Abstract
Equipment for musculoskeletal testing and rehabilitation has evolved tremendously in recent years. This article presents a brief history of this evolution followed by more detailed coverage of the current state of the art. Terminology and concepts related to muscle function, muscle loading, and motor control theory are defined. The clinical relevance and application of isokinetic equipment, in particular “active” systems, are discussed. The components of an active dynamometer are described, followed by an explanation of how it is controlled. The concluding section briefly presents trends and likely future applications of active systems and related technology.