PowerBreathe special edition pink breathing trainer medium resistance is a scientifically proven Inspiratory Muscle Training (IMT) device. Sometimes referred to as a breathing training device - developed by leading scientists for improving the strength and endurance of the muscles used to breathe in, primarily the diaphragm and intercostals / rib cage muscles. As with any other muscle, respiratory muscles can be trained so that they are more resistant to fatigue. This resistance to fatigue results in reduced breathlessness and enhanced exericse tolerance. POWERbreathe Plus uses scientifically proven Pressure Threshold Training. This provides a specific and consistent pressure to train against. When breathing in through POWERbreathe the load calibrated spring provides the resistance.