Abstract

Research examining the heart rate response of humans to apnoea and apnoeic immersion in water has tended to produce equivocal results. Controversy exists in relation to the existence and onset, course and ultimate extent of apnoeic bradycardia, either at rest or during exercise. The reduction in heart rate that has been observed in response to apnoea and apnoeic immersion is considered by some to be a component of an oxygen conserving mechanism termed the mammalian dive reflex. Doubt has been expressed, however, as to whether humans do possess the complex cardiovascular response evident in diving mammals. A bradycardial response to apnoea at rest is reasonably well established. Reports conflict with regard to apnoeic responses to exercise in both terrestrial and aquatic environments, and for the temporal onset of apnoeic bradycardia in general, and the time course required for the maximal development of the response. Verf.-Referat