Passage 2

Jogging has become the most popular individual sport in USA. It has become commonplace to see people of all ages running along city streets, in parks and along special jogger’s trails that have been built in some cities. Many theories, even some mystical ones, have been advanced to explain the popularity of jogging. The plain truth is that jogging is a cheap, quick, and efficient way to maintain physical fitness.

The most useful sort of exercise is exercise that develops the heart, lungs, and circulatory systems. If these systems are fit, the body is ready for almost any sport and for almost any sudden demand made by work or emergencies. One can train more specifically as by developing strength for weight lifting or the ability to run straight ahead for short distances with great power as in football, but running trains your heart and lungs to deliver oxygen more efficiently to all parts of your body. It is worth noting that this sort of exercise is the only kind that can reduce heart disease, the number one cause of death in USA. Only one sort of equipment is needed—a good pair of shoes. Physicians advise beginning joggers not to try to run in tennis or gym shoes. Many design advances have been made in only the last several years that make an excellent running shoe essential if a runner wishes to develop as quickly as possible, with as little chance of injury as possible. A good running shoe will have a soft pad forabsorbingshock, as well as a slightly built-up heel and a full heel cup that will give the knee and ankle more stability. A wise investment in good shoes will prevent blisters and foot, ankle, and knee injuries and will enable the wearer to run on paved or soft surface.

No other special equipment is needed, you can jog in any clothing you desire, even your street clothes. Many joggers wear expensive, warm-up suits, but just as many wear a simple gym shorts and a T-shirt. In fact, many people just jog in last year’s clothes. In cold weather, several layers of clothing are better than one heavy sweater or coat. If joggers are wearing several layers of clothing, they can add or subtract layers as conditions change. It takes surprisingly little time to develop the ability to run. The American Jogging Association has a twelve-week program designed to move from a fifteen-minute walk to a thirty-minute run. A measure of common sense, a physical examination and planned schedule are all it takes.

 The main purpose of this passage is to ______ .