【英语】
[大题] cRace walking shares many fitness benefits with running, research shows, while mostlikely contributing to fewer injuries. It does, however, have its own problem.Race walkers are conditioned athletes. The longest track and field event at the SummerOlympics is the 50-kilometer race walk, which is about five miles longer than the marathon.But the sport's rnules require that a race walker's knees stay straight through most of the legswing and one foot remain in contact (接触) with the ground at all times. It's this strange formthat makes race walking such an attractive activity, however, says Jaclyn Norberg, an assistantprofessor of exercise science at Salem State University in Salem, Mass.Like running, race walking is physically demanding, she says. According to most calculations,race walkers moving at a pace of six miles per hour would bum about 800 calories (卡路里)per hour, which is approximately twice as many as they would bum walking, although fewerthan running, which would probably bumn about 1,000 or more calories per hour.However, race walking does not pound the body as much as running does, Dr. Norbergsays. According to her research, runners hit the ground with as much as four times their bodyweight per step, while race walkers, who do not leave the ground, create only about 1.4 timestheir body weight with each step.As a result, she says, some of the injuries associated with nunning, such as runner's knee,are uncommon armong race walkers. But the sport's strange forn does place considerable stresson the ankles and hips, so people with a history of such injuries might want to be cautious inadopting the sport. In fact, anyone W ishing to try race walking should probably first consult acoach or experienced racer to learn proper technique, she says. It takes some practice.
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