Breathing device, app and interaction therebetween

A method for adjusting the rebreathing ratio (RBR) of a breathing device with an adjustable RBR and a computer configured to automatically determine whether to change the RBR based on a user's response to a questionnaire, the method comprising:

• providing a breathing device comprising:
• a mouthpiece forming a breathing channel to form a connection between a first end and a second end of the mouthpiece, the first end being configured for a user breathing into the mouthpiece through a breathing opening;
• an at least partly flexible rebreathing air chamber arranged in fluid communication with the second end of the mouthpiece, thereby being in fluid connection with the breathing channel through the second end of the mouthpiece, the rebreathing air chamber being formed by at least partly flexible wall section(s);
• a wall member pivotally connected to the second end of the mouthpiece and forming part of the rebreathing air chamber;
• one or more through-going openings provided in the wall member at the second end of the mouthpiece, allowing fluid communication between the rebreathing air chamber and the surrounding atmosphere, said one or more through-going openings being re-closeable or adjustable in size;
• the user breathing through the breathing device;
• executing a questionnaire containing questions relating to the user's response to the use of the breathing device during use of the breathing device,
• in response thereto determining by use of the computer whether to change the RBR, and
• when the RBR is determined to be changed, signalling to the user a new setting for the breathing device.