You'll go the extra mile for good health if you know how far you're going, say researchers at the Stanford University School of Medicine.

When people wear pedometers -- inexpensive devices clipped to a pocket or a belt that measure how many steps are taken -- they walk about 2,100 steps more each day than they did before they wore the pedometer, according to a study published today in the Journal of the American Medical Association.

Dr. Dena Bravata and her colleagues examined 26 studies of pedometer use. They involved 2,767 people, most overweight females.

The 2,100 additional steps amount to about a mile a day, a 27 percent increase in physical activity for the pedometer users studied, Dr. Ravata said.

The pedometer users lost weight and lowered their blood pressure significantly, Dr. Ravata said.

Dr. Ravata said she was surprised by how much wearing a pedometer increased a person's willingness to exercise. University of Colorado obesity expert James Hill was not.

"We can get pretty amazing increased physical activity by using pedometers," he said.

For outdoor lovers only

Like to hike, bike or camp? You can win some cool prizes just by demonstrating that you participate in outdoor activities.

Epic, the Web magazine of outdoor equipment manufacturer North Face, is offering prizes such as tents, sleeping bags and backpacks to people who show them proof they participate in at least of four of 17 outdoor activities listed on its Web site, www.exploreepic.com.

Among the activities are running in a sponsored race, hiking, canoeing or kayaking, climbing and mountain biking.

Other activities that could win prizes are planting a tree, picking up garbage in a park or along a trail, and hanging up clothes to dry.

To be eligible, have snapshots taken of yourself performing any four of the activities listed on the Web site, and post the photographs at forums.exploreepic.com by Dec. 15. Forty winners will be selected from a random drawing.