Exercise-induced hypoxemia that may occur in elite endurance athletes during heavy exercise is likely due to
A) overt lung disease.
B) reduced alveolar ventilation due to exercise-induced asthma.
C) a right-to-left shunt.
D) a diffusion limitation secondary to a rapid red blood cell transit time.

Question

Exercise-induced hypoxemia that may occur in elite endurance athletes during heavy exercise is likely due to 
A) overt lung disease.
B) reduced alveolar ventilation due to exercise-induced asthma.
C) a right-to-left shunt.
D) a diffusion limitation secondary to a rapid red blood cell transit time.

Quizplus · Accepted Answer

Exercise-induced hypoxemia in elite endurance athletes is likely caused by a diffusion limitation secondary to a rapid red blood cell transit time. This occurs because during intense exercise, there is an increase in cardiac output and blood flow to muscles, which reduces the amount of time that red blood cells spend in the pulmonary capillaries, leading to less time for diffusion of oxygen from the alveoli into the blood. This is not typically due to overt lung disease, exercise-induced asthma, or a right-to-left shunt.

Exercise-Induced Hypoxemia That May Occur in Elite Endurance Athletes During