What makes muscles grow? - Jeffrey Siegel

21,898,498 views ใƒป 2015-11-03

TED-Ed


ืื ื ืœื—ืฅ ืคืขืžื™ื™ื ืขืœ ื”ื›ืชื•ื‘ื™ื•ืช ื‘ืื ื’ืœื™ืช ืœืžื˜ื” ื›ื“ื™ ืœื”ืคืขื™ืœ ืืช ื”ืกืจื˜ื•ืŸ.

ืชืจื’ื•ื: Ido Dekkers ืขืจื™ื›ื”: Tal Dekkers
00:06
Muscles.
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ืฉืจื™ืจื™ื.
00:08
We have over 600 of them.
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ื™ืฉ ืœื ื• ื™ื•ืชืจ ืž 600 ืžื”ื.
00:10
They make up between 1/3 and 1/2 of our body weight,
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ื”ื ืžื”ื•ื•ื™ื ื‘ื™ืŸ 1/3 ืœ 1/2 ืžืžืฉืงืœ ื”ื’ื•ืฃ ืฉืœื ื•,
00:14
and along with connective tissue,
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ื•ื™ื—ื“ ืขื ืจืงืžื•ืช ื”ื—ื™ื‘ื•ืจ,
00:16
they bind us together, hold us up, and help us move.
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ื”ื ืžื—ื‘ืจื™ื ืื•ืชื ื•, ืžื—ื–ื™ืงื™ื ืื•ืชื ื•, ื•ืขื•ื–ืจื™ื ืœื ื• ืœื ื•ืข.
00:20
And whether or not body building is your hobby,
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ื•ืื ื‘ื ื™ื™ืช ืฉืจื™ืจื™ื ื”ื™ื ืชื—ื‘ื™ื‘ ืฉืœื›ื ืื• ืœื,
00:22
muscles need your constant attention
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ืฉืจื™ืจื™ื ืฆืจื™ื›ื™ื ืชืฉื•ืžืช ืœื‘ ืžืชืžื“ืช
00:25
because the way you treat them on a daily basis
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ืžืคื ื™ ืฉื”ื“ืจืš ื‘ื” ืืชื ืžื˜ืคืœื™ื ื‘ื”ื ืขืœ ื‘ืกื™ืก ื™ื•ื ื™ื•ืžื™
00:27
determines whether they will wither or grow.
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ืงื•ื‘ืข ืื ื”ื ื™ืงืžืœื• ืื• ื™ื’ื“ืœื•.
00:31
Say you're standing in front of a door, ready to pull it open.
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ื ื’ื™ื“ ืฉืืชื ืขื•ืžื“ื™ื ืœืคื ื™ ื”ื“ืœืช, ืžื•ื›ื ื™ื ืœืคืชื•ื— ืื•ืชื”.
00:34
Your brain and muscles are perfectly poised to help you achieve this goal.
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ื”ืžื•ื— ืฉืœื›ื ื•ื”ืฉืจื™ืจื™ื ืžื™ื•ืขื“ื™ื ื‘ืฆื•ืจื” ืžื•ืฉืœืžืช ืœื”ืฉื™ื’ ืืช ื”ืžื˜ืจื” ื”ื–ื•.
00:39
First, your brain sends a signal to motor neurons inside your arm.
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ืจืืฉื™ืช, ื”ืžื•ื— ืฉืœื›ื ืฉื•ืœื— ืื•ืช ืœื ื™ื•ืจื•ื ื™ื ืžื•ื˜ื•ืจื™ื™ื ื‘ืชื•ืš ื”ื–ืจื•ืข.
00:43
When they receive this message, they fire,
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ื›ืฉื”ื ืžืงื‘ืœื™ื ืืช ื”ืžืกืจ, ื”ื ื™ื•ืจื™ื,
00:45
causing muscles to contract and relax,
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ืžื” ืฉื’ื•ืจื ืœืฉืจื™ืจื™ื ืœื”ืชื›ื•ื•ืฅ ื•ืœื”ืจืคื•ืช,
00:49
which pull on the bones in your arm and generate the needed movement.
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ืžื” ืฉืžื•ืฉืš ืืช ื”ืขืฆืžื•ืช ื‘ื–ืจื•ืข ืฉืœื›ื ื•ืžื™ื™ืฆืจ ืืช ื”ืชื ื•ืขื” ื”ืจืฆื•ื™ื”.
