You're going to lose.

All right I'm going to be presenting to
you today an inch a limb compensation

strategies due to constraint.

During human hopping this work was
done in collaboration with Dr Young

in the comparative neuro mechanics.

Maybe.

OK.

You know clickers on
because it's clicking.

OK technical difficulties every day

we're experiencing a variety of different
constraints and just normal everyday life

some examples of constraints that can
limit and restrict locomotion include

fashion imagine wearing high heels or
walking around in the ski boot as you're

walking to the lodge to get hot chocolate
or thought a thought experiment

another place that we see in motion
constraints using an ankle foot or though

says the goal is to help treat someone
that needs help and assistance and gait.

But this can also limit their
income range of motion or

pathologically someone that's had a stroke
could potentially have an altered

range of motion at their ankle
as a result of this condition.

So how do we overcome these constraints.

Well previous literature has suggested
that compensate compensatory strategies of

the lower limb conserve whole in variables
rather than considering the individual

can the magic kinetic kinematics and
kinetics of joints.

So examples of these low level goals
include leg orientation leg length

like Stephanus and vertical force.

But what's happening when an ankle
constraint is applied what goal and

what level goal is occurring and is
there goals occurring at the limb level.

Well before we answer that
question we need a model

we need an experimental model in order
to see what's going on in locomotion.

So we can use hopping as
this experiment to model.

The spring must model is used to predict
the hopping and dynamic hopping and

running dynamics of the leg.

So using the spring mass model idea.

We can take three joints
think of the knee and

the hip and you can reduce it down
to just one degree of freedom

because you just have a simple mass
going up and down on the spring.

But what this doesn't address is
what's occurring at the joint levels.

So that's what we're going
to look at in our study.

So the purpose of the study is to study
how the joints compensate and interact.

When a comedic kinematic constraint
is applied to the ankle.

We have pasta size that the joints
are going to be conserved.

We're going to be coordinated
in order to conserve leg length.

We see that this is going to be
predicted that this would occur

on two different levels.

The first level would
be across conditions.

So when we compared our controlled
condition to our constraint conditions

we would see that length was conserved
between these conditions and

on our second level we wanted to look
at conservation across hoppin cycles.

So if we looked between one condition
what was occurring from hop to hop to hop

we would see that the enter
cycle joint variance

would be coordinated in
order to conserve likely.

In order to test this hypothesis.

We use the following procedures
that had been approved by RB.

We had ten subjects hot being at two point
two Hertz we collected three trials that

twenty seconds each for for each condition
and then we randomized the order of

the conditions for conditions included
hopping with a free ankle constraint.

Hopping with a dose of flexion blocked
hopping with player flexion blocked and

hopping with their select.

And blocked at the same time.

So we used a six most six
camera motion analysis system.

In order to collect kinematic data and
we used Matlab in order to process and

analyze this data and then used

in order to perform assist it's historical
analysis we used paired T. test.

So before we move on.

I want to clarify a little bit more
about these conditions we have

our three condition or control.

So we have unconstrained motion and

then we have three different
motions where we had a constraint.

So looking at this images where you see.

The gray image that is where you have
been available range of motion for

each condition.

If you see a color red green or blue that
is where the motion was blocked and where

there is a limitation so the person was
unable to move their ankle in this range.

So our first condition when we were
free thinker was unconstrained and

they're able to move through
their full range of motion for

our second condition we have
the planner flexion locked.

So they're able to move and
dorsal flex their foot but

their limitation was occurring in their
planar flexion range of motion so they're

able to move their foot up but they
couldn't go past this block right here.

This trend follows through for the door
selection blocked condition in this

condition we limited door selection and
then we looked at the door selection and

planar flexion box conditions together we
actually limited both at the same time but

to a lesser degree so.

This is actually our
least restrictive motion.

So now we're going to look at what
was happening at the level of cross

conditions this first before we go on is
going to be the end goal joint trajectory

that was measured on the Y.
axis you have the ankle angle on the X.

axis you have the percentage
of the hopping cycle and

you'll have a vertical line on the graph
that is going to split the differences

between our stance face and our face and
that will kind of occur throughout these

graphs showing right now is the kinematic
trajectory of the three contests.

When we applied our plan or flexion block
what we saw were differences in the mid

in the beginning and the end of stance and
then through aerial phase

not think about what was happening with
the plane or flexion block condition.

So you're trying to point your foot down
during the beginning and the end of stance

and also during aerial space but
the planet conditional is preventing this.

Hence that's where we're seeing
the differences between the ankle joint

directors.

Next looking at the dearth of
selection blocks trajectory and

we see differences occurring throughout
the stance which is now in this condition

we're blocking flexion So the pair said it
was not able to dearth of their foot and

so that would be occurring during stands
when you're compressed in flexing your

angles in order to absorb your
energy as you're hopping.

But this motion was being prevented.

And then we had our door selection and
planar flexion block if you notice this

kind of falls in between our two extremes
so we had a lesser degree of block

occurring for selection and planar flexion
but we only saw a significant difference.

During the state space.

So when we look at all the joints at
the joint level and what's going on.

