Breathing training device adapters and associated methods are disclosed herein. According to an aspect, a breathing training device adapter includes a housing comprising a first end and a second end that each define an opening. The housing defines an interior space that extends between the first end and the second end to enable gas flow between the opening of the first end and the opening of the second end. The adapter may include a first connector configured to operatively connect the opening of the first end to a breathing training mouthpiece as well as a gas valve operatively connected to the housing to provide controlled gas flow between the interior space of the housing and outside the housing. Further, the adapter may include a second connector configured to operating connect the opening of the second end to a breathing training device.
