Abstract: A pulmonary muscle trainer consisting of a tubular body having a poppet valve dividing the body into two sections. The poppet is adjustably biased into the closed position, whereby inspiration of a given intensity will be sufficient to overcome the bias and allow air flow through the unit. The poppet is supplied with a one-way valve element to permit the user to create an unrestricted expiration air flow to allow a breathing rhythm to be established. In a preferred embodiment bias is maintained on the poppet by a spring whose compression is adjustable by means of a collar manually positionable within the body of the unit. By the use of the poppet a constant threshold pressure load may be applied.