We see some differences occurring like we
saw with the ankle joint the constraints

that we applied were actually working and
were affecting the ankle joint trajectory.

At the expected times for the knee joint
we're also seeing differences at the knee

joint where you see increased flexion
across all the different conditions and

the differences are just that different
from the different time periods across

the hopping cycle and for
the hip joint We only see a difference for

the planer flexion block condition and
we kind of contribute this

high variability in the ankle or
in the hip ranges during hopping.

So that was what was going on at the joint
level what was happening at the hip level

when we're looking at trajectories we see
that leg length is not considered for

the door selection block condition and
the planar function lock condition.

This is where the differences were in
this graph in its normalized length so

that we could compare across
the different heights of subjects.

So we more or less normalized this leg
length that was measured to the hour and

atomic alike link that we
measured prior to the study.

So we can compare each subject.

And it's also noted that
the selection plan of action

box condition was conserved.

There weren't statistical
differences occurring.

This is there is a lesser degree of
constraint being applied and due

to this lesser degree of constraint the
leg in the system was able to compensate.

So we looked at what was going on across
conditions now are going to take a step

and look at was happening across hopping
cycles in order to do this we're going to

use the uncontrolled manifold analysis
in order to see what was happening for

our second prediction.

So will we said was that leg
length was going to be conserved

due to joint coordination from hop to hop.

And so this you seem analysis was
used in order to quantify the joint

coordination that was of course
occurring across hopping in cycles.

In order to see if joint
coordination was occurring.

We use the index of motor abundance or
the I Am A.

What this is a metric
that is the result of

the output from the You seem analysis
method and the metric says that is used

in order to determine if
Joint Coordination is occurring.

So if I am a is greater than zero.

We see that our hypothesis was accepted.

So.

The joints are being coordinated at this
point in order to conserve like going.

If I may was less than or

equal to zero the our hypothesis
is going to be rejected.

So looking at our results for
leg length I am me on the Y. axis you'll

see leg length I may on the X. axis is the
percentage of the Hop in cycle and once

again we see that vertical line separating
between stance an aerial phase and.

If you see a white van that white
been is representative of the point

in the cycle where there is.

That this little significance where
I am a was greater than zero.

So I am a greater than zero
of the joints were being

courted made that in order
to conserve leg length.

And as we're going through and looking at
our I am a results just to keep our eye

keep our eyes focused we're going to
look at stance in young two thousand and

nine it was shown that during
stance phases when leg length

was most likely it was most
affected by small changes in

the incl joint and also what we see
when we look at our free our control.

Condition is consistent with our
results consistent with deliberate Your

stance is when we're saying
that I am a greater than zero.

And when we see coordination occurring.

When we compare with their plan or
flexion block condition.

We're seeing an increase in I Am A So
there's an increase between

the free condition in the planar flexion
block condition for this average I made

that you and it's interesting to me is
the places where this increase occurred.

So if you look at the pre-condition vs the
planar flex and black condition you see

this kind of a difference right here
in the difference right here at

the beginning and at the end of our
stance phase which is where the plane or

flexion block condition was affecting
the ankle joint trajectory is where

you're really seeing that increase
in quarter nation occurring.

When we look at the source of
flexion block condition we

also saw a significant increase
in the average I am a.

And so we see the increase and
I am a and particularly at

the mid stance where the condition was
affecting the ankle trajectory again.

And so for a last constrained condition
looking at source of friction planar

flexion blocks we once again saw
that increased I am a value and

what's occurring is if you know
there's kind of it's almost as if

you are superimposing the plane or
flex and block condition on top of

the doors deflection lock condition and
so our result is what we see at the door.

So if I.
And

what condition you see that increase I
made both that to beginning the mid and

the end of stance because this is
the point in the cycle where our

constraint was actually
affecting our trajectory.

So in summary what is really learning here
is we are going through these graphs.

When we see that there's
an increase in the average I.M.A.

during the stance phase that is occurring
from the constrained conditions versus

the controlled condition and where this
and where this increase in court a nation

is occurring where I am is greater
than zero corresponds to the time

when the constraints were
affecting our hobby in cycle.

So looking back to I
have processed this and

what occurred in the during in relation to
the first prediction going that looking

across conditions we see which stated that
length of be conserved across conditions.

This is rejected for two of our conditions
when we look at their selection

condition in the planar flexion block
condition the length was not conserved in

comparison to the control condition or
the free condition but

when we look at the doors of
condition the length was considered.

So what's the difference
between these two.

Well what we're seeing is that there's
a dream cases where we're more or

less constraining the in cold so

such a high extreme that the leg
is not able to compensate anymore.

So that their selection planar flex and

block condition we have
lesser degrees of constraint.

So we're able to conserve that length.

Now looking across the hopping cycles and
looking at our second prediction for

I have bought this is where we stated that
the interest cycle joint variance will be

coordinated to conserve length
across the hobby in cycles and

we see that the length was conserved
from hop to hop within each condition.

So the joints quite a nation is
actually occurring in order to can

conserve this length so even though we're
not conserving across these conditions

when you're hopping over and over again
you're reaching for this new leg.

