The fitness movement that began in the late 1960s and early 1970s centered around aerobic exercise. Millions of individuals became (1) in a variety of aerobic activities, and (2) thousands of health spas (3) around the country to capitalize on this (4) interest in fitness, particularly aerobic dancing for females.A、number of fitness spas existed (5) to this aerobic fitness movement, even a national chain with spas in most major cities. However, their (6) was not on aerobics, (7) on weight-training programs designed to develop muscular mass, (8) , and endurance in their primarily male (9) . These fitness spas did not seem to benefit (10) from the aerobic fitness movement to better health, since medical opinion suggested that weight-training programs (11) few, if (12) , health benefits. In recent years, however, weight training has again become increasingly (13) for males and for females. Many (14) programs focus not only on developing muscular strength and endurance but on aerobic fitness as well. (15) , most physical-fitness tests have usually included measures of muscular strength and endurance, not for health-related reasons, but primarily (16) such fitness components have been related to (17) in athletics. (18) , in recent years, evidence has shown that training programs designed primarily to improve muscular strength and endurance might also offer some health (19) as well. TheAmericanCollege of Sports Medicine now (20) that weight training be part of a total fitness program for healthyAmericans.