Clues to Help Explain the Frequency of Injuries The three women are all serious athletes, and they work together at a small

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问题             Clues to Help Explain the Frequency of Injuries
    The three women are all serious athletes, and they work together at a small research and development firm in New Jersey.
    Frequent Injuries
    One had a single serious injury when she was a teenager doing gymnastics and skiing. One recently had a hairline crack in the tibia(胫骨), a serious-overuse injury from running. And the third has had one injury after another for the last five years. Which do you think is which:
    Jennifer Davis, 38, runs almost every day, at least 10 miles, and wears her running shoes down to a nub. She has had surgery to remove half the meniscus in her left knee after she tore it exercising, and she is missing that piece of cartilage that stabilizes the joint.
    Tara Martin, 30, is a triathlete who has competed in many triathlon sports including the Hawaii Ironman, which consists of a 2.4-mile swim, a 112-mile bike ride and a 26.2-mile run.
    Birgit Unfried, 26, has been running competitively since high school. She also uses an elliptical cross-trainer, swims and takes spinning classes at her gym. She races in 5K and 10K events, never doing the long-distance training that is needed to run a marathon.
    O. K. , it’s a trick question.
    Birgit has chronic injuries — either her knee hurts or she has excruciating shinsplints that keep her from running.
    Jen, who is my workout partner, tore her meniscus, the cartilage that helps stabilize the knee, when she was a teenager. She had surgery at 15 and has not had a serious injury since.
    And Tara, who is part of a running group that Jen and I belong to, had the hairline crack, a stress fracture, in 2006. The injury, which was devastating and which took three months to heal, occurred just when she was trying to increase her mileage for fall marathons.
    Explanation and Protection
    And that leads to some of the most difficult problems in exercise science: Why do some people become injured even though, like Birgit, they try to do everything right while others, like Jen, who flout (蔑视) every rule, avoid injury? And how can the injury-prone protect themselves?
    Exercise scientists say they have a few answers that can help with some common injuries. But all too often injuries remain a mystery and people may have to figure out how much exercise is too much for themselves and what sort of routines tend to produce injuries.
    "We don’t have enough definitive evidence to say, ’This causes an injury and even if you don’t have an injury you should change it,’" said Stephen Messier, who directs the biomechanics lab at Wake Forest University. Much of the work focuses on running injuries. But the same principles apply to swimming, tennis, bicycling or basketball.
    "I think that there is a general quality of heartiness’, or robustness,’ that may influence who gets hurt and who doesn’t," said Carl Foster, director of the human performance laboratory at the University of Wisconsin, La Crosse. "I’ve never seen any systematically collected data, and I’m not even sure what one would measure, but anyone who has worked with athletes for any time at all has seen that there are just some people who are fragile and some who aren’t."
    Sometimes injuries have a simple fix — like making sure your bicycle fits properly or improving your swimming stroke. More often, they do not. And people tend to get the same injury repeatedly.
    "My guess is that it is probably your weak link, perhaps due to your structural malalignment," said Irene Davis, the research director at the Drayer Physical Therapy Institute at the University of Delaware. "You probably have an innate predisposition for that injury."
    For example, people differ in the way their tissues, bones and ligaments respond to increased training, said Dr. Gordon Matheson, an exercise physiologist and orthopedic surgeon at Stanford University and a past editor of the journal Physician & Sportsmedicine.
    "You might increase your running 10 percent a week but I might be only be able to handle 8 percent a week," Dr. Matheson said.
    Then there is muscle strength and endurance, which also can vary from person to person. If your muscles tire, more stress is placed on bones and tendons, which can lead to injury.
    And there is the alignment of your skeleton. You might be fine running 30 miles a week, but increasing that to 40 miles means the likelihood of an injury also goes up.
    In addition, Dr. Matheson said, some people "can handle distance but not pace." He explained; "It’s a big jump from a 9-minute mile to an 8-minute mile, and shock absorption can decrease substantially making that move. "
    But Dr. Davis’ recent research has identified a few biomechanical features of people who tend to get two common injuries - runner’s knee and stress fractures of the tibia — and showed that it’s possible to change peoples’ biomechanics. The investigators, though, have not yet confirmed those findings with rigorous studies.
    Dr. Davis said that runners whose knees hurt tended to drop their hip with each step while, at the same time, their knees cave inward by an excessive amount. Using a computer monitor and cameras, she showed runners where their hips and knees were when they were running on a treadmill and where they should be. They learned to change their alignment and, according to Dr. Davis, they said their knee pain decreased.
    Stress fractures of the tibia may have a very different cause, Dr. Davis said. Those who get it often have a characteristic gait, she said. The runners tend to strike the ground hard with their heel.
    Dr. Davis’s solution is to train runners by having them run on treadmills that can measure the force of each step. The runners can see how hard their feet hit the treadmill.
    That still leaves a lot of injuries that are largely unexplained. And that means that for some people, injuries may just be a fact of life.
    You Can Still Have Fun
    Jen seems to get by unscathed. She ran the Baltimore marathon on Oct. 11, will run the New York City Marathon on Nov. 2, and will compete in a 50-mile race in Maryland a few weeks later. Tara also ran in the Baltimore marathon, three weeks after competing in a triathlon in Maryland, and is training for a marathon in Harrisburg, Pa., on Nov. 9. And Birgit is still in spinning classes and on the elliptical cross-trainer, hoping to run soon.
    But that does not mean she can’t have fun. Just ask Dr. Alan Garber, a professor of medicine at Stanford who has a daunting injury history and has learned to cope.
    It began in the late 1970s when he was preparing for a marathon and got a stress fracture of his tibia. He sought help, changed his shoes, and thought he had solved his problem. Then, a few years ago, he started running the Silicon Valley Marathon but had to stop because he was in such pain. "I could barely walk," Dr. Garber said.
    This time he had a severe stress fracture near where his calf muscles attach to his tibia. It was so bad that Stanford now uses his X-rays as a teaching tool. "It’s the worst stress fracture they have ever seen," Dr. Garber said. He spent eight weeks on crutches before beginning his path back to running.
    Last year, he fell while running down a steep hill, twisting his ankle so badly that he tore his ligaments. Another long recuperation followed. Now he’s hurt his hip from vigorous workouts on a rowing machine.
    But Dr. Garber learned to cope. "I go into recovery mode," Dr. Garber said. At each stage of his recovery, he seizes upon the things he can do.
    When he had the severe stress fracture, he could not kick when he tried to swim. So he swam with a pull buoy. The day he was finally able to kick was fabulous. He graduated to pool running, jumping into the deep end of a pool and moving his legs and arms as though he were running. He loved it. He could use an elliptical cross-trainer when he got a little better. Sheer joy.
    Ordinarily, swimming or pool running or an elliptical cross-trainer would seem like a bore to Dr. Garber. But he finds himself looking forward to those workouts. And, he said, he tells himself: "I’ve recovered before. I just have to switch to exercises that I can still do."
Stephen Messier claims that they have definite evidence to say what causes an injury.

选项 A、YES
B、NO
C、NOT GIVEN

答案B

解析 原文引用这位专家的话说,并没有确切的证据证明是什么因素会导致受伤。可见题干与文中信息相抵触,因此选择N。
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