People take part in a "Bubble Run" in a park in Hohhot, capital of north China's Inner Mongolia Autonomous Region, May 30, 2015. A "Bubble Run" was held here on Saturday, in which about 2,000 young people ran on a 3-kilometer raceway covered by bubble to publicize the health and happiness concepts of sport. (Xinhua/Ding Genhou)

People take part in a"Bubble Run" in a park in Hohhot, capital of north China's Inner Mongolia Autonomous Region, May 30, 2015. A "Bubble Run" was held here on Saturday, in which about 2,000 young people ran on a 3-kilometer raceway covered by bubble to publicize the health and happiness concepts of sport. (Xinhua/Ding Genhou)

Children have fun in a "Bubble Run" in a park in Hohhot, capital of north China's Inner Mongolia Autonomous Region, May 30, 2015. A "Bubble Run" was heldhere on Saturday, in which about 2,000 young people ran on a 3-kilometer raceway covered by bubble to publicize the health and happiness concepts of sport. (Xinhua/Ding Genhou)