Acceleration sensors are being considered in several studies for integration in wearable sensor systems that are conceived for a wide range of applications. An interesting application of accelerometry concerns the determination of the inclination of different body parts with respect to the vertical. There is wide consensus that the technology of microelectromechanical systems accelerometers and the continuing progress in information and communication technologies will combine to produce innovative practices of healthcare management. Accelerometers are capable of measuring the intensity and frequency of human motion. Rehabilitation, sleep disorders, and attention and personality disorders, notably in children, can also be investigated through accelerometry-based physical activity monitors. A. Barnett and E. Cerin use a commercial device for physical activity assessment, namely the Massachusetts Institute of Technology/CSA Actigraph. Human activity can be recognized through ultrasonic or electromagnetic localization systems or optoelectronic marker-based or markerless motion analysis. Gait analysis plays a fundamental role for functional assessment of physical daily activities.