Adaptive Responses to Hyperventilation

¹ From the Department of Physiology and Biophysics, Air University, School of Aviation Medicine, United States Air Force, Randolph Air Force Base, Texas

The possibility and nature of adaptive mechanisms to chronic hyperventilation were investigated. A standardized hyperventilation test procedure was employed to reveal alterations of psychomotor performance in relation to cardiovascular, respiratory, and biochemical responses during gradually increased hypocapnia under various experimental conditions. After normal control patterns had been established, the hypocapnic tolerance of six individuals was retested 1) after 2 weeks' training in hyperventilation, 2) after 8 weeks' training for physical conditioning, 3) during a state of severe physical fatigue, 4) at an altitude of 14,000 feet after sufficient acclimatization and 5) following return to sea level. Hypocapnia tolerance was substantially improved by training in hyperventilation. However, the adaptive mechanisms were apparently not of biochemical nature and are still a matter of speculation.