Millions of Americans walk, run, and bike regularly—thinking that the exercise they do helps keep their blood pressure in check. But, for older Americans, staying fit may only go so far, according to new research from the Johns Hopkins School of Medicine and the National Institutes on Aging.

What they wanted to know: Does exercise reduce high blood pressure in older adults?

What they did: The researchers split a group of about 100 people ages 55 to 75 who had mildly high blood pressure into two groups. All the volunteers had a systolic blood pressure of 130 to 159 or a diastolic pressure of 85 to 99. While both groups received packets with federal guidelines for exercise and diet to help control blood pressure, half the participants also participated in three supervised workout sessions a week. At those hour or longer sessions, the participants did weight training and aerobic exercise, either a treadmill, stationary bike, or stairstepper. The researchers measured all of the participants' blood pressures at the beginning of the study, and then again after the fitness group had been working out for six months.

What they found: Both groups lowered their blood pressure over the six months of the study. Exercisers lost more weight and gained more muscle than the stationary group, but only their diastolic, not systolic, blood pressure improved more than the stationary group. Blood pressure is made up of two numbers. Systolic, the first and higher number, is the pressure in your arteries when your heart beats, and the second, diastolic, is the pressure in your arteries when your heart is at rest. An increase in either number can mean high blood pressure. The researchers speculate that they did not see a significant change in systolic blood pressure because as people age, their arteries harden, which can increase systolic blood pressure and which cannot be helped through exercise. They did find, however, that the people who lost more fat reduced their blood pressure the most.

What it means to you: Older adults may need to do more than just exercise to improve their blood pressure. However, because decreasing body fat reduced blood pressure, this study should not be taken to mean that exercise does not help maintain a healthy heart.

Caveats: The stationary group, perhaps because they knew they were part of a study, seemed to step up their efforts to stay healthy. So, they may have exercised more or eaten better than they otherwise would have, making it harder at the end of the study to compare the effects of exercise versus no exercise.

Find out more: The National Institutes of Health has a succinct definition of high blood pressure on its Medline Medical Encyclopedia website.

For a more comprehensive explanation, including a quiz to test whether you are at risk, check out the American Heart Association.

Read the article: Stewart, K.J. et al. "Effect of Exercise on Blood Pressure in Older Persons." Archives of Internal Medicine. April 11, 2005, Vol. 165, No. 7, pp.756–762.

Article online: http://archinte.ama-assn.org