When we overbreathe or hyperventilate, we lose valuable carbon dioxide. According to Prof. Buteyko, this hidden hyperventilation often goes undiagnosed. Acute (extreme) hyperventilation is obvious and the implications for the organism are disastrous. Hidden ventilation often goes unnoticed, even though asthmatics overbreathe by three or more times the recommended amount. Long term 'hidden hyperventilation' is the hinge upon which Buteyko's discovery and method are based. To test this for yourself, breathe very deeply for a few minutes. Take care as you may experience an asthma attack, blocked nose, dizziness, chest pains, palpitations, coughing and many other symptoms. Breathing shallowly can reverse these symptoms within a few minutes.