(air whooshing quietly)
-: So let's look how we can take the information
of a resistance profile in the moment arm,
and use that to modify our programming
or manipulate the way that we're gonna do an exercise.
So we looked at the stickman squat,
and now let's look at a real human here.
So we have Austin squatting, heels flat on the floor here,
and our goal is quads.
We wanna get as much load on the quads as possible.
So in this position, with Austin's biomechanics,
so the length of his levers,
and the amount of mobility he has at that ankle,
he's able to get the knee that far away
from the line of force.
So not very big.
If you wanna compare it to the hip, right?
The hip is still further away than the knee,
meaning this squat is still a lot of glute.
It's a lot of hip; it's not a lot of quad.
If I wanna get more quad,
one of the things I could do is to use a heel lift.
I could use like a wedge,
or I could put the heels on a plate.
So over here, we have Austin with his heels elevated.
And what that does is it's essentially us
kind of artificially changing his mechanics.
We're acting like he has more ankle mobility
and longer tibias than he really does
by lifting up that heel.
What that does is it allows us
to drive the knee further away,
increasing the moment arm for the knee,
decreasing it for the hip.
So now this exercise has become more quad-dominant,
so the quads now can actually do more work,
and the glutes do less.
So if my goal is quads, not hips,
well then, this is a better exercise, right?
Doesn't matter if it's a metabolic approach v neurological,
if my goal was to get that effect in the quadriceps,
or to simply train knee flexion more,
for a quality, for sport, or whatever it may be,
now I've put myself in a position
where I can better focus on the knee joint
and the quadriceps muscle group.
So just small variations that we can make in body position
or manipulations in using tools like a wedge,
we can take a squat and make it individualized
for the person and the goal
that we happen to be looking for.
Now both of these exercises are still gonna be
hardest at the bottom and lightest at the top,
but what we've changed is proportionately knee to hip,
like quad to glute, where that work is going to be done.
If we look at another example,
so we're gonna look at a dumbbell press
versus a dumbbell fly,
and look at the change of work there.
So we have like the mid-range position
of a dumbbell fly here, right?
So it's a pretty big moment arm.
Yeah, basically, we're gonna end up,
by the time we get to the bottom over here,
the full length of the arm.
Now what I want you guys to understand
with this moment arm thing
is that when there is essentially no moment arm,
we're gonna call that stacking.
So when the line of force is right over the joint.
So in this case, Bryce has the dumbbell
directly over his shoulder joint.
So that weight is applying almost no force
to pull his arm that way.
It's simply just pushing down.
So that stacking makes that dumbbell extremely light
in terms of the amount of work the pec has to do.
As soon as his arm starts going out,
the amount of work that pec has to do drastically increases.
If you want a comparison,
if we actually were to do the math
for this five kilo dumbbell over here,
at the stacking, we could estimate that
maybe that pec is having to support about two pounds.
Forgive me from going to kilos to pounds,
but you'll get the point.
As we go to a fully lengthened position
where now we basically have a moment arm
that's equivalent to the entire length of Bryce's arm.
And we did the calculations for that,
now that dumbbell is imparting about 44 pounds
of rotational force, torque, at that joint.
So that's that much more work that the pec
and the shoulder joint are now having to do there,
compared to here.
So when we use something where we're using a dumbbell
or whatever, and we're using our entire limb,
a very, very long moment, there's gonna be--
there could be a drastic change in the amount of resistance.
So that's a huge change in the resistance profile, right?
This being very, very little, and this being quite a bit.
If we were to take the example,
and we were to look at comparing a press
versus the bottom of a fly,
the press, because now it's only the length of the upper arm
instead of the entire arm, is gonna be about half as much,
and then when you add in, too, the fact that,
okay, in this position
maybe you can use a little bit of triceps,
or if that dumbbell where you were to let it come in
the way to get even closer,
that moment would get even smaller,
which is something that a lot of people do
when they quote unquote cheat while pressing
is they bring those dumbbells in.
You'll see that this is significantly less load.
But, how many of you guys can press
way more than you can fly?
Everybody, right?
And that is because
this is a much better mechanical advantage,
because there's not that long of a moment arm.
Here, it's a really long moment arm,
so that same weight would be applying a lot more force.
So everybody's gonna be able to press
at least probably double, if not more,
than what they can fly,
simply because of the change in resistance profile.
When we get into machines that pivot,
now we have to look at something different,
because that line of force is not always gonna be constant.
With gravity, the line of force is always straight down.
But when we use a machine, like a leg curl, leg extension,
something that's gonna move around a pivot point,
it's gonna be the force that that machine is trying to move,
the pad, that's the line of force.
So up here at the top,
that line of force is almost horizontal.
It's essentially like 90 degrees from the tibia here, right?
So that line of force is here.
