Abstract: A wearable exercise and performance assessment system has a harness adapted to be attached to the torso of a wearer. The harness comprises a mount for releasably mounting an electronics module housing at a predetermined location on the torso. The electronics module housing comprises motion sensors. A processor processes received sensor data signals and outputs a resulting feedback signal to a performance feedback device. The processor comprises a sensor signal receiver arranged to receive motion sensor data signals over time from the motion sensors and to log the received signals with a synchronized time signal. One or more of the received sensor data signals is processed to identify data features therein indicative of repeated movements by the wearer and to delineate each repetition thereof. The processor applies the repetition delineation to one or more further received motion sensor data signal to determine a performance parameter for each individual repetition thereof.