cc >> James Reardon: All right,
good evening, everybody. Thanks a lot for coming here
to Chamberlain Hall at the University of Wisconsin campus,
Madison, Wisconsin. We are here tonight for a
presentation on the Physics of Yoga.
So, my name is Jim Reardon and in addition to being a physicist
here at the UW, I am a student of yoga.
I studied with Roger Eischens at Mound Street Yoga here in town.
And he studied in India, and I learned quite a lot
from studying with him. I'm not claiming to be a yoga
teacher tonight, but I would like to try to unpack some
mysteries of yoga that might not really be part of yoga.
But merely problem with communication.
I know that when I studied yoga, there were some words that yoga
teachers tended to use that I didn't really know what they
meant. And there are several of those
that I would like to write down here.
They would say things like balance.
They would insist that my yoga pose have integrity.
They would talk about in order to achieve integrity in the
pose, they would ask that I do work within the pose.
And then finally, the most mysterious of all, they would
ask me to get into a position which I was told was called
side warrior, which would be something like this.
Then I was told all right, now press your feet into the floor.
I didn't know what they meant. I still am not quite sure
that I know what they mean. But, what I have brought here
today, the things I was standing on are called force plates and
we will be able to measure the forces that the human body
has exerted upon it by the ground, during the course
of this lecture. We'll be able to measure, to
quantify the forces involved in yoga poses.
So hopefully we'll be able to give some meaning,
some physics meaning to balance, integrity of the pose,
work within the pose and the especially mysterious
press your feet into the floor.
Now that's just my personal list.
Now, if you have things that you've been told during yoga
class that you haven't really had explained properly, maybe
you can bring them up tonight and we can try to figure out
what the yoga teacher must have meant by mysterious phrases
that are used. All right.
So here we are in Chamberlain Hall, we have a bunch of props.
The first word that I'm going need to define here,
the first physics word is force. It turns out that it's actually
very hard to define that word force.
So I'm lucky that everybody, I hope, already knows
what a force feels like. If somebody comes up and exerts
a force on you, you know that someone
is exerting a force on you. Can I have a volunteer come down
from the audience and we'll see? All right.
Thanks a lot for coming down. So my name is Jim.
What's your name? >> Chloe.
>> Face the camera, Chloe, all right.
So, we are going to do a test to see if Chloe knows when someone
exerts a force on her. Are you ready?
>> Uh-huh. >> Close your eyes and then if
you feel someone exerting a force on you, if you feel a new
force being exerted on you, raise your left hand, all right?
We are going to start. At any time after now, a force
could be exerted, but don't do anything until you feel
a force and when you do, raise your left hand.
All right. So a force is just a push.
You can open your eyes. Everybody knows that, right?
So a force is just like a push. Let's do that one more time,
just to make sure, all right? Close your eyes, ok?
All right. So here we go.
Ready? All right.
So, did you feel a force? Yeah, when I say push,
I could mean pull. Push and pull are both types of
forces. It doesn't matter the direction
but you know automatically when someone exerts a force on you.
Great. Thanks a lot, Chloe.
Go back and sit down again. Physics of yoga.
Yoga is all about forces but yoga teachers tend to use that
word in a slightly unusual way. I'll draw your attention to this
bowling ball here. So, what are the forces that are
currently acting upon this bowling ball?
Well, if you can see the bowling ball is hanging from this wire.
We know, we who have gone bowling, bowling balls have some
weight. So I'm going to represent the
force of gravity by this arrow. Now the first thing that I want
you to take away from this lecture is that whether or not
you learn anything here tonight you are already experts in
physics because physics is the study of motion, and everyone
here already knows how to move. After all, you got here tonight.
So, you are already an expert in motion.
You already know how to manipulate forces, to get where
you want to go. What I hope to teach you tonight
is the language of arrows. Are there any other forces
acting on this bowling ball? There's the force of gravity
pointed downwards. Is there any other force acting
on the bowling ball? Yeah.
>> Tension. >> So, which direction does the
tension force act? >> Upward.
>> Upwards, that's the tension in the wire up here.
That's exactly right. I'm going to represent the
upward force of the wire with this arrow going up like this.
And so the rule of physics is that if an object is not moving,
then those arrows have to add up to nothing.
And when I say add up arrows, I mean head to tail, so that
means, let me take my arrows off, to add up these two arrows
I would put them head to tail would be like this.
