Fig. 6. Changes in a hypothetical undesirable variable that can trigger gait transitions. As walking speed increases and the magnitude of a variable during walking exceeds that during running by the threshold , the walk–run transition occurs at the speed V_w-r (right vertical line). As running speed decreases and the magnitude of a variable during running exceeds that during walking by the threshold , the run–walk transition occurs at the speed V_r-w (left vertical line). According to this definition of the gait transition trigger, the walk–run transition occurs at a faster speed than the run–walk transition.