Human locomotion is typically studied independently ofthe cardiovascular system, although the two areintrinsically linked. An example of their interaction iscardiac-locomotor coupling (CLC), which refers to theentrainment of heart rate (HR) and step rate (SR) duringrhythmic exercise at a 1:1 ratio. Actively synchronizingthe stepping with each diastole of the cardiac cycle, hasbeen shown to provide improved cardiometabolicefficiency, demonstrated by a decrease in HR and inventilation [1]. Active CLC can therefore be one way toimprove hemodynamic efficiency, ensuring greaterendurance performances. Previous studies investigatedthe presence of CLC in laboratory settings whereasobservations during daily activities are still lacking. Wedo not know if and when CLC occurs physiologically.The aim of this study is to investigate the extent and theprobability of CLC during unsupervised daily activitiesin contrast to random chance.