20、 Obama
中級 42359 分類 收藏
開始影片後，點擊或框選字幕可以立即查詢單字
字庫載入中…
回報字幕錯誤
Muscles.
We have over 600 of them.
They make up between 1/3 and 1/2 of our body weight,
and along with connective tissue,
they bind us together, hold us up, and help us move.
And whether or not body building is your hobby,
muscles need your constant attention
because the way you treat them on a daily basis determines whether they will wither or grow.
Say you're standing in front of a door, ready to pull it open.
Your brain and muscles are perfectly poised to help you achieve this goal.
First, your brain sends a signal to motor neurons inside your arm.
When they receive this message, they fire,
causing muscles to contract and relax,
which pull on the bones in your arm and generate the needed movement.
The bigger the challenge becomes, the bigger the brain's signal grows,
and the more motor units it rallies to help you achieve your task.
But what if the door is made of solid iron?
At this point, your arm muscles alone won't be able to generate enough tension to pull it open,
so your brain appeals to other muscles for help.
You plant your feet, tighten your belly, and tense your back,
generating enough force to yank it open.
Your nervous system has just leveraged the resources you already have, other muscles, to meet the demand.
While all this is happening,
your muscle fibers undergo another kind of cellular change.
As you expose them to stress, they experience microscopic damage, which, in this context, is a good thing.
In response, the injured cells release inflammatory molecules called cytokines
that activate the immune system to repair the injury.
This is when the muscle-building magic happens.
The greater the damage to the muscle tissue,
the more your body will need to repair itself.
The resulting cycle of damage and repair
eventually makes muscles bigger and stronger
as they adapt to progressively greater demands.
Since our bodies have already adapted to most everyday activities,
those generally don't produce enough stress to stimulate new muscle growth.
So, to build new muscle, a process called hypertrophy,
our cells need to be exposed to higher workloads than they are used to.
In fact, if you don't continuously expose your muscles to some resistance,
they will shrink,
a process known as muscular atrophy.
In contrast, exposing the muscle to a high-degree of tension,
especially while the muscle is lengthening,
also called an eccentric contraction,
generates effective conditions for new growth.
However, muscles rely on more than just activity to grow.
Without proper nutrition, hormones, and rest,
your body would never be able to repair damaged muscle fibers.
Protein in our diet preserves muscle mass
by providing the building blocks for new tissue in the form of amino acids.
Adequate protein intake, along with naturally occurring hormones,
like insulin-like growth factor and testosterone,
help shift the body into a state where tissue is repaired and grown.
This vital repair process mainly occurs when we're resting,
especially at night while sleeping.
Gender and age affect this repair mechanism,
which is why young men with more testosterone
have a leg up in the muscle building game.
Genetic factors also play a role in one's ability to grow muscle.
Some people have more robust immune reactions to muscle damage,
and are better able to repair and replace damaged muscle fibers,
increasing their muscle-building potential.
The body responds to the demands you place on it.
If you tear your muscles up, eat right, rest and repeat,
you'll create the conditions to make your muscles as big and strong as possible.
It is with muscles as it is with life:
Meaningful growth requires challenge and stress.
提示：點選文章或是影片下面的字幕單字，可以直接快速翻譯喔！

載入中…

載入中…

中級

【TED-Ed】想要有肌肉嗎? 那就快來看看肌肉是怎麼形成的吧! (What makes muscles grow? - Jeffrey Siegel)

42359 分類 收藏
SylviaQQ 發佈於 2016 年 2 月 26 日    Clément 翻譯    Kristi Yang 審核

影片學習單字重點

loading
看更多推薦影片

影片討論

載入中…

  1. 1. 單字查詢

    在字幕上選取單字即可即時查詢單字喔！

  2. 2. 單句重複播放

    可重複聽取一句單句，加強聽力！

  3. 3. 使用快速鍵

    使用影片快速鍵，讓學習更有效率！

  4. 4. 關閉語言字幕

    進階版練習可關閉字幕純聽英文哦！

  5. 5. 內嵌播放器

    可以將英文字幕學習播放器內嵌到部落格等地方喔

  6. 6. 展開播放器

    可隱藏右方全文及字典欄位，觀看影片更舒適！

  1. 英文聽力測驗

    挑戰字幕英文聽力測驗！

  1. 點擊展開筆記本讓你看的更舒服

  1. UrbanDictionary 俚語字典整合查詢。一般字典查詢不到你滿意的解譯，不妨使用「俚語字典」，或許會讓你有滿意的答案喔