高架桥是城市的交通大动脉。高架桥下留出的一片片空地，有的被建成停车场或库房，有的则被绿化起来，吸引了不少人前去锻炼身体。不过，高架桥下的空地虽然是一个便于人们活动的空间，但却实在不是一个合适的锻炼地点，因为在此健身会对人体健康造成负面影响。众所周知，机动 Viaduct is the city’s traffic arteries. The viaduct set aside a piece of open space, and some have been built into the parking lot or warehouse, while others are green up, attracting a lot of people went to exercise. However, although the open space under the viaduct is a space for people’s activities, it is not a proper place to exercise because exercise can have a negative impact on human health. As we all know, maneuvering