So these two forces add up to zero.
And that has to be the case for any object which is not moving.
Now we could go further with this language of arrows.
If you study yoga deeply enough you'll eventually want to learn
a language called Sanskrit in which the most important
yoga texts are written. If you want to really dive into
physics you'll want to learn the language of math, in which
the most important physics texts are written.
Sanskrit is a language of great antiquity, being at least 5,000
years old. Math is a language of equal,
and perhaps greater antiquity. I don't know if anyone
has ever told you that math is a language, but it is.
If you take the trouble to learn it just like you take the
trouble to learn Sanskrit, you may find that it's
a lot easier to understand, in this case, physics.
So, there is our bowling ball.
Now let's go over here to our yoga master.
Here is a cut out of a person in --, also known as
Side Warrior Pose. No, this is, I'm sorry,
this is Extended Triangle Pose. Extended Triangle Pose,
my mistake. So, you know how to do this.
Has anyone ever done this particular pose before in yoga
class? So, it's not a very hard pose.
It does share with all the yoga poses the fact that you should
get into it and stay there for a little while.
And if you stay there for a little while, that means that
the forces upon you have to add up to nothing.
So what are the forces that act upon you when you are on this
pose? Well, there's the force of
gravity, just like the bowling ball that points downward.
And then there's a force on one leg that points upwards,
put this one over here.
And then you know you are bearing some weight on the other
leg, too, so that has to have an arrow representing an upwards
force on that. And then I need one more arrow
because in this pose you are resting your hand lightly
on the floor. So I need a fourth arrow to
represent the force upwards that the floor is exerting
on your hand. And so if you want to stay in
this pose, those arrows all have to add up to zero.
Now, do you have any control over this arrow?
The mass arrow. Is there anything you can do
about the length of that arrow? The length of this arrow is the
force of gravity upon you. That's equal to your weight.
So there's nothing you can do about that.
But these arrows, maybe there is something.
So what I would like to do, I would like to introduce you
to our force plates here. I need a volunteer to come down
and stand on these force plates. These force plates measure
force, so they'll measure the arrows that are pushing upwards
on your feet. So who can I get to come
down to volunteer to stand on the force plates?
All right. Yeah.
You could come down from in back, I will set up the force
plates so you can see their readout.
All right, great. What's your name?
>> Phil. >> All right.
Go ahead and face the audience Phil.
Are you a student here at the university?
>> Graduate student, yes. >> Have you ever studied yoga
before? >> No.
>> Great, here is your first lesson then.
The first thing I want you to do is stand on this plate right
here. This is plate number one.
Stand on it, you might want to face the screen there.
So, what I'm going to do, I'm going to start the force plate.
Hop off it for a second so people can see.
All right. Now go ahead and stand on the
force plate. And if you watch the screen, you
see there is this thing, and if you step off the force plate
again then that line changes. So let's take a bigger look at
that line. The first thing I'll do is get
rid of the old data. And the second thing I'll do
is blow up this scale here. So can you see that you stood
on that scale at about three seconds, a little bit after,
let me blow this up. A little bit after three
seconds. You stood on the scale and
it had been reading zero. Now, have you ever measured
force in Newton's before? >> Yes.
>> Where did you learn to do that?
>> In physics class. >> I wonder if anybody else
knows how to measure force in Newton's.
I don't want to make this more confusing than it has to be.
What I think I'll try, let me see if I can go here,
and let's see if we can change the axis values to pounds.
I know how to do that. I'll go here
and I'll go over there and then I'll go over here.
I'll do that. I'll go over here.
Because I think we might want to measure things, not in the
language of science, which is Newton's, but in the language of
everyday people which is pounds. So, you don't mind if I show
everybody your weight, do you? >> Go for it.
>> What we see is there was a force of about zero pounds and
then you stood on it and it was maybe a little bit more than 150
pounds and then you stepped off and it went back to zero,
more or less again. So this thing is basically like
a fancy bathroom scale. But, we've got two of them.
So let me call up the other one here.
And now what I want you to do in a moment is go ahead and when I
give you the signal stand on the first one and step backwards and
stand on the other one. So what I want to do is call up
a force here. Ok.
So, Phil, go ahead, when you are ready.
Stand on there. Let me get the start line going.
So we see from the graph here that's basically the same as
before. Now go ahead, step backwards
onto that other one. And we'll see what happens.
