"The biggest problem for most people is they don't have the time," said Janet P. Wallace, professor in the Department of Kinesiology at the IU School of Health, Physical Education and Recreation. "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.' Four 10-minute walks would be ideal."
Wallace's study compared the effect of accumulated versus continuous physical activity on prehypertension, an elevated blood pressure level that typically progresses to hypertension or high blood pressure. Uncontrolled, high blood pressure can increase a person's risk for heart attack, heart failure, kidney failure, stroke and blindness. More than 45 million people in the United States are thought to have prehypertension, which is treated only with diet and exercise.
Wallace's study found that both forms of exercise, accumulated and continuous, decreased study participants' blood pressure by the same amount. The effect lasted for around 11 hours in the group who took four 10-minute walks, compared to seven hours for the group that walked continuously for 40 minutes.
"We had no idea the short bouts would be better," Wallace said. "Most studies found in the literature report the long, continuous session as more effective for many variables."
Wallace's findings appear in the September issue of the Journal of Hypertension. Co-authors are Saejong Park, a doctoral student in the Department of Kinesiology, and Lawrence D. Rink, a clinical professor of medicine at the IU School of Medicine.
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 reflects how hard the heart works when it pumps blood. Diastolic blood pressure reflects the resistance to the blood when the heart is not pumping. A person has prehypertension when the systolic blood pressure ranges from 120-139 mm Hg or the diastolic pressure ranges from 80-89 mm Hg.
The randomized crossover study involved 15 men and five women with prehypertension. They walked on a treadmill continuously for 40 minutes and on another day, four times for 10 minutes over the course of 3.5 hours. On average, their systolic blood pressure dropped 5.4-5.6 mm Hg and their diastolic blood pressure dropped 3.2 mm Hg. The drop is significant because a reduction of 5 mm Hg in systolic blood pressure has been reported to substantially reduce mortality and to reduce the incidence of stroke and coronary heart disease.
The prehypertension research was funded in part with a grant from the Gatorade Sports Science Institute. Wallace has begun a similar study involving people with hypertension.
Source: Indiana University