Grant: Doctoral Award - Frederick Banting and Charles Best Canada Graduate Scholarships

Current guidelines encourage pregnant women to exercise. During exercise, the sympathetic (fight/ flight) nervous system plays an important role in delivering blood flow to the working muscles. We have shown that the effects of the sympathetic activity are blunted in pregnancy. This may promote blood flow to the fetus. We believe this effect may also favor delivery of blood to the fetus during exercise. How the sympathetic nervous system regulates blood flow to the working muscles and the fetus during exercise in pregnancy has not been explored. Further, we do not know if/how exercise training during pregnancy affects this response. We propose to test the control of blood flow during hand-grip exercise in healthy pregnant women. We will assess this response before and after 20 weeks of aerobic exercise training during pregnancy compared to women who are not enrolled in exercise training. We hypothesize that the increase in sympathetic activity during exercise will have a lesser effect on muscle blood flow in pregnant women, favoring blood flow to the fetus, and that exercise training will improve this relationship. We will randomly assign 60 pregnant women into exercise training or control groups. The exercise training will consist of aerobic activity that will occur for 40 minutes, 3 times per week. Prior to and after training, we will continuously measure heart rate, blood pressure, blood flow in the arm and to the fetus, and sympathetic activity during 2-minutes of static hand-grip at 30% of maximum contraction (known to increase sympathetic activity). Changes in sympathetic activity and blood flow (in the arm and to the fetus) will be assessed to establish if changes in blood flow regulation during exercise are associated with exercise training in pregnancy. We believe these data will be important for understanding acute and chronic exercise responses during pregnancy and will help determine how blood flow is distributed to support fetal development.