Exercise-induced hypoxaemia in highly trained XXXX .

@entity1 @entity26 @entity2587 @entity3316 @entity432
Traditionally, the pulmonary system has not been considered the limiting factor in determining maximal @entity26 uptake (VO2max) in healthy individuals since arterial @entity26 -haemoglobin saturation is thought to remain high during intense exercise. However, there appears to be a major exception to this rule. Recent evidence suggests that @entity432 results during heavy exercise in well trained individuals with a high VO2max. Further, the degree of arterial desaturation is inversely related to VO2max. This exercise-induced hypoxaemia does not appear to be due to @entity3316 although @entity2587 who have limited hyperventilation seem to exhibit the lowest arterial @entity26 -haemoglobin saturation. A significant venoarterial shunt has been ruled out as a primary cause of the hypoxaemia based on both experimental and theoretical considerations. Therefore, it appears that the exercise-induced hypoxaemia seen in highly trained @entity2587 during heavy exercise is primarily due to diffusion limitations and ventillation-perfusion inequality. It is postulated that incomplete diffusion in the healthy lung may be due to a rapid red blood cell transit time through the pulmonary capillary. In summary, recent findings suggest that the limits of the @entity1 pulmonary system may be reached or even exceeded during intense exercise in some individuals. In light of these findings the role of the pulmonary system as a limiting factor during maximal exercise in the highly trained endurance athlete warrants further investigation.
