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
2023-09-16
30
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 he 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/3019689.html
相关试题推荐
[originaltext]W:SweetHomeFurniture,canIhelpyou?M:Yes,[8]I’dliketob
[originaltext]W:SweetHomeFurniture,canIhelpyou?M:Yes,[8]I’dliketob
[originaltext]W:WhenareyouleavingforCambridge,Dr.Berle?M:OnWednesda
[originaltext]W:WhenareyouleavingforCambridge,Dr.Berle?M:OnWednesda
Atwhattimeofdaydidthefirestart?Intheearly______.[br][originaltext]
Atwhattimeofdaydidthefirestart?Intheearly______.[originaltext]No
[originaltext]W:Hello,AirChinaWhatcanIdoforyou,Sir?M:CanIbookat
[originaltext]W:Hello,AirChinaWhatcanIdoforyou,Sir?M:CanIbookat
[originaltext]W:Hi,Jack.Howwasyourweekend?M:Fine,[6]Iwentbacktomy
[originaltext]W:Hi,Jack.Howwasyourweekend?M:Fine,[6]Iwentbacktomy
随机试题
HewasoutwhenIcalled,butthesecretarykindlyoffered______amessageforme
[originaltext]Manyforeignstudentsareattractednotonlytotheacademic
Worriedaboutprescriptiondrugs?Howtoweighyourrisk?When
公司决定邀请部分专家学者开会,商定对策。这类会议属于()。A.听证性会议 B
患儿,男,4岁。右腰部间断胀痛6个月。无血尿、尿频、尿急和尿痛,无排尿困难。查体
下列关于违约概率(PD)的说法,正确的是()。A.某一债项违约导致的损失金额
木类中药的药用部位是A.草本植物茎形成层以外各部分B.草本植物茎形成层以内各部分
经过较长时期的稳定发展以后,社会上又会有新的技术和新的行业出现,消费者偏好逐渐转
根据使用目的的不同,控制图可分为()。 A.分析用控制图B.正态分布控制图
根据《水利工程建设项目管理规定》(水建[1995]128号),水利工程建设项目按
最新回复
(
0
)