Three or four short, brisk walks throughout the day can help you watch your blood pressure more than one continuous episode of exercise.

"You might think, 'I don't have the time to go to the gym or work out for 40 minutes, but I might have the time to do 10 minutes here, 10 minutes here and another 10 minutes here,''' says Janet P. Wallace, a recreation expert at Indiana University.

Wallace, a kinesiology professor, studied the effects of how the benefits of exercise accumulating over time and from one continuous walk affect "prehypertension," the blood pressure readings that are between normal and high. Her research involved 20 people with prehypertension who walked on treadmills for 40 minutes in one swoop. On another day, they walked for times for 10 minutes, which took nearly four hours in total.

More, shorter walks did better

Wallace found that both accumulated and continuous walking decreased blood pressure by the same amount for all study participants. On average, their systolic blood pressure dropped about 5.5 points, and their diastolic blood pressure dropped 3.2. The drop is significant because a 5-point reduction in systolic blood pressure substantially reduces mortality and incidents of stroke and heart disease.

But the effect lasted for 11 hours in people who took four 10-minute walks, and only seven for those who took 40-minute walks, she explains.

 "We had no idea the short bouts would be better," Wallace says. "Most studies found in the literature report the long, continuous session as more effective for many variables."

You've heard about high blood pressure, but now . . .

Blood pressure measures how hard and efficiently the heart pumps blood through the body and is measured in millimeters of mercury (mm Hg).

Systolic blood pressure - the top number in the reading you get from the doctor - reflects how hard the heart works when it pumps blood. Diastolic blood pressure  -  the bottom number - reflects the resistance to the blood when the heart is not pumping.

Uncontrolled, high blood pressure can increase your risk for heart attack, heart failure, kidney failure, stroke and blindness.

"Normal" blood pressure is anything below 120/90.

However, more than 45 million people in the United States are thought to have prehypertension, which is treated only with diet and exercise. You have "prehypertension" when the systolic blood pressure ranges from 120-139 or the diastolic pressure ranges from 80-89.

The American Heart Association says your risk of getting a heart attack is tripled if you have prehypertension.