Abstract: A ground reaction force plate apparatus and measuring system are provided. The apparatus includes a plate for receiving a force to be measured as applied by a subject to the plate and a plurality of load cells in an arrangement supporting the plate, each load cell being a single-axis sensor with the axis provided at an angle to a plane of the plate and oriented towards a centre of the plate. The load cells are configured to measure data relating to a force vector at the angled single-axis sensor when the subject applies a force to the plate. A data collection controller is provided for logging time series measurements of the load cells over a time in which the subject applies a force to the plate. The system applies machine learning processing to output the load cell measurements as a three-dimensional ground reaction force on the plate by a subject.