The other one is scale number two.
I'll stop now. And we'll get another graph
going here. Normal force two, run three.
All right. So here we have two graphs,
I'm sorry it's a lot of clicking in different windows right now.
And the scale one, which is this one, normal force one--
And the red one is the data that we want to look at right
now that shows that you are--
That got to be parallel force two.
We want that to be one, so we will try to tell it
to be one again, so we want it to do that.
All right. The front scale measured this,
it measured your body weight until you took the big step
backwards, and the other one which you are now standing on
measured your body weight. Let's see what happens
if you stand on both at once. Okay, go ahead and step off,
and I'll start taking data now. Go ahead and stand
on the back one. Now go ahead and take a step
forward, and stand on both of them at the same time,
and balance there. So now we have some serious
wiggles going on. Push forward so you get
onto the front one, stand there. And then stop again.
And stop, step off again. All right.
So let's try to figure out what those things on the screen mean.
So, it started out, we need a laser pointer.
I'm going to have to go back and get a laser pointer
from back here.
All right. So, you were standing on one
scale, which one are we looking at?
Let me get the extraneous data off, we don't need that anymore.
All right. You were standing on scale two,
which is the bottom one here. And then you took a step forward
so that you landed on the front scale, this time in the middle
your weight was equally on both, more or less.
And then you took another step forward and ended up on the
front scale up here. And all your weight was on that.
All right. Does that make sense?
>> Yes. >> All right.
We'll try to do something-- You can do this at home with
bathroom scales if you wanted. Let's see if your bathroom
scales can do this! What we also have here is what
we call the parallel force, so these scales measure not just
the up and down force but also the side to side force.
Let's see what that looks like. So if I took the side to side
force from one, I'll put that here.
And the side to side force from two and I'll put that down there
and let's see if we can try to figure that out.
So, they're in this part, at the beginning, when you are just
standing on one scale, neither of the side to side forces is
anything. And at the end when you are only
standing on scale number one, the side to side forces are also
zero. But in the middle they're not.
So in the middle the force that you are exerting on, well,
what leg is this, this is scale number one, this is your front
leg, is in the opposite direction than the force on your
rear leg. In other words, this line here
is above zero, and this line here is below zero.
And that turns out to be a very interesting thing for yoga.
All right. So, do you want to try some
yoga? >> Sure.
>> Okay, so let's see what happens.
Now I'm going to ask you to stand on both plates again.
All right. We have a live recording going
on of everything, let me remove some data so it's more clear.
All right. Looks like data studio has
beaten me and stopped itself so we have to start over again.
All right. So you are now standing
on a plate more or less symmetrically.
Face the audience perfectly symmetrically.
You're not bending to the left, not bending to the right
but you're standing straight up. The question is, which direction
should we put the arrows that are coming upwards from the
ground? So do you mind if we pin
some arrows to you? You wouldn't mind.
>> Go ahead. >> I do happen to have some
arrows over here. Just take them off old BKS.
All right. So, here is one arrow that
we are going to use to represent your weight.
You mind if we see if this velcro sticks to your sweater?
>> Sure. >> It doesn't.
You'll have to hold that somewhere.
A little bit lower down. We'll get into where the center
of mass is momentarily, so that's the force of gravity.
It has to be balanced by something, it's balanced by the
force that the ground is pushing up on you with, so there
have to be two arrows down here somewhere, so I'll start with
this foot. So we know there's got to be
an upward force to balance the downward force of gravity,
and the force plate tells me there has to be a sideways
force, which way does this arrow go?
That's the sideways force that the ground is exerting on Phil.
So how many people say the arrow should go this way?
How many say the arrow should go that way?
All right. Well, it looks like we have some
good physicists in the audience, that's right.
The arrow does, in fact, point inwards like this.
Now, what would happen if it didn't?
What would be an example of a surface that you can't have
an arrow do anything other than go up?
In other words, there's no friction because what
we are talking about after all is the force of friction.
Could you stand like this on ice?
>> No. >> You couldn't?
I think we still have some ice on the lake, you might want to
go out and try. And that's the secret that
we are going to get to over and over again here.
You could stand like this on ice but you would have to do
something with your muscles. It wouldn't change the shape
that you have right now, but it would feel completely different
because you can't rely on the force of friction to keep your
leg from sliding out sideways the way it would on ice.
