Mouth guards and related systems and methods for determining linear and angular accelerations of the head of a subject. A plurality of accelerometers are operatively associated with the mouth guard and spaced from one another about the mouth guard. The accelerometers produce outputs indicative of the linear and angular acceleration of the mouth guard. Optionally, the mouth guard can be used in conjunction with a helmet that is provided with a plurality of accelerometers spaced about the helmet. In use, the outputs of the accelerometers of the helmet can be correlated to the outputs of the accelerometers of the mouth guard.
