is hilarious, he's created a character around the worst gym bro that
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you can possibly think of. He is on a whole other level hilarious. He has a
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whole video on how to get out of leg day, you get what I'm saying?
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That's who this guy is, he'll go over the squat rack and start doing
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curls with the barbell. It's awesome. Anyway, so maybe I
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could cheat curl 70, let's say I could curl 60s, 50s probably with good form,
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so then the question becomes when a muscle fiber fires it fires completely.
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There's no dimmer switch on a muscle fiber. You kind of know this.
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You hit the the threshold, the activation threshold, create an action
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potential, the muscle fiber fires, it contracts. It doesn't go "little
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contraction," it just contracts. So then the question becomes if I can curl 60s, I
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can generate that much force, how do I curl this marker without throwing it
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through the ceiling? You get the the problem here? If I put 60, lifting 60
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pounds worth of force under this marker, what would happen?
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Yeah so that's a problem. How do I control that? How many fibers I recruit.
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Now how my body organizes that is through something called a motor unit. So
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you're exactly right, the only thing is is we don't have a nerve going to every
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fiber. That actually doesn't make sense. What your body's done is it's, you see
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how this is worked out? This is a nerve and I'm going to attach that to four
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fibers, so when that nerve fires, all four of those fibers
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will fire. And I might have bigger motor units than that, that have 100
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fibers, 120 fibers, my curling 60 fibers, and I may have a couple fibers there are
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only one, for really finite movement. Does that make sense? So based on how many motor
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units I recruit and what type of motor units I recruit will be dependent on what
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type of force I apply. Just remember, as soon as that motor unit fires, it does
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what? Fires completely, it contracts as hard as it can. That's it, on off. You'll
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find that a lot of things in the body are on/off, yes/no, facilitate/inhibit,
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works a little like a computer, right? 0 1.
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Neuromuscular efficiency. This is a little foreshadowing. I know this
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morning I'm doing a lot of foreshadowing, giving you a little bit of why you
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need to keep up with this. This is the definition of neuromuscular efficiency:
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the ability of the neuromuscular system to allow agonists, antagonists, stabilizers
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and neutralizers -which if you haven't learned that yet you will tomorrow or
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you will later in your class, those are the different roles a muscle
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can play - to work synergistically to produce, reduce and dynamically stabilize
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the entire kinetic chain in all three planes.
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You got part of that definition down already, you know the all three
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planes part. Now we just got to fill in the rest. All right so there's a little
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workbook page in there called "Putting It All Together. I think the workbook page
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is actually even nicer than that is, in the essence that you have a word
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bank in the bottom. I want you to take a couple minutes and fill that in.
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Alright so the blank receives information from the environment,
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organizes that information and initiates a motor program. The nervous
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system. Movement occurs when a muscle contracts, the muscles pull on? Yes
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tendons. Everybody always goes bones, and I'm like um. The tendons, in turn, pull on
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bones, the bones move as dictated by the joint type and structure, joints are
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supported by ligaments which connect bone to bone. Now if you're going to get
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really nerdy, part of this is putting in your reps. You know what I'm talking
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about? You put in your reps at the gym right, how many you guys go to the gym,
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regular basis, good, good. Good everybody should go to the gym, we need to be
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healthy. You got to put your reps in at the gym, you got to do your work.
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Part of knowing this stuff is doing your reps as well. So one thing you can
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start doing to yourself is imagine if you just thought about that for one
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joint motion. Let's say I did a curl, what muscles will do elbow
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flexion? What if, if we wanted to take it one further which I know is not for this
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class, what nerve innervates those muscles? Oh oh right what are the tendons?
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Tendons are going to be named after the muscles that's not too hard but at least
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be able to visualize what those tendons look like. What joint does it cross? Let's
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just pick one, we said elbow, what are the names of all the ligaments that
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cross the elbow? You get what I'm saying?
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Imagine if you did that and you just took one joint a day,
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one joint action a day. How long would that take you? 20 minutes maybe, you got
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Google, you got Google and my website, you have it easier than
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the previous generation who would have to go to the library look this stuff up in
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several text books. Imagine if you did that with one joint, just sat
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down wrote it out, you tried as much as you could by memory right, and then
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you found the rest on Google and wrote it down. The next day you tested yourself
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on that joint to make sure you remembered it, and did one new joint. How
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long would that take? 20 minutes a day. How good would you be at your anatomy at
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the end of one year? You'd be crushing. You would look at any
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kinesiology class and go I got this, it wouldn't even be a problem.