There is provided a method and an apparatus for performing the method, the method comprising: obtaining cardiac output power data on a user； obtaining kinetic data characterizing physical exercise intensity of the physical exercise performed by the user； detecting that a measured cardiac output power exceeds a first threshold or that physical exercise intensity changes according to a rate exceeding a second threshold； upon said detecting, determining a synthetic cardiac output power parameter based at least partly on the kinetic data； and outputting the synthetic cardiac output power parameter.
