Here kinetics is taken to include two connected notions: kinetics as addressed in physics and linked rigid-body kinetics. The first version means the study of the determinants of motion, while the second refers to the movement of interconnected bodies under the action of external forces. Transferred to the human body, the latter treats ‘bodies’ as ‘segments’ or a system of rigid bodies. For analytical purposes, the human body can be modeled as consisting of a number of such segments, in fact up to 14 to 15 depending on the model used. Given, however, that body segments are interlinked at the joints and thus interact with each other, making the analysis of biological movements much more complicated than one just based on rigid-body kinetics. Over time the term ‘kinetics’ treated in this way has given way to ‘dynamics’ in both physics and biomechanics. The (classical) dynamics of a rigid-body system are captured by its equations of motion derived, for example, from Newton’s second law of motion. In turn, this law has to broaden to include the system of forces and torques that act on a the motion of a biological system.
See Biomechanics, Dynamics, Force, Kinematics, Movement (or motor) coordination, Newtonian (or classical) mechanics, Newton’s law of motion, Torque