The Buteyko method was developed by Konstantin Buteyko. As a medical student in 1952 he observed that as people approached they began to hyperventilate.
This hyperventilation was believed to be a major factor in the cause of death. He believed that 90% of the population was over-breathing.
By over-breathing excessive carbon dioxide was being lost reducing the effectiveness of breathing which means that further over-breathing occurs to try and enable more oxygen to be gained less efficiently.
By learning to reduce the volume of breathing can be normalized as carbon dioxide levels are returned to normal.