雅思话题准备之锻炼的前世今生

雅思考试主要是通过对考生听、说、读、写四个方面英语能力的考核，综合测评考生的英语沟通运用能力，实现“沟通为本”的考试理念。对于雅思考生来说，也有很多考试难点和政策盲区需要帮助解答。今天雅思无忧网小编准备了雅思话题准备之锻炼的前世今生，希望通过文章来解决雅思考生这方面的疑难问题，敬请关注。

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exercise

Introduction
the training of the body to improve its function and enhance its fitness.

The terms exercise and physical activity are often used interchangeably, but this article will distinguish between them. Physical activity is an inclusive term that refers to any expenditure of energy brought about by bodily movement via the skeletal muscles; as such, it includes the complete spectrum of activity from very low resting levels to maximal exertion. Exercise is a component of physical activity. The distinguishing characteristic of exercise is that it is a structured activity specifically planned to develop and maintain physical fitness. Physical conditioning refers to the development of physical fitness through the adaptation of the body and its various systems to an exercise program.

 

A historical view of exercise
Prehistoric period
Hominids—human beings and their immediate ancestors—have existed on Earth for at least 2,000,000 years. For more than 99 percent of that time, hominids lived a nomadic existence and survived by hunting and gathering food. It is obvious that this way of life was enormously different from the way people live today in developed countries. Thus, evolutionary history has prepared humankind for one kind of life, but modern people lead another. This fact has profound implications for patterns of disease and for the association between living habits and health. Observation of the few remaining nomadic groups in the world indicates that they are relatively free of chronic diseases and that, in comparison to the populations in developed countries, they are leaner, have a higher level of physical fitness, eat a very different diet, and have different physical activity patterns. Data from the distant past are not available, but it is reasonable to speculate that early humans had considerably higher caloric expenditures per unit of body weight than do modern individuals.

 

Agricultural period
As civilization developed, nomadic hunting and gathering societies gave way to agricultural ones in which people grew their own food and domesticated animals. This development occurred relatively recently, approximately 10,000 years ago. Although many aspects of life changed during the agricultural period, it is likely that energy demands remained high, with much of the work still done by human power. Even in cities—which had evolved by about midway through the agricultural period—individuals expended more calories than do most people today.

 

Industrial period
The industrial period began during the mid-18th century, with the development of an efficient steam engine, and lasted to the end of World War II (1945). This relatively brief time span was characterized by a major shift in population from farms to cities, with attendant changes in many areas of life-style. Even though the internal-combustion engine and electrical power were increasingly used to perform work, the great majority of individuals in industrialized societies still faced significant energy demands. In the cities relatively more individuals walked to work, climbed stairs, and had more physically demanding jobs than do most people today.

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