November 20, 2007 - By Michelle Brandt
STANFORD, Calif. - The pedometer, a small, inexpensive device that counts the number of steps walked per day, could be key to ramping up a person's physical activity.
Researchers at the Stanford University School of Medicine have found that the use of a pedometer is associated with significant increases in physical activity and weight loss and improvements in blood pressure.
"Much to my surprise, these little devices were shown to increase physical activity by just over 2,000 steps, or about 1 mile of walking per day," said the study's lead author, Dena Bravata, MD, MS, a senior research scientist in medicine. "This goes a long way toward helping people meet the national guidelines for daily physical activity."
Bravata's study, which is the first published review of literature on the effectiveness of pedometers, is published in the Nov. 21 issue of the Journal of the American Medical Association.
Although two-thirds of U.S. adults are overweight or obese, according to the Centers for Disease Control and Prevention, only 45 percent of Americans get enough physical activity. Guidelines from the Department of Health and Human Services recommend that adults get at least 30 minutes of daily physical activity. Several organizations, such as the nonprofit Shape Up America founded by former U.S. Surgeon General C. Everett Koop, MD, recommend that adults walk 10,000 steps each day.
In recent years, pedometershave emerged as a popular tool that's easy to use (clipped to a pocket or waistline) to count steps walked per day. The devices are affordable, with many brands selling for as little as $10 or $15. Some employers, like Chevron Corp., even provide pedometers for free to workers who pledge to walk a certain number of steps each day.
Bravata, a general internist, said she was curious whether she should recommend pedometers to her patients, many of whom are not active enough. "Improving health behaviors is the No. 1 thing I discuss during my patients' routine visits, and I'm constantly seeking ways to get them to exercise more," she said.
To evaluate the effects of pedometers on physical activity and health outcomes, Bravata and her colleagues reviewed more than 2,000 articles and found 26 studies - 18 observational studies and eight randomized trials - that looked at the use of pedometers as a tool to motivate physical activity. A total of 2,767 people participated in the studies; most participants were female, overweight and relatively inactive before they started their walking program.
The walking programs evaluated in the studies varied considerably: 23 included a step goal and diary, in which participants recorded their daily activity; 17 included physical activity counseling; and five took place in the workplace. The mean study duration was 18 weeks.
Bravata and her team found that pedometer users in the randomized trials increased their physical activity by 2,491 steps per day more than participants who did not use pedometers. Among the observational studies, pedometer users increased their physical activity by 2,183 steps per day over baseline.
"Just over 2,100 steps might not sound that much, but it equates to a 27 percent increase in physical activity - which is really astounding," said Bravata.
One person who wasn't surprised by the finding is James Hill, PhD, an obesity expert at University of Colorado. "It fits with everything we've seen; we can get pretty amazing increased physical activity by using pedometers," said Hill, who co-founded America on the Move, a national initiative that encourages people to add 2,000 steps a day to what they already are doing.
Dena Bravata did a review of studies on pedometers to see if she should recommend them to patients.
When looking beyond increased steps, Bravata's team found that pedometer users lost weight: their body mass index - a measure of body fat based on height and weight - decreased by 0.4. (For a 5-foot-6 person who initially weighed 195 pounds, that would be 2.5 pounds lost.)
They also saw their systolic blood pressure (the upper number of the two values) fall by 3.8 mm Hg. Bravata said she considered this decrease quite significant, especially because the baseline blood pressure of the pedometer users was not that high. She noted that a reduction of 2 mm Hg is associated with a 10 percent reduction in stroke mortality and a 7 percent reduction in death from vascular causes.
The researchers also evaluated specific components of the walking programs and found that having a step goal was a key predictor of increased physical activity. "People don't always achieve it, but just having a goal seems to help them stay motivated and improve their physical activity," she noted.
Bravata pointed out that this study does have limitations. Only 15 percent of study participants were male, for example, and the mean study duration was only 18 weeks. She said more randomized, controlled studies on longer-term pedometer use are needed.
In the meantime, Bravata hopes her findings will encourage physicians to recommend pedometers to their sedentary patients. And Hill hopes this demonstrates to people that health can be improved with just simple changes. "Nothing is simpler than getting a pedometer," he said.
Bravata's co-authors, who were all at Stanford at the time of the study, are Crystal Smith-Spangler, MD; Vandana Sundaram, MPH; Allison L. Gienger; Nancy Lin, ScD; Robyn Lewis, MA; Christopher D. Stave, MLS; Ingram Olkin, PhD and John R. Sirard, PhD. This project was supported by a grant from the National Institute on Aging through the Stanford Center on the Demography and Economics of Health and Aging.
Stanford Medicine integrates research, medical education and health care at its three institutions - Stanford University School of Medicine, Stanford Health Care (formerly Stanford Hospital & Clinics), and Lucile Packard Children's Hospital Stanford. For more information, please visit the Office of Communication & Public Affairs site at http://mednews.stanford.edu.