科学研究证明，使用兴奋剂会对人的身心健康产生许多直接的危害，使用不同种类和不同剂量的禁用药物，对人体的损害程度也不相同。还有一点也是对运动员不公平，所以目前兴奋剂是严于使用的。
From federal investigations into Major League Baseball(美国职业棒球大联盟) to allegations of substance abuse in track and field, performance enhancing drugs(兴奋剂) have been in the news a lot. The most well-known performance enhancers are steroids(类固醇), drugs that can make athletes bigger and stronger. But they can also cause serious medical problems.
So how do steroids work, and what makes them so dangerous?
First, it’s important to understand that the body naturally produces steroids. For men, the best known is testosterone(睾丸激素). Testosterone is an anabolic steroid(合成代谢类固醇), meaning that it encourages new muscle growth. So the more testosterone you have in you, the greater potential you have to be bigger and stronger. It makes sense, then, that artificial anabolic steroids mimic testosterone produced in the body.
Here’s how they work. Anabolic steroids attach to cells and encourage them to produce more protein, which muscles need to grow and become stronger. So steroids basically (1)speed up and enhance the process of muscle growth that you can accomplish by lifting weights and other kinds of exercise. A weightlifter on steroids will develop larger muscles and do so faster than a “clean” weightlifter.
Millions of people take performance enhancing drugs such as caffeine and vitamins every day. But unlike these drugs, steroids can cause serious, long lasting problems. For example, steroid use puts extra pressure on the liver to cleanse the bloodstream of the many toxins in steroids.
Prolonged steroid use can result in liver damage. They also affect brain chemistry(脑化学), and can cause depression and severe mood swings known as ‘roid rage(类固醇癫狂)’. There’s certainly nothing wrong with building your body, but using steroids to do so will ultimately (2)break you down.Toefl
译文：
兴奋剂，让人沉浮
从对美国职业棒球大联盟药物滥用指控的联邦调查来看，服用兴奋剂已经成为一个热门话题。其中最著名的兴奋剂是类固醇，它可以让运动员更大更强。但是它们也会导致严重的医学问题。
那么类固醇是怎样发挥作用的呢?是什么使它们如此危险?
首先，知道身体能够自然产生类固醇是很重要的。对于男性来说，最广为大家所知的就是睾丸激素。睾丸激素是一种合成代谢类固醇，它能够促进新的肌肉的生长。因此如果你的睾丸激素越多，你的潜力就越大越强。这样一来，人造合成类固醇模仿人体内分泌的睾丸激素应运而生了。
它们是这样工作的。合成类固醇依附于细胞上，促使它们产生更多肌肉生长和壮大所需要的蛋白质。因此类固醇主要是加快和加强肌肉生长，而这样的效果你可以通过举重和其它的运动练习达到。一个服用类固醇举重运动员的肌肉会比一个“干净”的运动员生长得更大更快。
成千上万的人们每天都在服用咖啡因，维他命之类的兴奋剂。但是与其它药物不同的是类固醇会导致严重，持久的问题。例如，使用胆固醇会对肝脏净化血液带来压力，因为胆固醇里有很多毒素。
长期使用类固醇可导致肝损害。它们同样会影响脑化学，并会导致抑郁症和被称为“类固醇癫狂”的严重情绪波动。强身健体当然没有错误，但是如果你使用类固醇来完成，那么最终你会垮掉。