(课时作业)必修第二册 Unit 3 On the move-2023版新高考英语【红对勾】大一轮复习讲与练全新方案(外研版)

必修第二册　　　　　　　 On the move 答案 P578 (2022·陕西省洛南中学高三模拟) Race walking shares many fitness benefits with running, research shows, while most likely contributing to fewer injuries. It does, however, have its own problem. Race walkers are conditioned athletes. The longest track and field event at the Summer Olym- pics is the 50-kilometer race walk which is about five miles longer than the marathon. But the sport􀆳s rules require that a race walker􀆳s knees stay straight through most of the leg swing and one foot remain in contact ( 接 触 ) with the ground at all times. It􀆳s this strange form that makes race walking such an attractive activity, however, says Jaclyn Norberg, an assistant pro- fessor of exercise science at Salem State Universi- ty in Salem, Mass. Like running, race walking is physically de- manding, she says. According to most calcula- tions, race walkers moving at a pace of six miles per hour would burn about 800 calories per hour, which is approximately twice as many as they would burn walking, although fewer than run- ning, which would probably burn about 1,000 or more calories per hour. However, race walking does not pound the body as much as running does, Dr Norberg says. According to her research, runners hit the ground with as much as four times their body weight per step, while race walkers, who do not leave the ground, create only about 1. 4 times their body weight with each step. As a result, she says, some of the injuries associated with running, such as runner􀆳s knee, are unco