The inflection point is not directly related to roller skaters, but belongs to different fields and concepts. Inflexion is a mathematical term, which is usually used to describe the turning point on the function image, that is, the point where the function value changes from rising to falling or from falling to rising. In economics, inflection point is also used to describe the turning point of economic trend.
Roller skaters are people who perform roller skating. Roller skating is a kind of movement that uses rollers to slide on the ground, including speed roller skating, freestyle roller skating and other different types.