Exercise-induced arterial hypoxaemia in athletes - A review

During exercise, healthy individuals are able to maintain arterial oxygenat ion, whereas highly-trained endurance athletes may exhibit an exercise-indu ced arterial hypoxaemia (EIAH) that seems to reflect a gas exchange abnorma lity, The effects of EIAH are currently debated, and different hypotheses h ave been proposed to explain its pathophysiology. For moderate exercise, it appears that a relative hypoventilation induced by endurance training is i nvolved. For high-intensity exercise, ventilation/perfusion ((V)over dot (A )/(Q)over dot) mismatching and/or diffusion limitation are thought to occur , The causes of this diffusion limitation are still under debate, with hypo theses being capillary blood volume changes and interstitial pulmonary oede ma, Moreover, histamine is released during exercise in individuals exhibiti ng EIAH, and questions persist as to its relationship with EIAH and its con tribution to interstitial pulmonary oedema, Further investigations are need ed to better understand the mechanisms involved and to determine the long t erm consequences of repetitive hypoxaemia in highly trained endurance athle tes.