UBC Theses and Dissertations
The influence of fitness level on the appearance of intrapulmonary arteriovenous shunting in healthy women Kennedy, Jill Margaret
It was hypothesized that intrapulmonary arteriovenous shunts would be recruited at lower exercise intensities in highly trained individuals, compared to untrained and moderately trained individuals. Twenty-four women with normal lung and cardiac function, completed a maximal exercise test on a semi-supine cycle ergometer, while agitated saline contrast echocardiography was performed. Subjects were considered either untrained (VO₂peak < 40ml/kg/min), moderately trained (VO₂peak 40-45 ml/kg/min) or highly trained (VO₂peak > 45 ml/kg/min), as determined by their performance on the exercise test. One subject did not shunt, four subjects demonstrated shunt pre-exercise, and eleven subjects demonstrated shunt in stage one of exercise. Twenty subjects continued to shunt immediately post-exercise, and seventeen subjects continued to shunt three minutes post exercise. These findings contrast with other studies in the upright cycling position, indicating an effect of body position. Percent of VO₂peak at shunt onset was not different between the groups, indicating no influence of training status. Cardiac output was not different between groups, potentially due to the inability of subjects to reach their true maximum on the exercise test. Peripheral oxygen saturation did not drop significantly during exercise and there was no difference in the lowest value reached by each group, indicating no limitations to pulmonary gas exchange.
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