However, you could, by tensing your abductors, by tensing some
muscles in your legs, you could keep it from happening.
Why don't you try? Let's see what happens?
I'll go ahead and take this back.
Let's see, now what would it feel like
if you wanted to stand on ice? What would you have to do?
>> Squeeze inward. >> Yeah, you personally would
have to squeeze your legs together instead of relying on
the ground to push you. Let's see if you can do that.
So I'm going to start, we are still going with the data here.
Go ahead and we're looking at this one here.
We're looking at the one with the parallel forces which is,
let me get rid of that, and let me get rid of this.
All right. We'll zoom out on there so we
have a parallel force it looks like of about 18 pounds in each
direction.
So we are still going, Phil, when you are ready.
Try to squeeze, imagine you're standing on ice,
squeeze your legs together, can you make the sideways component
of the force go to zero? Now, if I allowed you to
turn around and look, it would be easy.
And in yoga, a lot of this is imagination.
So can you just imagine that you are standing on ice?
Can you imagine you are not squeezing your legs as tightly
together as you could, but you are just imagining
that you are standing on ice. So, now I think you'll be able
to see here that he's doing a pretty good job, he's still got
a little bit of force, but it's a lot smaller than it was.
That's brilliant. So if you can see, I don't know
if you can see, but that force is very close within a pound or
two of zero. All right.
You've slacked off a little bit. There you go.
That's back really close to
zero. So, you could stand on ice
in that position. Is it tiring?
>> Yeah. >> It is tiring.
It works those muscles. You didn't pump any iron, you
didn't go for a run or anything, you just stood there.
But yet if you do the right things you can really get
a good workout. Thank you, Phil, for staying up
here for such a long time. Phil, a university student who
now knows a little bit about yoga.
Let's see what else we can do with these force plates.
Let's see what happens if we get someone who is actually
practiced in yoga to come up. So, do we have anyone here
who has actually studied yoga before?
All right. Chloe, you have, haven't you?
>> A little bit. >> A little bit.
Well, let's see what happens. So this time, are you
familiar with that phrase work within the pose?
>> Yes. >> So let's try that.
So what's your favorite pose that you could do
on two force plates? >> Probably what you were doing,
like what he was doing. I can't think of it.
>> It's one of the maybe front warriors or front lunges so you
come down with the knee bent. Let's see what happens when you
do that. So, let's see, we have there
and you can-- >> This?
>> Yep, so let me get-- Step off for a second.
Wwhat I'm going to do is take this stuff off the screen.
Let's see, I guess the easiest way for you to see what you're
doing is stand the way that you are, yeah, so let's
get run five off here.
And we're looking--
There's two questions that we want answer.
What happens to the normal force, in other words, when you
go into that pose, how is your weight distributed?
Do you have more weight on your front leg or do you have more
weight on your back leg. And then we'll see what happens
if you go from just standing and sort of the right shape to
standing in the correct yoga technique that you've been
taught. We'll see what kind of
difference that makes. All right.
So, I'm fiddling around, trying to remove all of this old data
from here and we'll put the normal force down there.
Oh, look, it did something, interesting.
And then we'll put the other normal force down there.
All right. So, when you are ready,
go ahead and step on the scale. And just hang out there in a
comfortable pose for a moment while I get rid of all this
stuff so it's easier to see what's going on.
All right. So that's you right now.
With a parallel force.
And this is statistics. How did that happen?
Computers. Oh, that's what happened.
All right. So get rid of that.
I'll get rid of this. All right.
And there we are with the normal force, and I didn't want that.
I said normal. I told you normal force.
Fascinating.
I'm sorry that physics, there is a certain amount of messing
about with physics and this type, usually computers have
something to do with it. I have to start all over again.
You can stay on, I think I have managed to arm wrestle this
computer into submission.
All right. So there is the parallel forces.
And the thing doesn't like it when I take that one away.
That's just too bad. All right.
We'll have to make another graph.
So we have the parallel forces going fine.
Okay, I think we've got it going there.
So what we are seeing here on the graph number four,
this one is, which weight do you have, which leg
do you have more weight on? So you already know a lot about
physics. Yes.
So you know if you come down and lean like that, you get into the
front warrior pose that you have more weight on the front leg and
less weight on the back leg so we can see there is twice as
much weight on the front leg, near 100 pounds as the back leg,
down closer to 50. Meanwhile you see the parallel
force on top, then on the front leg you've got about 20 pounds
going backwards, and on the back leg, you have about 20 pounds
going forwards. All right.
