A breathing exercise apparatus comprises a chamber having a vent open to the atmosphere, a mouthpiece having an opening, a first member having a plurality of apertures positioned in the chamber between the opening in the mouthpiece and the vent, a second member having a plurality of apertures positioned in the chamber adjacent the first member, and a motor coupled to the second member and operable to move the second member with respect to the first member such that the apertures in the second member intermittently align with the apertures in the first member to vary the resistance a user experiences when both inhaling and exhaling through the apparatus.