It's this strange form that makes race walking such an attractive activity, however, says Jaclyn Norberg, an assistant professor of exercise science at Salem State University in Salem, Mass.

You’d be stuck contemplating the mass of idling cars, a mental exercise that is much less pleasant than dreaming about a beach and much less useful than mulling what to do once you get off the road.

The researchers say that an environment based on mass transit influences health, because rail users are get exercise walking to and from stops.