This comparative study tests Buteyko’s claims and explores the relationship between end-tidal carbon dioxide (ETCO) and BHT in addition to dysfunctional breathing, including the Nijmegen questionnaire, the Self Evaluation of Breathing Questionnaire, and thoracic dominant breathing pattern. The findings showed while BHT does not predict resting ETCO, it does correlate with breathing patterns in participants with abnormal spirometry. It is proposed that altered breathing pattern could assist in breathing symptoms like dyspnea. In addition, breathing therapies like the Buteyko Breathing Method could influence symptoms by enhancing the efficiency of the biomechanics of breathing. Courtney, R, Cohen, M, 2007. J Altern Complement Med. Volume 14, Issue 2, pp. 115-123. Read the Study