In this chapter, first we outline the advantage of new technologies based on body-fixed sensors and particularly the possibility to perform field measurement, out of a laboratory and during the actual condition of the subject. The relevance of intelligent computing and its potential to enhance those features hidden in biomechanical signals are reviewed. An emphasis is made to show the results produced by these sensors when used alone and new possibilities offered when the information from different type of body fixed sensors are fused. In the second part, the relevance of body fixed sensors in medicine is presented by providing many clinical applications in orthopedics, Parkinson disease, physiology, pain management, and aging. Finally the chapter ends by emphasizing the potential of synergies between body fixed movement monitoring and other areas such as information technology which lead to the development of wearable body movement monitoring.