00:53
The bigger the challenge becomes, the bigger the brain's signal grows,
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ื›ื›ืœ ืฉื”ืืชื’ืจ ื’ื“ื•ืœ ื™ื•ืชืจ, ื”ืื•ืช ืžื”ืžื•ื— ื’ื“ืœ,
00:57
and the more motor units it rallies to help you achieve your task.
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ื•ื”ื•ื ืžืกืชืžืš ืขืœ ื™ื•ืชืจ ื™ื—ื™ื“ื•ืช ืžื•ื˜ื•ืจื™ื•ืช ื›ื“ื™ ืœื”ืฉื™ื’ ืืช ื”ืžื˜ืจื”.
01:01
But what if the door is made of solid iron?
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ืื‘ืœ ืžื” ืื ื”ื“ืœืช ืขืฉื•ื™ื™ื” ืžื‘ืจื–ืœ ืžื•ืฆืง?
01:04
At this point, your arm muscles alone
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ื‘ื ืงื•ื“ื” ื–ื•, ืฉืจื™ืจื™ ื”ื™ื“ ืฉืœื›ื ื‘ืœื‘ื“
01:06
won't be able to generate enough tension to pull it open,
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ืœื ื™ื”ื™ื• ืžืกื•ื’ืœื™ื ืœื™ื™ืฆืจ ืขื•ืžืก ืžืกืคื™ืง ื›ื“ื™ ืœืคืชื•ื— ืื•ืชื”,
01:10
so your brain appeals to other muscles for help.
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ืื– ื”ืžื•ื— ืฉืœื›ื ืคื•ื ื” ืœืฉืจื™ืจื™ื ืื—ืจื™ื ืœืขื–ื•ืจ.
01:13
You plant your feet, tighten your belly, and tense your back,
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ืืชื ื ื•ื˜ืขื™ื ืืช ื”ืจื’ืœื™ื™ื ืฉืœื›ื, ืžื›ื•ื•ืฆื™ื ืืช ื”ื‘ื˜ืŸ, ื•ืžืงืฉื™ื—ื™ื ืืช ื”ื’ื‘ ืฉืœื›ื,
01:17
generating enough force to yank it open.
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ืžื™ื™ืฆืจื™ื ืžืกืคื™ืง ื›ื•ื— ืœืคืชื•ื— ืื•ืชื”.
01:20
Your nervous system has just leveraged the resources you already have,
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ืžืขืจื›ืช ื”ืขืฆื‘ื™ื ืฉืœื›ื ื”ืฉืชืžืฉื” ื‘ืžืฉืื‘ื™ื ืฉื›ื‘ืจ ื™ืฉ ืœื›ื,
01:24
other muscles,
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ืฉืจื™ืจื™ื ืื—ืจื™ื,
01:26
to meet the demand.
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ื›ื“ื™ ืœืขืžื•ื“ ื‘ื‘ื™ืงื•ืฉ.
01:27
While all this is happening,
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ื‘ืขื•ื“ ื›ืœ ื–ื” ืžืชืจื—ืฉ,
01:28
your muscle fibers undergo another kind of cellular change.
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ืกื™ื‘ื™ ื”ืฉืจื™ืจื™ื ืฉืœื›ื ืขื•ื‘ืจื™ื ืกื•ื’ ื ื•ืกืฃ ืฉืœ ืฉื™ื ื•ื™ ืชืื™.
01:32
As you expose them to stress, they experience microscopic damage,
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ื›ืฉืืชื ื—ื•ืฉืคื™ื ืื•ืชื ืœืœื—ืฅ, ื”ื ื—ื•ื•ื™ื ื ื–ืง ืžื™ืงืจื•ืกืงื•ืคื™,
01:37
which, in this context, is a good thing.
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ืฉื‘ื”ืงืฉืจ ื”ื–ื”, ื”ื•ื ื“ื‘ืจ ื˜ื•ื‘.
01:40
In response, the injured cells release inflammatory molecules called cytokines
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ื‘ืชื’ื•ื‘ื”, ื”ืชืื™ื ื”ืคื’ื•ืขื™ื ืžืฉื—ืจืจื™ื ืžื•ืœืงื•ืœื•ืช ื“ืœืงืชื™ื•ืช ืฉื ืงืจืื•ืช ืฆื™ื˜ื•ืงื™ื ื™ื
01:45
that activate the immune system to repair the injury.
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ืฉืžืคืขื™ืœื™ื ืืช ืžืขืจื›ืช ื”ื—ื™ืกื•ืŸ ื›ื“ื™ ืœืชืงืŸ ืืช ื”ื ื–ืง.
