Progress has been made in laser speckle contrast imaging (LSCI) of microcirculatory blood flow for biology and medicine. However, the underlying reason for occurrence of movement artefacts (MA) that compromises effective use of LSCI remains largely unexplored. Here, employing a dual-camera setup for both speckle imaging and movement tracking, we validate our analytical model that is based on optical Doppler effect for predication of speckle contrast drop as a function of applied translational speed. We perform both motorized and handheld experiments where planar and scrambled wave illumination schemes have been examined. Experimental data points fairly match the theoretical predictions. These findings indicate that the vision-based movement detection during handheld LSCI is a preferable option. Moreover, the proposed analytical model is promising for further exploration of MA in order to realize a reliable handheld LSCI.