Now, what happens when you work within the pose?
>> Stabilize yourself. >> Exactly.
That's exactly, uh-huh. Yep.
So, I'm going to stop distracting you.
Do what you have to do. You might find it interesting
to look there. >> Okay.
So right now we learn a couple of things.
You could not do what you are doing now on ice.
>> No, I would do the splits. >> So you would do the splits,
exactly. That's very important.
I thought for a number of years when my yoga teacher was telling
me to force my feet into the ground, to press my feet into
the floor that what I ought to do is press them together like
I would have to do in order to stand on ice and I now know,
because I brought my yoga teacher in here to do it on the
force plates, that that's not true.
Now, meanwhile, if you do that again, you come back into the
neutral pose, and the weight goes--
That's the bottom graph. It shows you are almost equal
weight on the front and on the back, there is no real front and
back at this point. Now if you come down into the
warrior pose, yeah, more weight goes into the front leg.
What happens if you try to drive your back leg into the
floor, to press down on it? So it looks like you can.
Now, were you really pressing straight down on your back leg
without moving anything else? Let's see you do it again.
Or did you have to lean over a little bit backwards?
Oh, ok. See what you can do without
changing your shape. What work can you do
within the pose? And yeah, feel free to watch.
>> I'm trying to dig my heel into it.
>> Whatever you feel it takes to try to drive, only you cannot
actually lean backwards or move backwards or put both arms
backwards like this. Let's just make sure that
everyone understands what happens if you do those things.
If you are standing like that, and bring both arms like that
backwards, you can actually-- It's slipping?
Oh, no, okay. We better bring it
a little bit closer.
>> Both arms back? >> Uh-huh.
All right. So we have, what is it?
It's reversed, actually. So let's make sure we are clear
which one is the front one. If you lean all the way forward
onto the frong leg, so the orange is the front one.
Are you capable of keeping that front leg bent at 90 degrees,
say, like you are in warrior pose?
Can you get an equal amount of weight onto the back leg
by, say, moving your arms back or leaning backwards?
It looks like you just about can.
>> It's hard. >> It's hard to do that.
Yeah. All right.
So what did we learn? There is a point in the middle
where you were bringing your legs together and able to make
the parallel force go to zero, so you were able, you could do
that pose on ice if you wanted to, but that's not part of your
practice because when you are trying to do the practice
properly, then the force was quite different.
All right, splendid. Thanks a lot for helping us out
with that. >> No problem.
>> All right. So, there is two words
in physics that we have to use to talk about what one does
in yoga. So I'll write those two words
here.
I'm going to draw a line like this.
So this is the yoga part.
And here I'm going to try to translate the yoga part into the
physics language.
The first physics word that I need to use to explain what my
yoga teachers are telling me is that one, equilibrium.
And we have already covered that.
That means that all the arrows--
Add up to zero.
What happens if all the arrows don't add up to zero?
Well, what would be an example of an object that just had
one force on it? Yeah, Phil?
>> Falling bowling ball. >> A balling bowling ball.
That's right. If I were to cut this wire, that
would remove the tension force that is pulling up, and all
that would be left is the gravitational force,
the arrow pointing downwards. And since there's only one
arrow, the resultant arrow would be pointing downwards and
the resultant motion would be a downwards fall.
So, if you don't want to fall down, you have to make sure all
your arrows add up to zero and human beings are very good at
that, as long as it's not bar time.
You rarely see adults falling over and that means they are
maintaining equilibrium. But the other word
that we have to use if we want to say what is yoga,
is stability.
That's a very important physics concept which is also a very
important yoga concept. Let me quantify stability.
I need another volunteer from the audience.
All right, Phil. Thanks a lot for coming down.
Do you have good balance? >> I think so, yes.
>> All right. Let's find out.
So, what I want you to do is to stand on, let's say, force plate
number one. It doesn't matter, you can go
ahead and stand right now. And what I'm going to do
is put a graph on of the parallel force--
On that, which is actually not started yet.
So, go ahead and start taking data right now.
Parallel force run number ten, scale number one.
All right. So you're standing around,
not doing anything, but the parallel force still has
some fluctuations in it. You can, I suppose, turn and
face me and maybe see the fluctuations over there on the
screen. All right.
