Exercise Benefits Pregnancies With High Blood Pressure
Contrary to popular thought, regular exercise before and during pregnancy could have beneficial effects for women that develop high blood pressure during gestation
Human physiology professor Jeff Gilbert said, summarizing a new study by his research team that appears in the December issue of Hypertension, a journal of the American Heart Association.
Gilbert's team observed that placental ischemia-induced hypertension in rats was alleviated by exercise and was accompanied by a restoration of several circulating factors that have recently been shown to be important in causing the high blood pressure associated with preeclampsia.
Hypertensive disorders of pregnancy,
such as preeclampsia, are the most common
dangerous pregnancy complications,
occurring in 5 percent to 8 percent of pregnancies.
Globally, preeclampsia and other hypertensive
disorders of pregnancy cause 76,000 maternal
and 500,000 infant deaths each year, conservatively,
according to the Preeclampsia Foundation.
"The data from our study raise the possibility
that exercise regimens if started before pregnancy
and maintained through most of gestation may be
an important way for women to mitigate the risk of preeclampsia.
There are certainly questions that remain,
such as when and how much exercise is required
and whether exercise training must begin before
pregnancy for these beneficial effects to occur.
Moreover, further studies are needed to determine
if it can safely be used as a therapeutic modality
for hypertension caused by insufficient blood flow
in the placenta.
But these results are certainly encouraging."
Professor, human physiology
University of Oregon
Previous clinical and epidemiological studies have long suggested that regular exercise before and during pregnancy reduced risk of preeclampsia but definitive mechanistic studies on the topic had been lacking until recently. Even though these findings are exciting, there are still safety concerns that need to be evaluated clinically and exercise continues to be discouraged in pregnancies complicated by high blood pressure.
Working in accordance with National Institutes of Health guidelines for animal use, Gilbert's team induced hypertension in pregnant rats by restricting blood flow to the rat placentas and monitored gestation after six weeks of exercise on activity wheels. Animals in test and control groups ran approximately 30 kilometers per week before pregnancy and approximately 4.5 kilometers per week during pregnancy.
Wheel running before and during pregnancy
reduced high blood pressure. It also improved
circulating concentrations of (1) vascular endothelial
growth factor and restored the balance between
that factor and (2) soluble fms-like tyrosine kinase 1*,
a kinases which restricts blood vessel
growth and function.
The study suggests that exercise lowers high blood
pressure by maintaining the balance between these
two factors that promote proper blood
vessel growth and function.
Exercise also improved endothelial cell function and reduced oxidative stress in the hypertensive rat. Fetal weight was not compromised by exercise and there were no obvious signs of fetal stress in rats with hypertension that exercised, Gilbert said.
•fms-like tyrosine kinase 1: a tyrosine kinase protein that disables proteins that cause blood vessel growth
The work was supported by a grant from the American Heart Association (10SDG2600040) and a five-year, $1.7 million research project grant to Gilbert from NIH (HL114096) to study preeclampsia.
About the University of Oregon
The University of Oregon is among the 108 institutions chosen from 4,633 U.S. universities for top-tier designation of "Very High Research Activity" in the 2010 Carnegie Classification of Institutions of Higher Education. The UO also is one of two Pacific Northwest members of the Association of American Universities.
Original article: http://uonews.uoregon.edu/archive/news-release/2012/11/exercise-benefits-found-pregnancies-high-blood-pressure