Mild exercise may not help hypertension.

An occasional power walk may prove relaxing, but people aiming to reduce their blood pressure may need to rev up their exercise program. Although previous studies linked physical fitness to reduced blood pressure (SN: 6/1/91, p.342), a new study suggests that moderate exercise has a negligible effect on mild hypertension.

The four-month investigation involved 99 non-obese, mildly hypertensive men and women, with systolic blood pressures of 140 to 180 millimeters of mercury (mm Hg) and diastolic blood pressures of 90 to 105 mm Hg. Persons assigned to walk 35 minutes three times a week did not significantly lower their blood pressure compared with those who weight-trained several times weekly or did no exercise, according to a report published in the Oct. 16 JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION.

"That was a big surprise," says study director James A. Blumenthal of Duke University in Durham, N.C. His group also did not expect the six- to eight-point average drop in blood pressure measured in all three experimental groups. This across-the-board improvement probably reflects the positive effect of being part of a health study, he says.

The research team took multiple blood pressure readings of study participants in a variety of settings, closely supervised their activities, and evaluated changes in their cardiorespiratory fitness. Walkers who showed the greatest improvement in aerobic fitness also reduced their blood pressure the most.

Blumenthal and his co-workers conclude that more vigorous, frequent exercise might effectively treat mild hypertension, but they discourage physicians from prescribing moderate exercise in place of drug therapy.