The virtues of physical fitness are shown on magazine covers, postage stamps, and television ads for everything from beauty soaps to travel books. Exercise as a part of daily life did not catch on until the late 1960s when research by military doctors began to show the health benefits of doing regular physical exercises. （Growing publicity (宣传) for races held in American cities helped fuel a strong interest in the ancient sport of running. ）
Although running has leveled off in recent years as Americans have discovered equally rewarding-and sometimes safer-forms of exercise, such as walking and swimming, running remains the most popular form of exercise.
不用全翻译，就是翻译（）中这句。前后我是给语境你参考。主要是races ，指比赛还是种族运动？fuel a strong interest 怎么理解？
