Exercise May Help Reduce Salt's Effect On Blood Pressure

The more exercise you do, the less of an effect salt may have on your blood pressure, a new study suggests.

People who said they exercised the most in the study had a 38 percent lower risk of being sensitive to a high-salt diet, compared with people who didn't exercise at all, the study said.

For the study, researchers defined someone as salt-sensitive if his or her average systolic blood pressure (the top number on a blood pressure reading, indicating pressure from the heart contracting) increased 5 percent or more when switching from a low-salt diet of 3,000 milligrams per day to a high-salt diet of 18,000 milligrams per day.

However, even the amount of salt in the low-salt diet in the study is twice the salt intake that the AHA recommends.

Researchers from the Tulane School of Medicine in Louisiana used health data from 1,906 rural Chinese adults, with an average age of 38, who were part of the Genetic Epidemiology Network of Salt Sensitivity. None of the study participants were on blood pressure medications, and all were asked to report whether their levels of physical activity were considered high or low.

People in the study were first put on a 3,000-milligrams-per-day diet for seven days, and then put on an 18,000-milligrams-per-day diet for seven days. Their blood pressure was taken nine times throughout the study to determine their salt sensitivity when going from the low-salt diet to the high-salt diet .

People who reported being the least active had an average increase in blood pressure of 5.27 millimeters of mercury (mm Hg) when going from the low-sodium to high-sodium diet, the study said. But those who reported being the most active had an average increase of 3.88 mm Hg when switching diets.

A systolic blood pressure of 120 mm Hg or a diastolic (the bottom number of a blood pressure reading, which is the pressure of the heart relaxing between beats) pressure of 80 mm Hg is considered healthy for adults, according to the AHA.

However, a person is considered prehypertensive if his or her systolic pressure is between 120 mm Hg and 139 mm Hg, and the diastolic pressure is between 80 to 89 mm Hg, the AHA said.

Because the study was in rural Chinese adults, it's hard to say whether the results can be replicated in a Western population, said William Farquhar, an associate professor kinesiology and applied physiology at the University of Delaware, who was not involved with the study.

However, the study results are strong because of the large population, he said.

"These types of studies are important and tend to stimulate additional research," Farquhar told MyHealthNewsDaily.

The study was presented this week at a meeting of the American Heart Association.

Pass it on: Being physically active can decrease the negative effects of salt on your blood pressure.

Follow MyHealthNewsDaily staff writer Amanda Chan on Twitter @AmandaLChan.

Amanda Chan
Amanda Chan was a staff writer for Live Science Health. She holds a bachelor's degree in journalism and mass communication from the Walter Cronkite School of Journalism and Mass Communication at Arizona State University, and a master's degree in journalism from Columbia University.