阅读理解
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 Olympics
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 professor 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 burn about 800 calories(卡路里) per hour, which is approximately twice as many as they would burn
walking, although fewer than running, 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
uncommon among race walkers. But the sport's strange form does place
considerable stress on the ankles and hips, so people with a history of such
injuries might want to be cautious in adopting the sport. In fact, anyone
wishing to try race walking should probably first consult a coach or
experienced racer to learn proper technique, she says. It takes some practice.
