A runner for a hydraulic turbine or pump includes a plurality of blades, each blade being defined by a pressure surface, an oppositely facing suction surface, a leading edge and a spaced apart trailing edge. At least one blade has a device for supplying a flow of oxygen containing gas to the trailing edge of at least one of the blades. The profile of the suction side surface of the blade along a cross section through a point P1 and a point P2 is concave. The point P1 is located on the suction side surface of the trailing edge where an opening is located, the point P2 is spaced apart from the point P1 by less than 3% of the runner outlet diameter D and the point P2 is located upstream of the point P1 on a line perpendicular to the trailing edge starting at the point P1.