Abstract: Movement-based and exertion interfaces assume that their users move. Users have to perform exercises, they have to dance, they have to golf or football, or they want to train particular bodily skills. Many examples of those interfaces exist, sometimes asking for subtle interaction between user and interface and sometimes asking for "brute force" exertion interaction between user and interface. In these interfaces it is often the case that the interface mediates between players of a game. Obviously, one of the players may be a virtual human. We provide a "state of the art survey" of such interfaces and in particular look at intelligent exertion interfaces, interfaces that know about their users and even try to anticipate what their users prepare to do. That is, we embed this interface research in ambient intelligence and entertainment computing research, and the interfaces we consider are not only mediating, but they also "add" intelligence to the game. Other issues that will be discussed are "flow" and "engagement" for exertion interfaces. Intelligent exertion interfaces, being able to know and learn about their users, should also be able to provide means to keep their users engaged and in the flow of the game and entertainment experience. Unlike the situation with traditional desktop game research where we can observe lots of research activity trying to define, interpret and evaluate issues such as "flow" and "immersion," in movement-based interfaces these concepts need to be reconsidered and new ways of evaluation have to be defined.