Let me zoom out a little bit, zoom in a little bit I mean
so that you can see better. And I want to see what happens
to those fluctuations if you now stand on one foot.
So, go ahead and keep your balance as best you can.
Ok. You notice that it's harder to
keep your balance exactly and you have to wobble around,
or you do wobble around a little bit more.
All right. But you are pretty stable,
you are pretty good, you are balancing successfully
on one foot. It's been 15 or 20 seconds now,
that's very good. Are you ready for another
challenge to your balance? You are in front of a bunch of
people, it could be tough, all right, because I'm going to ask
you to close your eyes and it's now 75 seconds, all right?
So close your eyes, that's it, come on, I know you can do it.
You're doing great. It's been 10 seconds now.
75 to 85 seconds. For the last challenge, the most
difficult balance trick of all, all right.
I want you to close your eyes and stand up on your tiptoes.
Close your eyes. No, you have to do it
on one foot, though. >> I have to get started,
though. >> All right.
It's now 100 seconds. You are doing great.
Keep it as long as you can. All right.
Excellent. From 100 to 110.
Now let's see how you did. So this is the trace of your,
of you standing on one foot, two feet, two feet then one foot
then one foot eyes closed and then finally one foot
eyes closed and on tiptoes.
So, this is, from 30 to 40, that is the time from 30 to 40
seconds when you were balanced on two feet.
So let's see if we can get a standard deviation for that.
If you don't know what standard deviation means,
then it's just the size of the fluctuations, it's the width of
that line, the width of that hash, if you will.
So, let's see if we can get a standard deviation out of this.
It's one of these things, is it this one?
No. Is it this one?
I don't want that one. Is it this one?
No. It's what?
>> Go to the arrow on the side of the sum button.
>> Standard deviation is what we want.
So the standard deviation of that was .03 pounds.
So that's a quantification of your balance.
.03 pounds. So now for this part here--
All right. So, is this automatically
tracking it when I move? 4 and 20, all right.
Then we'll go over here to the last one.
So for this part you are doing something really hard, you are
trying to balance on one foot, on tip toe with your eyes
closed, so the standard deviation is now a lot larger,
3.35. So how does that compare
to .03? So that's about 100 times, yeah.
So your balance is 100 times better when you are standing on
two feet with your eyes open than when you are balancing on
tiptoes with your eyes closed. We have some intermediate values
from 75 to 85. So that would be about
like here. So that was the,
just one foot eyes closed. All right.
So here for this part we have a standard deviation of 16,
so how is that? That's five times worse
than the first case, but it's a lot better than the second.
That's about 20 times better than the second.
All right. And then let's see, before that
the one foot eyes open, I think that was here.
And so it seems like you must have pretty good balance because
there wasn't much difference between--
Let's make sure that's true. Let's do this over again.
>> Ok. >> One more time.
You know what I want to you do, so let's do it more quickly.
Don't get on just yet.
So, we'll take data, all right? Go ahead and stand on it.
>> Two feet? >> Uh-huh, two feet.
Let me get the graph up. This is run 11,
parallel force one. So there you are.
Stand on one leg, now. That's at 20 seconds.
We'll hold you there for 10 seconds until we'll say 31.
Now when I give the signal, close your eyes.
Ready, and now, at 35 seconds you close your eyes.
That's fine. But we'll count it
as a fluctuation. All right.
And we'll see five seconds, go on the tip toe, right now.
At 50 seconds. All right.
So, let's see if we get the same answer for the statistics
out of this. So, at the beginning, two feet,
you stand on it that's here, we'll look at two feet from
there, standard deviation, .03 again.
That's the same as we got the first time.
So maybe I should believe that. Then you stood on one leg,
that happened at 21 seconds. So, we'll look at that
from 21 to about 30. And we got the same answer.
Look at that. Its .03 pounds again.
So you really do have just as good balance, it looks like,
on one leg as two. That's very rare.
Do you practice? >> No.
>> And then from 35 onwards, then that was the one,
that was what? One leg with eyes closed,
all right? So we had some fluctuation
right there and obviously, big fluctuation, and we got
.15 the first time, .12 the second time.
And then at 50 or so, a little before 50, that's when
you try to go on the tiptoes and that's really hard to do, not
many people can do that at all, so we have a standard deviation
that's about the same. So if I click on everything
there, we get a little better that time, but 1.9,
that's still a lot harder. Thanks a lot, Phil.
