This book presents the most important aspects of analysis of dynamical processes taking place on the human body surface. It provides an overview of the major devices that act as a prevention measure to boost a person‘s motivation for physical activity. A short overview of the most popular MEMS sensors for biomedical applications is given. The development and validation of a multi-level computational model that combines mathematical models of an accelerometer and reduced human body surface tissue is presented. Subsequently, results of finite element analysis are used together with experimental data to evaluate rheological properties of not only human skin but skeletal joints as well.