01:50
This is when the muscle-building magic happens.
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ืื– ืงืกื ื‘ื ื™ื™ืช ื”ืฉืจื™ืจื™ื ืžืชืจื—ืฉ.
01:53
The greater the damage to the muscle tissue,
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ื›ื›ืœ ืฉื”ื ื–ืง ื’ื“ื•ืœ ื™ื•ืชืจ ืœืจืงืžืช ื”ืฉืจื™ืจ,
01:55
the more your body will need to repair itself.
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ื”ื’ื•ืฃ ืฉืœื›ื ื™ืฆื˜ืจืš ื™ื•ืชืจ ื›ืœ ืœืชืงืŸ ืืช ืขืฆืžื•.
01:59
The resulting cycle of damage and repair
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ื”ืžื—ื–ื•ืจ ืฉื ื•ืฆืจ ืฉืœ ื ื–ืง ื•ืชื™ืงื•ืŸ
02:01
eventually makes muscles bigger and stronger
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ืœื‘ืกื•ืฃ ืขื•ืฉื” ืืช ื”ืฉืจื™ืจื™ื ื’ื“ื•ืœื™ื ื•ื—ื–ืงื™ื ื™ื•ืชืจ
02:04
as they adapt to progressively greater demands.
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ื›ืฉื”ื ืžืชืื™ืžื™ื ื‘ื”ื“ืจื’ืชื™ื•ืช ืœื“ืจื™ืฉื•ืช ื”ื’ื•ื‘ืจื•ืช.
02:08
Since our bodies have already adapted to most everyday activities,
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ืžืื—ืจ ื•ื”ื’ื•ืฃ ืฉืœื ื• ื›ื‘ืจ ืžื•ืชืื ืœืจื•ื‘ ื”ืคืขื™ืœื•ื™ื•ืช ื”ื™ื•ื ื™ื•ืžื™ื•ืช,
02:11
those generally don't produce enough stress
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ื”ืŸ ื‘ื“ืจืš ื›ืœืœ ืœื ืžื™ื™ืฆืจื•ืช ืžืกืคื™ืง ืขื•ืžืก
02:14
to stimulate new muscle growth.
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ื›ื“ื™ ืœืขื•ื“ื“ ื’ื“ื™ืœืช ืฉืจื™ืจื™ื ื—ื“ืฉื”.
02:17
So, to build new muscle, a process called hypertrophy,
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ืื–, ื›ื“ื™ ืœื‘ื ื•ืช ืฉืจื™ืจื™ื ื—ื“ืฉื™ื, ืชื”ืœื™ืš ืฉื ืงืจื ื”ื™ืคืจื˜ืจื•ืคื™,
02:20
our cells need to be exposed to higher workloads than they are used to.
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ื”ืชืื™ื ืฉืœื ื• ืฆืจื™ื›ื™ื ืœื”ื™ื•ืช ื—ืฉื•ืคื™ื ืœืขื•ืžืกื™ื ื’ื‘ื•ื”ื™ื ื™ื•ืชืจ ืžืฉื”ื ืจื’ื™ืœื™ื ืืœื™ื”ื.
02:25
In fact, if you don't continuously expose your muscles to some resistance,
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ืœืžืขืฉื”, ืื ืœื ื”ื™ื™ืชื ื—ื•ืฉืคื™ื ืืช ื”ืฉืจื™ืจื™ื ืœืฉื›ื ื‘ืขืงื‘ื™ื•ืช ืœืžืขื˜ ื”ืชื ื’ื“ื•ืช,
02:29
they will shrink,
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ื”ื ื™ืชื›ื•ื•ืฆื•,
02:31
a process known as muscular atrophy.
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ืชื”ืœื™ืš ืฉื™ื“ื•ืข ื›ื ื™ื•ื•ืŸ ืฉืจื™ืจื™ื.
02:34
In contrast, exposing the muscle to a high-degree of tension,
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ื‘ื ื™ื’ื•ื“, ื—ืฉื™ืคืช ื”ืฉืจื™ืจื™ื ืœืจืžื” ื’ื‘ื•ื”ื” ืฉืœ ืœื—ืฅ,
02:37
especially while the muscle is lengthening,
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ื‘ืขื™ืงืจ ื›ืฉื”ืฉืจื™ืจ ืžืชืืจืš,
02:40
also called an eccentric contraction,
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ืžื” ืฉื™ื“ื•ืข ื’ื ื›ื”ืชื›ื•ื•ืฆื•ืช ืืงืกื ื˜ืจื™ืช,
02:42
generates effective conditions for new growth.
