Give your lungs a safe, healthy workout with the Breathing Exerciser. This portable resistance trainer increases your lung stamina in just a few minutes per day. Simply sit down and breathe normally to strengthen your lungs. Increase the resistance with a twist of a knob as your breathing power improves. Helps reduce the feeling of breathlessness from asthma, bronchitis and emphysema. Also works for athletes, musicians and swimmers who wish to improve their respiratory performance.