首页
登录
职称英语
[originaltext] A world-champion body builder has no more muscles than does a
[originaltext] A world-champion body builder has no more muscles than does a
游客
2024-06-16
2
管理
问题
A world-champion body builder has no more muscles than does a 90-pound weakling. So what makes him so strong? What other qualities does be need?
Muscles are made of thousands of stringy fibers—a number that is fixed during childhood—which contract when doing work. Strength does not depend on the number of fibers but on the function of their thickness and how many of them contract simultaneously.
Exercise actually damages the muscles. During the recovery stage, the muscle fibers increase in size. Exercise also trains more muscle fibers to work at one time. If a muscle is weak or untrained, for example, only about 10 percent of its fibers will contract, whereas up to 90 percent of the fibers in a weight lifter’s bulky biceps will contract.
Aside from strength, two other ingredients go into making an athlete: fitness and endurance. Fitness is related to the condition of the heart. During exercises, there is an increase in the amount of blood returning to the heart from the muscles. A typical volume for a runner at rest is about 5 quarts a minutes, compared with 30 quarts during a vigorous trial. This greater volume means more work for the heart a muscular balloon that expands and contracts to take in blood and squeeze it out. Like any other muscle, the heart enlarges and gets stronger with routine exercise.
Endurance, or the length of time muscles can work, depends in part on how much fuel—in this case sugar—the muscles can store. A muscle that is continually exercised until it is exhausted of sugar tends to store more when it refuels at the next meal. And more sugar can translate into greater endurance the next time the muscle is put to the test.
选项
A、The Sources of strength.
B、Body building.
C、Strong heart.
D、Strength, fitness and endurance.
答案
A
解析
What does the passage mainly discuss?
转载请注明原文地址:https://tihaiku.com/zcyy/3637172.html
相关试题推荐
[originaltext]M:Howdidyoulikethefireworkslastnight?W:Ireallydidn’t
[originaltext]M:Howdidyoulikethefireworkslastnight?W:Ireallydidn’t
[originaltext]W:Theshirtsellsfor3dollarseach,butit’s5ifyoubuytwo.
[originaltext]W:Theshirtsellsfor3dollarseach,butit’s5ifyoubuytwo.
[originaltext]W:WhatcanIdoforyou?M:Yes,Iwouldlikesometicketsforn
[originaltext]W:WhatcanIdoforyou?M:Yes,Iwouldlikesometicketsforn
[originaltext]M:MayIhelpyou?W:Yes,myfriendisfinishingmiddlehighsch
[originaltext]M:MayIhelpyou?W:Yes,myfriendisfinishingmiddlehighsch
[originaltext]W:Gotobedearlyandgetsomerest,Jack.M:ButIhavetostu
[originaltext]W:Gotobedearlyandgetsomerest,Jack.M:ButIhavetostu
随机试题
InterculturalLearningManyteachersmaywonder"Wha
Thespeakermainlydiscusses______.[br][originaltext]Intheearly1800s
[audioFiles]audio_eham_j73_001(20082)[/audioFiles]A、Inthepark.B、Betweentwo
Forthispart,youareallowed30minutestowriteacompositiononthetopicFi
后备副本的主要用途是()A.数据转储 B.历史档案 C.故障恢复 D.安
A.连续且可导 B.连续且可微 C.连续不可导 D.不连续不可微
(2012年真题)根据合同法律制度的规定,下列情形中,属于不可抗力的有()
防止失控车辆越过中央分隔带或在路侧比较危险的路段冲出路基,不致发生二次事故,应设
患者知觉体验中表现为错觉的是 A.看见面前的高楼变矮了 B.将输液管看成是一
项目各参与方沟通过程的五个要素是指沟通主体、沟通客体、沟通介体以及()。A
最新回复
(
0
)