Cientos de chinos se mueven al unísono a orillas de un río en el noreste del país, al tiempo que practican una sorprendente danza-gimnasia, muy popular entre las personas mayores.br br Participants in 'Happy Dancing' perform a series of unconventional moves, from strutting with puffed-out chests to pinwheeling their arms. br br Founder Yu Jicheng, 73, says the exercises stand out for their focus on "the shoulders and hips".