WEBVTT

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🎵 [music] 🎵

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KIDS: Our World!

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EVAN: Ninety Eight, Ninety
nine, One hundred. Whew!

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I do my best to stay fit.

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We all know that exercise is an
important part of a healthy
lifestyle,

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but did you know that exercise
is even more

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important when youíre training
to be an astronaut?

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Other than eating and drinking,
what do you think

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NASA astronauts to stay
healthy?

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KIDS 1: Hmm...Experiments!

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KIDS 2: I know, I know. Is it
Moon walking?

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EVAN: Exercise! You see
floating in space is a lot of
fun,

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but spending time in space
causes changes in the body

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that arenít good when the
astronaut returns to Earth.

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You see on Earth, our bodies
work against gravity.

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Gravity is the force that pulls
you to the ground.

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When you stand up, you have to
lift the weight of your

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body and carry that weight
wherever you go. The muscles in
your legs,

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back, and neck have to work
against gravity with every step
you take.

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Even when you take a rest after
playing with your friends,

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your muscles are still working
against gravity!

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Your bones get a workout too.

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Your skeleton supports your
muscles and protects your
insides.

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When you stand up, walk, or run
around, your bones are carrying
your bodyís weight Ė

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this kind of work keeps your
bones strong.

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Gravity gives your heart a
workout too.

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When you are standing up on
Earth, gravity pulls the blood
down toward your feet,

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so your heart works hard
against gravity to pump the

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blood up to your brain and to
keep the blood moving from

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your feet back up to your
heart.

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But in space all of these
things change. You want to find
out more?

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Letís visit a friend over at
NASAís Johnson Space Center.

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Dr Kjell Lindgren helps keep
our astronauts healthy and fit
for travel!

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DR. LINDGREN: Weightlessness
looks like a lot of fun.

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The astronauts are floating
their tools and their food is
also floating around.

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But itís also hard on the body
as well. The heart

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doesnít have to work as hard
because youíre not standing up.

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When you stand up on Earth the
blood is pulled down by gravity

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and the heart and the muscles
have to work to keep the

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blood moving back up to the
heart and up to the brain.

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So the heart doesnít have to
work as hard in space.

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Your bones and your muscles
also donít have to work as

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hard because youíre not
standing up, your not having to
work against gravity.

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So those can weaken, and so you
can lose bone mass

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and your muscles can become
smaller.

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Itís very similar to someone
just laying in bed all the
time.

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Scientists actually use that as
a model or a way to

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demonstrate the effects of
weightlessness.

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We have people lay in bed for
long periods of time and we

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look at how their bones weaken
and their muscles

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and their hearts weaken as a
result. Some of these tests
last up to 90 days.

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EVAN: In bed for a 90 days!
Thatís no fun.

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DR. LINDGREN: So we use
exercise in space. The
astronauts exercise

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to help keep their bones
healthy and their muscles

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healthy and their hearts
healthy.

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EVAN: Thanks for sharing all
this fascinating information
with us.

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Astronauts can inspire you to
make physical fitness a part of
your life too.

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Iím even more motivated to work
out than before.

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Come on Globey, Iíll race ya!

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? [music] ?

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KIDS: Our World!