Although exercise is generally considered to be good for people with high blood pressure, it may be risky for women who are pregnant.
Some studies suggest that exercise has benefits such as decreasing the risk of women developing preeclampsia, a condition that raises blood pressure to dangerously high levels but how this might happen has remained unknown.
New research using an animal model falls into the pro-exercise camp. It suggests that exercise before conception and in the early stages of pregnancy may protect a mother-to-be by stimulating two proteins that play a role in keeping blood vessels healthy.
The study was led by Dr. Jeffrey Gilbert while he was with the University of Minnesota Medical School.
In the study, female rats were separated into two – exercise and control groups, and later impregnated. The exercise group ran voluntarily on an activity wheel for six weeks prior to and during pregnancy, with running times and distances monitored weekly. The control group did not exercise. The team analyzed tissue samples taken from both groups late in their pregnancies.
The researchers found that the rats in the exercise group had higher levels of a circulating protein called vascular endothelial growth factor than those in the control group. and a pregnancy specific version of the protein called placental growth factor.
The researchers also saw that when VEGF increased, endothelial function increased. The endothelium is a thin layer of cells that line the inside of blood vessels. It reduces turbulence in blood flow, which allows blood to be pumped further with each heartbeat, thus taking stress off the heart.
The team also found that the rats in the exercise group had increased amounts of heat shock proteins (HSPs) compared to those that did not exercise. One HSP in particular play a vital role in maintaining the blood vessels of the heart. It works in sync with VEGF and nitric oxide to dilate blood vessels so that blood flows more freely and lowers blood pressure.
Increased expression of HSPs as a result of exercise could provide a preconditioning effect that may help protect against cellular damage in the placenta during pregnancies complicated by high blood pressure.
“There have been many studies about exercise and pregnancy, but not at the molecular level.” said Dr. Gilbert.
“We hope to learn whether stimulating these proteins with exercise before pregnancy or early during pregnancy can lower a woman’s risk for preeclampsia.”