Walking-like swimming，bicycling and running--is an aerobic exercise，(31)___builds the capacity for energy output and physical endurance by increasing the supply of oxygen to skin and muscles.Such exercises may be a primary factor in the(32) ___0f heart and circulatory disease.
As probably the least strenuous，safest aerobic activity，walking is the(33) ___acceptable exercise for the largest number of people.Walking(34) ___comfortable speed improves the efficiency of the cardio respiratory system(35) ___stimulating the lungs and heart，but at a more gradual rate(36) ___most other forms of exercise.
In one test，a group of men 40 t0 57 years of age，(37) ___at a fast pace for 40 minutes four days a week，showed improvement(38) ___to men the same age on a 30 minute，three—day—a—week jogging program in the same period.Their resting heart rate and body fat decreased(39) ___.These changes suggest(40) ___of the important-even vital--benefits walking can(41) ___about.
Walking(42) ___burns calories.It takes 3，500 calories to gain or(43) ___0ne pound.Since a one.hour walk at a moderate pace will(44) ___up 300 t0 360 calories.By walking one hour every other day，you Can burn up a pound—and—a—half monthly，or l8 pounds(45) ___-providing there is no change in your in-take of food.To(46).___weight faster，walk an n hour every day and bum up 3 pounds a month，or 36 pounds a year.
(47) ___your age，right now is the time to give your physical well-being as much thought as you(48) ___to pensions or insurance.Walking is a vital defense(49) ___the ravages of degenerative diseases and aging.It is nature’s (50) ___of giving you a tuneup.
参考译文：
行走就像游泳、骑自行车和跑步一样，是一种有氧运动，可以通过给皮肤和肌肉增加供氧而塑造更大的肺活量和耐力。这样的运动可能是防止心脏和血液循环疾病的一个主要因素。
作为可能是最不费力气、最安全的有氧运动，绝大多数人认为行走可以接受。以舒适的速度行走可以通过激活肺部和心脏增强心肺系统的效率，但比起大多数其他的锻炼形式，行走的速度更为舒缓。
在一项测试中，一组40到57岁的男子每周4天快速行走40分钟，与同样年龄每周同期进行3次30分钟慢跑的男子收到了同样的改善效果。他们的正常心率和身体脂肪明显降低。这些变化表明行走可以带来重要的，甚至是关键的益处。
行走也可以燃烧热量。获得或失去一磅重量需要消耗3 500卡热量。因为以中等速度走一小时的路程将会消耗300到360卡的热量。每隔一天行走一小时，则每月可以减去一磅半的脂肪，或者说一年可以减去18 磅脂肪，只要您每日摄入的食物量不变。为了更快减去体重，每天行走一小时，那么每月就可以减去3磅脂肪，一年就是36磅。
不管您的年龄有多大，现在都应该花同样时间考虑身体和养老金或保险。行走是一种关键的抵御疾病和抗衰老的方法。它是自然界给您的一种调整的方式。
