Abstract Non-linear transient behaviour of flexible structures requires numerical integration of the system's equations of motion. A simplified method for identifying the impulse response function, while avoiding this integration, is presented here. The impulse response function obtained is time dependent and is a characteristic of the global system, remaining valid when reasonable perturbations are applied to external data. Application of this method to the swing of a golfer gives satisfactory results. The implementation of the method as a solution to an inverse dynamics problem, the optimisation process, validation with experimental data, and a potential biomechanical application is discussed.