Circulatory effects of apnoea in elite breath-hold divers

Acta Physiol (Oxf). 2009 Sep;197(1):75-82. doi: 10.1111/j.1748-1716.2009.01982.x. Epub 2009 Feb 28.

Abstract

Aim: Voluntary apnoea induces several physiological adaptations, including bradycardia, arterial hypertension and redistribution of regional blood flows. Elite breath-hold divers (BHDs) are able to maintain very long apnoea, inducing severe hypoxaemia without brain injury or black-out. It has thus been hypothesized that they develop protection mechanisms against hypoxia, as well as a decrease in overall oxygen uptake.

Methods: To test this hypothesis, the apnoea response was studied in BHDs and non-divers (NDs) during static and dynamic apnoeas (SA, DA). Heart rate, arterial oxygen saturation (SaO(2)), and popliteal artery blood flow were recorded to investigate the oxygen-conserving effect of apnoea response, and the internal carotid artery blood flow was used to examine the mechanisms of cerebral protection.

Results: The bradycardia and peripheral vasoconstriction were accentuated in BHDs compared with NDs (P < 0.01), in association with a smaller SaO(2) decrease (-2.7% vs. -4.9% during SA, P < 0.01 and -6% vs. -11.3% during DA, P < 0.01). Greater increase in carotid artery blood flow was also measured during apnoea in BHDs than in controls.

Conclusion: These results confirm that elite divers present a potentiation of the well-known apnoea response in both SA and DA conditions. This response is associated with higher brain perfusion which may partly explain the high levels of world apnoea records.

MeSH terms

  • Adaptation, Physiological*
  • Apnea / blood*
  • Athletes
  • Blood Flow Velocity / physiology
  • Brain / blood supply*
  • Brain / physiology
  • Carotid Arteries / physiology
  • Cerebrovascular Circulation / physiology*
  • Diving / physiology*
  • Humans
  • Male
  • Regional Blood Flow
  • Respiratory Mechanics
  • Young Adult