You finish a workout and feel great. Then you get up the next morning and your exercised m

You finish a workout and feel great. Then you get up the next morning and your exercised muscles feel sore. You find it hard to lift your arms and brush your teeth, or bend down to pick up a book. What has happened?
Scientists call this soreness 24 to 48 hours after your exercise “delayed onset (延迟发作) of muscle soreness”, or DOMS. It is caused by microscopic damage to muscle fibers, which releases chemicals. The chemicals irritate (刺激) nerve fibers and cause pain.
Muscle soreness is a good sign. It means that you have challenged your muscles and are getting stronger. Everyone experiences it, even the best athletes. But it can be avoided by using the right exercise methods. Here are some tips:
* Warm up before you work out. This is helpful to avoid muscle soreness, but more importantly to avoid injury. It starts circulation to the muscles and warms the muscles and tendons, getting them ready for exercise.
* Stretch after your workout. After exercising, make sure you stretch your muscles for 15 to 20 seconds before they cool down. They will be warm and elastic (弹性的) so they will stretch well.
* Don’t do too much too soon. Whether it’s jogging, running, whatever workout routine you are starting, just do half of the exercise volume the first week to introduce your muscles to the exercises.
If you are already feeling muscles soreness, here are some ways to help relieve it.
* Get a massage (按摩). Lightly massage the sore muscle and gradually increase the depth of the massage. It might be painful in the beginning but it will gradually ease the muscle soreness.
* Take a hot bath. Nothing beats a long soak in a hot bath for muscle soreness. The heat will increase circulation and provide a soothing (舒缓) effect.
* Flush your muscles. Run hot (as hot as you can bear) water over the sore muscles for two minutes and then immediately switch to cold water for 30 seconds. Repeat this process five times. This has the effect of opening and closing your blood vessels (血管). It will flush the acid (酸物质) from them and ease the soreness.
* Exercise gently. Go for a slow walk and breathe deeply. This helps reduce muscle soreness by increasing blood flow to the sore muscles.
72. What is the purpose of this article?
A. To tell readers to exercise more for fitness.
B. To warn readers of the side effects of exercise.
C. To give readers advice on how to avoid and relieve muscle soreness.
D. To introduce good forms of exercise.
73. The article suggests that before exercise we should     .
A. stretch our muscles                   B. have a massage
C. have a hot shower                   D. warm up our muscles
74. From this article we can conclude that muscle soreness is caused by     .
A. damaged muscle fibers               B. damaged nerve fibers
C. a bad circulation to the muscles        D. exercise injuries
75. Judging from the article, which of the following statements is TRUE?
A. Only beginners get muscle soreness.
B. Muscle soreness means you have physical problems and should stop exercising.
C. Muscle soreness is a good sign because it means that the muscles are getting stronger.
D. Muscle soreness can be relieved by increasing the amount of exercise.B