Abstract: This disclosure relates to a method for characterizing activation of an anatomical tissue subjected to contraction, aiming at providing a characterization of the contraction itself in a quantitative manner which is accurate and repeatable. The invention proposes an analysis of the activation of the anatomical structure based on instantaneous spectral contents of an activity signal from which an identification of peaks of dominant frequency characterizing the contraction throughout the anatomical tissue results. An evolution of a spatial distribution of peaks of dominant frequency throughout the anatomical tissue over time can also be monitored. The disclosure finds particular advantageous applications in provision of a mapping of activation of the anatomical tissue in order to identify a possible dysfunction, such as an arrhythmia in a cardiac tissue.