You can go sit down again.
So what we can measure here in the physics lab that is
important for yoga is, let me get an arrow here again.
So if you are standing on a force plate, you have
gravity going downwards. You have the force that the
force plate exerts on you going upwards.
But you, being a human being and not being a block of stone or
something are not capable of exerting a constant force.
So this arrow is constantly jiggling around.
And what we were measuring there on the screen was the side to
side motion of this arrow. So when anybody stands, no one,
no one is capable of having a completely constant force.
Everybody wobbles a little bit. And what we can measure and
quantify is the amount of that wobble.
So, someone who has good stability--
Where's my pen? It's over here.
So good stability.
I'm going to have to remove-- Anyone want a cheap
bowling ball? So it's not real good
for bowling, because it has this hook in it.
Going once, going twice-- All right.
I guess we get to keep our bowling ball then.
So good stability, let me write this slightly more neatly.
So in order to be stable you have to minimize the fluctuation
of the ground forces. So that's what the yoga teacher,
let's go back to our list here, so I can draw this talk
to a close. The balance, when a yoga teacher
talks about good balance, I think what they mean is they
want you to minimize the fluctuations that are in your
ground forces. Now, is it possible
that you can do that? And the answer is
it turns out to be yes. Now I don't claim to be a yoga
teacher, but I think I know how to do that.
Now, I'm not sure if we can actually do this live.
You might not be able to do this live because I am not a yoga
teacher. But let's see what happens.
So, can we get someone up who wants to see if they can improve
their balance in realtime by doing yoga work within the pose?
All right. Chloe, thanks a lot for helping
us out so much. All right.
Now, go ahead and turn and face the cameras a bit.
Is this the sort of thing that your yoga teacher says?
>> Yeah. >> What sorts of thing does your
yoga teacher say? >> She says just to stabilize
yourself, and the breathing is so important.
That helps the stability, too. >> Mm-hmm, breathing.
>> Constant breath, constant kind of motion within your body.
>> So you are emphasizing your breathing.
>> Yep. >> All right.
Well, do you mind if we see if that makes a difference?
>> Sure. >> So I don't know if it will,
and I realize it's an artificial environment for doing yoga,
and it's not the most relaxing environment in which to do yoga,
but let's go ahead and give it a try.
I remember we had a little problem with the force plates
being too far apart, we'll move them a little bit closer.
All right. So do you know what pose
you want to do for us tonight to practice, to show off
the breathing as a method of stabilizing?
>> Yeah, I'll just do the same. >> Whatever your favorite is.
>> Actually, I might do warrior 3, the forward one.
>> Really, yeah. You're going to do Warrior 3.
That's a one-legged pose. >> I'll try it.
>> Wow, okay, great. This will be a great test,
because it's not that easy to balance on one leg.
>> The first time, really. >> I'm not going to put any data
on the screen. So how long would be reasonable
to ask you to just stand like that?
And then how long would be reasonable to ask you to
practice the yoga in that pose? Like 30 seconds for each?
>> Sure. >> All right.
>> Just standing? >> So, I'll ask you to stand
for, let's cut it short so you don't get tired.
15 seconds starting right, now. 30 seconds.
So at this point, are you just standing?
Or is that the yoga? >> I'm standing in a pose.
>> But you are not doing the careful breathing stuff.
Perfect, all right. I'm going to ask you to start
the breathing stuff in five seconds.
So, when you are ready, start it and just hold it as long as you
want, at least 15 seconds. Start it now.
Okay, all right. So let's see what happened.
Now how did you feel? Let me first ask you how you
felt doing first, just standing in that position and then
second, doing the actual yoga techniques of relaxation through
breathing. How did you feel?
>> When I was breathing I would focus on a spot in the ground
and the breathing was keeping me more stable.
>> Did you actually feel more stable?
>> I did, yes. >> You did.
So let's see. Well, what you feel
is very important. And I don't want to claim that
the machine is right and that you are not.
So what you feel is very important.
I'm trying to use machines as a way people can communicate
with each other. Because I can take this computer
and show it to someone else, and have somebody else stand
and we can compare it. It's harder, I have found,
to communicate feelings. All right.
Let's look at what we had here. So you were run number 12,
and on force plate number one. We'll look at the parallel
force. We get this stuff, and so it was
at about 30 seconds that I asked you to just stand there.
