The greatest benefit of regular exercise program is an improvement in overall fitness. Appropriate exercise improves muscular strength and endurance， body composition， flexibility①and cardiorespiratory endurance②.The level of maximal oxygen intake or cardiorespiratory endurance is not by itself great importance to most individuals. What is important is that one’s sustained energy-spending ability is directly related to maximal levels of performance. For example， consider the simple task of walking at a rate of three-mile per hour. This task involves an energy expenditure of approximately three times the rest hgmetabolic rate. For such individuals a three-mile hour walk requires half of their maximal capacity. A middle-aged person who exercises regularly will have a maximal aerobic③ power 10 to 12 times resting， so the same walk will represent only 25 to 30 percent of maximal capacity.
A person’s maximal cardiorespiratory endurance④determines how active a life-style can be sustained. Individuals who attempt to lead more active lives than their fitness level will support become chronically fatigued⑤.
Exercise habits are strongly related to body weight. In virtually all studies of large populations， the more active individuals weigh less. Weight-loss programs than incorporate exercise as well as diet are more successful than those that rely on⑥ diet⑦ alone.
① flexibilityn. 柔韧性
② cardiorespiratory endurance心肺耐受力
③ aerobicadj. 有氧的，耗氧的
④ maximal cardiorespiratory endurance最大心肺耐受力
⑤ fatiguevi. 疲乏，衰弱 n. 疲劳，劳累
⑥ rely on依靠
⑦ dietvi. 进规定的饮食；忌食；节食 n. 饮食，食物
定期锻炼计划
定期锻炼计划的最大益处是能全面增强身体素质。适当的锻炼能提高肌肉的力量和持久性，改善人的身体结构和柔韧性，增加心肺的耐受力。氧气的最大吸入量和心肺耐受力本身对大数人来说并不十分重要，重要的是人体稳定的能量消耗能力与这些性能的最高水平有直接关系。以每小时三英里的慢速行走这个简单的任务为例。这项行为需要消耗的能量大约是安静状态下生理代谢的3倍，对这些参加运动的人而言，每小时三英里的行走需消耗他们最大体力的一半。一个定期锻炼的中年人能达到的最高耗氧量是安静状态下的10到20倍，所以相同的行走只需他最大耐受力的25％—30％。
一个人的最大心肺耐受力决定了他能采取多种活跃的方式来生活。如果尝试一种超过自己承受能力的更大活动量的生活，这些人会长期感觉疲乏。
锻炼习惯与体重密切相关。事实上对大量人群的所有研究都表明，越爱动的人体重越轻。锻炼和节食相结合的减肥计划比光依靠节食的计划要有效得多。
