A system for a racket comprises an inertial sensor for coupling to the racket, a processor connected to the inertial sensor, and a memory device connected to the processor. The inertial sensor includes an accelerometer array with three degrees of freedom in acceleration and a gyro array with three degrees of freedom in rotation. The processor is configured to generate stroke profiles describing acceleration and rotation of the racket based on signals from the accelerometer and the gyro arrays, and the memory device is configured to store the stroke profiles.