And as he goes through that motion,
and he starts to go down,
the line of force of the machine is gonna change,
because the machine's gonna be pushing that pad
in a different angle as it rotates.
So if you can imagine that line of force is here,
what it's gonna be doing is it's gonna be curving
like that as the machine goes.
And if you look through our three positions here,
you can see that we eventually get to a point
where the line of force is pushing straight down.
But it almost changes 90 degrees throughout the movement.
Now, if we look at just the comparison
between that line of force and the knee joint,
so the distance between the knee and the line,
the knee and the line, the knee and the line,
without even putting anything on there,
I can tell you that it's always going to be the same,
because his legs never change length.
The pad stays at the same spot on his leg.
So in terms of just Bryce here doing this movement,
the moment arm never changes,
so the resistance profile would be a horizontal line.
It would be the exact same
every inch of that range of motion.
So what's going to impact that resistance profile
is not the length of Bryce's leg here.
It's actually going to be the cam on the machine.
So if you look, there's this thing right here
that the cable's going around.
That is the cam.
So the shape of that cam is going to determine
if there is any change in the resistance profile.
If it's a straight circle, probably not any change,
because there's now a whole other moment,
which is gonna be what this cam is pivoting on,
and how far that cable is away from the pivot point.
So if you imagine that I had an egg,
and I put a line in the middle, right?
And I started spinning that egg, right?
The tip of that egg is always gonna be furthest away
from the line, and then say, the back side
and the sides will be closer.
So when you look at a cam, there will be a point
that sticks furthest away from the pivot point.
When the cable is on that point,
that's where that exercise is going to be hardest.
That's where the resistance profile is going to be greatest
for that particular machine.
This will look a lot easier
when we get to look at that in person at camp.
But just understand that on these type of things,
where the moment arm
in relationship to the body never changes,
you're then gonna have to look at the implement and see,
is there a change going on there
that's gonna determine what that resistance profile is?
So an important point to walk home from this,
especially for machines, is that every machine,
that's not its base function on its own.
We need to look at, what are my biomechanics?
What are the biomechanics of the machine?
How does my anatomy set up with that particular machine?
Is it ergonomic or what not?
But there's lots of different ways
that I can use every piece of equipment
and make small changes to where my body is,
or using a wedge or something like that.
Like even though a squat isn't a piece of equipment,
we showed just by a small change,
we can drastically change that.
And that'll happen when we change torso position,
when we change our body position,
and different machines
that have a nonlinear resistance profile,
because by moving our body,
and moving the range of motion
that we're using that machine in,
we'll be using a different portion
of that machine's resistance profile, okay?
So we need to look at every machine as an optional tool
that is, we'll say like a Swiss army knife.
It can be used for multiple purposes and multiple goals.
You could use the same machine possibly
to overload a muscle on multiple points
by simply changing the variables of the rep
and your positioning and your setup in that machine.
A note for the future.
So we're talking a lot about the mechanics of machines here,
and we're talking about our levers and things like that.
All of this external stuff,
there is another portion of the equation,
in terms of how much tension is in a muscle
at any given portion of the range,
and that requires us to have a strength curve.
So every muscle is gonna have a unique strength curve,
which is, we'll say, not really understood.
Most people are under the perspective
that all muscles have this strength curve
where they're just like they're strongest in the middle,
they're weak in the extremes.
And that's not necessarily true.
Muscles have different development,
they have different architecture, so they're designed
to actually function mechanically different
depending on what their function is in the body
and the joint that they're around.
So in the advanced mechanics course that I will be teaching,
we will look at the internal factors here.
However, that's a lot of work to get into.
For those of you guys that wanna take it to this level,
to be able to program really well,
to be able to get somebody to lose body fat,
to be able to get somebody to be stronger
and put on some muscle
and do all the things that you need to do,
especially at a general population level,
just understanding how to complement exercises
is gonna be leaps and bounds above
what everybody else is doing.
So I just want you guys to know
that there is another piece of this equation,
but the information that you're gonna have now
is gonna drastically elevate the level
of your workout program design on its own
without having those last pieces.
I'm not saying that last piece isn't important.
I, of course, really like those details
and like to nerd out on that stuff
and really understand optimal loading
for every piece of tissue.
But it's just a lot more work, a lot more time,
to be able to learn all of those concepts as well.
So that'll be important when you're looking at
basically taking advanced trainees to the next level,
being able to basically squeeze out
that last bit of their potential.
Then you really need to know those things.
So once you're working,
if you're working with physique competitors,
or you're working with elite athletes,
that's definitely powerful stuff to be able to use
in advanced programming.
If you're working with people
that are just started training,
that's gonna be overkill, right?
That's just gonna be information
that isn't really paying off yet,
until they get to a point
where they can really take advantage
of some more advanced programming.