A system and method using a single 3D motion sensing Microsoft Kinect for Windows augmented with computer vision algorithms for detecting, recognizing and tracking the movement of different joints of the body of a subject and deducing kinetic and kinematic data from those movements. The method requires only a single motion sensing device and is non-invasive as the subject does not need to wear any external devices on the body. The proposed method incorporates Second Life serious game environment where the patient, the therapist and other members of the community of interest can log-in any time and see all the subject's movements performed by an avatar in Second Life, thereby making the invention particularly useful for disabled hemiplegic children.