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ื™ื•ืฆืจืช ืžืฆื‘ ืืคืงื˜ื™ื‘ื™ ืœืฆืžื™ื—ื” ื—ื“ืฉื”.
02:46
However, muscles rely on more than just activity to grow.
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ืขื ื–ืืช, ืฉืจื™ืจื™ื ืžืกืชืžื›ื™ื ืขืœ ื™ื•ืชืจ ืžืจืง ืคืขื™ืœื•ืช ืœื’ื“ื™ืœื”.
02:50
Without proper nutrition, hormones, and rest,
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ื‘ืœื™ ื”ื–ื ื” ื ืื•ืชื”, ื”ื•ืจืžื•ื ื™ื, ื•ืžื ื•ื—ื”,
02:53
your body would never be able to repair damaged muscle fibers.
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ื”ื’ื•ืฃ ืฉืœื›ื ืœืขื•ืœื ืœื ื™ื”ื™ื” ืžืกื•ื’ืœ ืœืชืงืŸ ืืช ื”ื ื–ืง ืœืกื™ื‘ื™ ื”ืฉืจื™ืจื™ื.
02:56
Protein in our diet preserves muscle mass
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ื—ืœื‘ื•ื ื™ื ื‘ืชื–ื•ื ื” ืฉืœื ื• ืฉื•ืžืจื™ื ืขืœ ืžืกืช ื”ืฉืจื™ืจื™ื
02:59
by providing the building blocks for new tissue
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ืขืœ ื™ื“ื™ ืืกืคืงืช ืื‘ื ื™ ื”ื‘ื ื™ื™ืŸ ืœืจืงืžื” ื—ื“ืฉื”
03:02
in the form of amino acids.
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ื‘ืฆื•ืจื” ืฉืœ ื—ื•ืžืฆื•ืช ืืžื™ื ื•.
03:04
Adequate protein intake, along with naturally occurring hormones,
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ืฆืจื™ื›ืช ื—ืœื‘ื•ื ื™ื ืžืกืคื™ืงื”, ื™ื—ื“ ืขื ื”ื•ืจืžื•ื ื™ ื’ื“ื™ืœื” ืฉืžื•ืคื™ืขื™ื ื‘ื˜ื‘ืขื™ื•ืช,
03:08
like insulin-like growth factor and testosterone,
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ื›ืžื• ืคืืงื˜ื•ืจ ื’ื“ื™ืœื” ื“ืžื•ื™ ืื™ื ืกื•ืœื™ืŸ ื•ื˜ืกื˜ื•ืกื˜ืจื•ืŸ,
03:11
help shift the body into a state where tissue is repaired and grown.
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ืขื•ื–ืจื™ื ืœื”ืกื™ื˜ ืืช ื”ื’ื•ืฃ ืœืžืฆื‘ ื‘ื• ื”ืจืงืžื” ืžืชื•ืงื ืช ื•ื’ื“ืœื”.
03:16
This vital repair process mainly occurs when we're resting,
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ื”ืชื™ืงื•ืŸ ื”ื—ื™ื•ื ื™ ื”ื–ื” ืžืชืจื—ืฉ ื‘ืขื™ืงืจ ื›ืฉืื ื—ื ื• ื ื—ื™ื,
03:19
especially at night while sleeping.
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ื‘ืขื™ืงืจ ื‘ืœื™ืœื” ื›ืฉืื ื—ื ื• ื™ืฉื ื™ื.
03:22
Gender and age affect this repair mechanism,
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ืžื™ืŸ ื•ื’ื™ืœ ืžืฉืคื™ืขื™ื ืขืœ ืžื ื’ื ื•ืŸ ื”ืชื™ืงื•ืŸ,
03:25
which is why young men with more testosterone
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ืœื›ืŸ ืœื’ื‘ืจ ืฆืขื™ืจ ืขื ื™ื•ืชืจ ื˜ืกื˜ื•ืกื˜ืจื•ืŸ
03:27
have a leg up in the muscle building game.
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ื™ืฉ ื™ืชืจื•ืŸ ื‘ืžืฉื—ืง ื‘ื ื™ื™ืช ื”ืฉืจื™ืจื™ื.
03:30
Genetic factors also play a role in one's ability to grow muscle.
