Wang Yibo wipes the sweat off his face in Xi'an. He has made running his second career.[Photo/CFP]

"I worked as Wen's private fitness coach, and I designed the running especially according to his physical and psychological characteristics, to adjust the breathing, frequency and time he needed to run to get fit," Wang said.

Liu Qiangdong, chief lawyer of Xi'an Dongsen Law Firm, said accompanied running could not be defined as a business because the two parties do not sign a contract. "The two parties should fully discuss their expectations and understand each other before they provide or make use of such a service, in order to avoid risks and disputes," the lawyer said.

Du Pengcheng, professor with Xi'an Institute of Physical Education, said that from the perspective of sports medicine, night running is healthy. "Once you have the proper intensity of exercise, the slight fatigue caused by night running will make you sleep better," Du said.