An apparatus as provided for measuring acceleration of a person's head or other object. The apparatus comprises a sensor for sensing acceleration and a controller for controlling recording of data resulting from the sensed acceleration due to an explosive force. The controller is adapted to determine whether or not to enable recording of the data based on the sensed acceleration. A data receiver is provided to receive the sensed acceleration data from the sensing means, and requires electrical power to enable data to be received thereby. The controller controls electrical power to the receiver so that if the sensed acceleration reaches or exceeds a predetermined value, electrical power to the data receiver is enabled. The recorded acceleration data may be used for injury analysis.