The fitness movement that began in the late 1960s and early 1970s centered around aerobic exercise (有氧操). Millions of individuals became engaged in a variety of aerobic activities, and literally thousands of health spas developed around the country to capitalize (获利) on this emerging interest in fitness, particularly aerobic dancing for females. A number of fitness spas existed prior to this aerobic fitness movement, even a national chain with spas in most major cities. However, their focus was not on aerobics, but rather on weight-training programs designed to develop muscular mass, strength, and endurance in their primarily male enthusiasts. These fitness spas did not seem to benefit financially form the aerobic fitness movement to better health, since medical opinion suggested that weight-training programs offered few, if any, health benefits. In recent years, however, weight training has again become increasingly popular for males and for females. Many current programs focus not only on developing muscula