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ื’ื•ืจืžื™ื ื’ื ื˜ื™ื™ื ื’ื ืžืฉื—ืงื™ื ืชืคืงื™ื“ ื‘ื™ื›ื•ืœืช ืฉืœ ืื“ื ืœื’ื“ืœ ืฉืจื™ืจ.
03:34
Some people have more robust immune reactions to muscle damage,
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ืœื›ืžื” ืื ืฉื™ื ื™ืฉ ืชื’ื•ื‘ื” ื—ื™ืกื•ื ื™ืช ืžื•ื’ื‘ืจืช ื™ื•ืชืจ ืœื ื–ืง ื‘ืฉืจื™ืจ,
03:38
and are better able to repair and replace damaged muscle fibers,
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ื•ืžืกื•ื’ืœื™ื ืœืชืงืŸ ื•ืœื”ื—ืœื™ืฃ ื˜ื•ื‘ ื™ื•ืชืจ ืกื™ื‘ื™ ืฉืจื™ืจื™ื ืคื’ื•ืžื™ื,
03:42
increasing their muscle-building potential.
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ื•ืžื’ื“ื™ืœื™ื ืืช ืคื•ื˜ื ืฆื™ืืœ ื‘ื ื™ื™ืช ื”ืฉืจื™ืจื™ื ืฉืœื”ื.
03:44
The body responds to the demands you place on it.
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ื”ื’ื•ืฃ ืžื’ื™ื‘ ืœื“ืจื™ืฉื•ืช ืฉืืชื ืžืฆื™ื‘ื™ื ืœื•.
03:47
If you tear your muscles up, eat right, rest and repeat,
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ืื ืชืงืจืขื• ืืช ื”ืฉืจื™ืจื™ื ืฉืœื›ื, ืชืื›ืœื• ื ื›ื•ืŸ, ืชื ื•ื—ื• ื•ืชื—ื–ืจื• ืขืœ ื–ื”,
03:52
you'll create the conditions to make your muscles as big and strong as possible.
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ืชื™ืฆืจื• ืืช ื”ืžืฆื‘ ืœื’ืจื•ื ืœืฉืจื™ืจื™ื ืฉืœื›ื ืœื”ื™ื•ืช ื’ื“ื•ืœื™ื ื•ื—ื–ืงื™ื ื›ื›ืœ ื”ืืคืฉืจ.
03:57
It is with muscles as it is with life:
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ืขื ื”ืฉืจื™ืจื™ื ื›ืžื• ืขื ื”ื—ื™ื™ื:
03:59
Meaningful growth requires challenge and stress.
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ื’ื“ื™ืœื” ืžืฉืžืขื•ืชื™ืช ื“ื•ืจืฉืช ืืชื’ืจ ื•ืœื—ืฅ.
ืขืœ ืืชืจ ื–ื”

ืืชืจ ื–ื” ื™ืฆื™ื’ ื‘ืคื ื™ื›ื ืกืจื˜ื•ื ื™ YouTube ื”ืžื•ืขื™ืœื™ื ืœืœื™ืžื•ื“ ืื ื’ืœื™ืช. ืชื•ื›ืœื• ืœืจืื•ืช ืฉื™ืขื•ืจื™ ืื ื’ืœื™ืช ื”ืžื•ืขื‘ืจื™ื ืขืœ ื™ื“ื™ ืžื•ืจื™ื ืžื”ืฉื•ืจื” ื”ืจืืฉื•ื ื” ืžืจื—ื‘ื™ ื”ืขื•ืœื. ืœื—ืฅ ืคืขืžื™ื™ื ืขืœ ื”ื›ืชื•ื‘ื™ื•ืช ื‘ืื ื’ืœื™ืช ื”ืžื•ืฆื’ื•ืช ื‘ื›ืœ ื“ืฃ ื•ื™ื“ืื• ื›ื“ื™ ืœื”ืคืขื™ืœ ืืช ื”ืกืจื˜ื•ืŸ ืžืฉื. ื”ื›ืชื•ื‘ื™ื•ืช ื’ื•ืœืœื•ืช ื‘ืกื ื›ืจื•ืŸ ืขื ื”ืคืขืœืช ื”ื•ื•ื™ื“ืื•. ืื ื™ืฉ ืœืš ื”ืขืจื•ืช ืื• ื‘ืงืฉื•ืช, ืื ื ืฆื•ืจ ืื™ืชื ื• ืงืฉืจ ื‘ืืžืฆืขื•ืช ื˜ื•ืคืก ื™ืฆื™ืจืช ืงืฉืจ ื–ื”.

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