Hello, I bought my condition improve this mask during the pit. In general I can say that the mask has especially during the punching bag or punch training helped me "to breathe properly." There are also some videos in Youtube where told that is the mask prevents you breathe through the mouth and exhale through the nose. That's bullshit, you can just breathe wrong as even without her having the mask. There are 3 valves, the two sides to inhale the exhale in the center to. The valves have a non-return diaphragm so that is left either in or out only in one direction the air. For jogging I pull the mask also, although I must say that at the beginning it is a bit strange to walk with her. But after several grinding the diaphragm used to it and you can also have more than 6km jog with her. Of course, with the mask not achieved what top athletes reach for example in the mountains during training. Because the oxygen depleted air in the mountains brings the body to produce more red blood cells which are responsible for oxygen transport, which of course positively auswirkt.Und on the condition itself that is achieved only after several weeks in the mountains. But as I said, it is still a good workout for the diaphragm and thus helps a little to improve the condition.