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