Well, we don't know, we don't know.
So I'm going to take from 30 to about 50.
Take that 20-second period. And we'll look at the
fluctuations, the technical name is the standard deviation.
So this is like the wobble. It was .03 standing on one leg
in that crazy pose, then your balance is still
really good. All right.
Now let's see how that compares with the next.
Starting at 60, so this, let's see what yoga does.
From 60 to, we'll say 80. And then we have the same.
All right. So let's blow this up
on the scale a little bit. So we can make sure that it
looks the same to our eyes, too.
Is there any obvious change at 60 seconds, that's when you
started doing the yoga. I didn't actually see any change
at that point. All right.
So, it's inconclusive. It doesn't show a change
one way or the other. So, an inconclusive experiment
doesn't mean it's a wrong experiment, but we didn't
actually learn anything. >> The breathing might be
a personal preference, a personal thing.
>> So yeah, the only thing I know of that we might do
is ask for you to try something more challenging.
>> Okay. >> Well, I don't know.
I don't want to challenge you too much.
What would be-- >> I have trouble putting
my arms up in that pose, I can try that.
Compared to a different arm pose.
>> Would you be willing to try that?
Great. >> Should I do the first 30
this is what I'm comfortable in and then going up
in the second 30? >> What I want to see
is what yoga does. So if you can try and stand in a
difficult pose without doing the yoga stuff and we'll take data
on that, and then allow you to prepare the proper way,
the way you are used to, the way that makes you feel
more relaxed, and we'll see what that does.
Tell me when you're ready. >> Okay, ready.
>> All right. So that's the, that's the
difficult challenge, that is quite a challenging pose.
I'm going to ask you to hold that for 10 more seconds.
Five more seconds. All right.
You can go ahead and step off. All right.
Now, are you ready to do what you need to do
to get into that pose? The way that you are comfortable
with? Using the breathing and then let
me know when you are there. >> Okay.
All right. >> We are at 48 seconds now.
Just keep breathing.
Okay, and that's 15 seconds through that.
( inaudible ) Well, I wonder why.
So, we'll get rid of run 12, we don't need that anymore.
So here was the yoga stuff was from 48 to 1:03,
that's about there. All right.
Again, that's .03 standard deviation, it might be just a
limit of resolution of this device.
And then the first part was from 10 to about 25.
All right, so I can't tell a difference.
I cannot tell a difference in that pose.
Well, we gave it the good scientific try and that's the
sort of thing we do here at the yoga research labs we have here,
we try to figure out what exactly is happening when people
go into yoga, so we can communicate it, because it's
difficult sometimes to communicate a feeling you get.
All right. Chloe, thank you very much
for helping us out. Well, I see that I have just
about run out of time with what I wanted to say.
Let me just finish by saying that people who have good
balance or when the yoga teacher asks you to balance in the pose,
you can think of that, you can measure it, if you had
a force plate as minimizing the fluctuations in the ground
forces. When a yoga teacher says
maintain integrity of the pose, that also requires
this to happen. I haven't had time to talk about
integrity of the pose, but that means that you are not moving
in the middle somewhere, that if you stand in that pose that you
demonstrated for us, this outstretched pose, if someone
were to press sideways on your hand then your whole body
would swing around. That would mean that you have
integrity, the whole thing is connected.
And work within the pose, I think maybe Phil did that a
little bit for us, when you are capable of standing in a pose
and then tensing a lot of muscles but not actually moving.
So you can't tell just by looking at someone whether they
are standing with their legs relaxed as mine are now, or
their legs tensed with all the muscles tensed as much as
possible, which is what I'm doing now.
The outside form doesn't change very much so you can work within
the pose, maintaining your equilibrium without actually
moving. By doing good work within the
pose you improve your stability. Finally, the last one,
press your feet into the floor, apparently that depends on the
yoga teacher. I've had people come up on the
force plates and when I tell them to do what your yoga
teacher tells you to do, to press your feet into the floor,
they make the sideways forces go to zero, as if they are
standing on ice. Others don't.
I conclude there is not one uniform standard among all yoga
teachers for what they want you to accomplish in the pose.
All right. Well that's all we have time
for tonight. I'm Jim Reardon, this has been
the physics of yoga. Thanks a lot for coming to
Chamberlain Hall on this evening to try to do some laboratory
work on yoga. Good luck in your practice, good
luck in your physics classes.