So what we're finding is that there's
a new goal for leg length when you

constrain the angle to the extreme that
is no longer able to overcome that block.

So when we look at our main trajectory
results we saw that the angle motion

was extremely limited for the plaintiff
and locked in the door selection

box conditions and when this case
the leg length was not conserved.

The system was unable to one unable
to overcome the limitations that had

been applied and so there was not there
was not able to conserve lightning.

But when we used our results from the use
C.M. analysis we see that across hops

we see an increase in court a nation
in order to conserve likely.

So we're seeing a cop and station strategy
that is occurring where we're now

trying to conserve a new leg length goal
versus that original eight length goal.

So one of the limitations for
the study was the fact that our F.O.

was not behaving the same for
each subjects.

So we had different
percentage of the blocked for

each condition that wasn't consistent
throughout the subjects one hope would be

to potentially repeat the study and get
that more consistent percentage block of

each condition and in hopes that that
would give us tighter Ken Matic results.

Another interesting thought that might
be would be to look in other joints.

What would happen when we construct the
knee or the hip or constrain the knee and

the hip at the same time or
the ankle in the knee at the same time

what we see similar results
are what compensations would

be occurring at the leg would there
still be conservation of leg length.

Well that's for the future but

to leave you on a note of
what we saw in this study and

to give you an idea of what you remember
and what to take out of this we have our

conclusion where we found that the system
was not always able to compensate.

The dearth of flexion blocked in
the plane or flexion blocked conditions

the constraints were too great for
the legs to compensate across conditions.

However when the system.

However the system concerns like
length across happy and cycles.

Even when the leg length
projector is changing.

We see that the joints are so

coordinated in order to
conserve a new leg length goal.

So what does this mean outside of
the research world how can this be applied

when you look at the patient
rehabilitation This suggests that we

should focus on rehabbing the whole limb
versus just doing rehabilitation for

an individual joint after
an injury has occurred.

Or a surgery has occurred.

And I thought it's important to understand
any associated compensation strategies

that are occurring at the joints.

So for restricting that ankle.

It's good to know what's occurring and
what is happening within the leg

to see what what effects we
are applying to our limb and

then in prosthetics kind of thinking
back to last week we saw that.

Were further prosthetic leg we're not
really reaching the same trajectory as

the control condition.

So if amputees are adopting
these different trajectory.

Then one suggest that we're finding
from this research is that they may be

coordinated in their joints in order
to stabilize a new leg length.

I would like to think the following people
for all their assistance in this projects

are Kinsey and Megan I've been great
helping me with all the stuff and

getting everything going in the lab
to complete this project and

also like to think Robert McDonald and
gives a Kotler for

their assistance in designing There's a
photo that came to be great fun as well as

fabricating that and then to Teresa snow
for her assistance in the civil analysis.

And I would also like to acknowledge
the National Science Foundation for

their assistance and
funding this research.

And question.

Thank you.

Yes there was

very few that a person I can.

Yes I can.

So this is the device.

OK So this is the device that was used and
so one of our big problems when we were

designing this device was making it so
that it could fit to multiple subjects and

in doing that we had to kind
of make some assumptions

in more or less make it so that it could
be adjusted to the different lengths

of foot the different heights in order to
have multiple people on multiple subjects

that were throughout the study and
so what we did was we had to.

More or
less we took up an aluminum plate and

we attached a stirrup and then double
actual angle double action angle joints.

To uprights and in doing this we were
able to slide then these uprights

to adjust to the different lengths
of the foot and so that was great.

We're able to over to accomplish that
task to fit to multiple people and

make it comfortable while
wearing However in doing this

design one of our weakest
points was right here.

So when people were hopping what we found
was that they were actually overcoming

this stainless steel joint and
they were bending our store up and

so the high forces that were occurring as
a result of Hoppe mean that usually aren't

seen during walking that the vices
typically would be used for overcoming in.

Actually been doing so
when we were trying to apply constraints.

The people were the subjects
were able to more or

less their different forces the different
weights that they had coming down adjusted

so the different percentages
of that occurred.

So.

We wanted to use that as a control
versus hopping with out and A.F.O.

in order to eliminate any effects that the
A.F.L. itself was adding onto the subject

as they were hoping for
the free condition.

No they weren't wearing a device
we use that in order to limit.

Like if between hopping normally and
hopping with the F.O..

Rather than comparing to hopping Normally
we would lose what effects were occurring

from the F.O.
if we can appear to the know it.

So the effects from the weight of the F.O.
if we had

compared to what was occurring without the
F.O. on we would have lost that effect.

We did we looked kind of did a comparison
before and after and statistically

there is a few differences but when you
kind of looked at the general trend.

It was more or
less following the same idea.

The main difference that we would see
was a shift into more player selection.

When you're wearing the If so
then when you weren't wearing the F.O.

and we kind of contributed that to
the weight of the A.F.L. point on the.

You know I didn't look particularly
at the dynamics of what

was happening in that playing but
the joint was fabricated so

that they wouldn't like there is
enough space for them to move.

And not collapse into
their into the joint.