The U.S. Surgeon General's guidelines call for at least 30 minutes a day of moderate physical activity on most, if not all, days of the week.
But the pedometer and the surgeon general don't quite mesh.
The surgeon general's guidelines don't mention walking 10,000 steps, even though people have gotten the idea they do, said Guy C. Le Masurier, a doctoral student at Arizona State University East in Mesa. The figure does not equate to the Surgeon General's guidelines, he said.
The 10,000 steps concept is a Japanese import, created by a researcher who helped to promote pedometer-measured walking into a Japanese national movement.
"Ten-thousand is a good number but there's nothing magical in it," said Jim Hill, director of the Center for Human Nutrition at the University of Colorado Health Sciences Center.
"The best scientific evidence has demonstrated that a daily 30-minute brisk walk is important for health, not whether the step count reaches 10,000," Le Masurier wrote in the January-February issue of the American College of Sports Medicine's Health and Fitness Journal.
That's another case in which the surgeon general and the pedometer don't agree. Walking 30 minutes would require only about 3,000 steps, said Catrine Tudor-Locke, assistant professor of health promotion at the university. Walking 10,000 steps would take an hour and a half if the walker decided to do it all at one time, she said.
The average person probably does 5,500-7,500 steps in ordinary living, but does it sporadically, Tudor-Locke said.
And Le Masurier said meeting at least the surgeon general's minimums is important. When people amble in shorter bursts, he said, they don't sustain enough intensity to reach the moderate-activity targets.
The pedometer won't tell them, either. Pedometers count steps but not how much effort the walker is putting out.
"Brisk walking is being late for the bus or late for the meeting in the office," Le Masurier said. "It's hustling. Striding is another way to say brisk walking."
To measure this, Le Masurier had about 60 sedentary women wear, besides pedometers, accelerometers that could track changes in their velocity. He found that only about half of women who hit 10,000 or more steps were charging hard enough to meet the federal guidelines.
"We need to think about quality, not duration, of stepping," Le Masurier said.
However, there is some benefit to 10,000 steps, because only 17 percent of the women who were short of 10,000 steps met the standard, he said.
And for those who want to try, ordinary activity puts 10,000 steps within walking distance, Tudor-Locke said. The additional steps could be taken if the walker uses the surgeon general's recommended minimum as an exercise goal. A pedometer wouldn't be needed but a watch would be, because 30 minutes of walking would cover the ground, she said.
Not everyone is capable of jumping right on 10,000 steps. People who are sedentary take fewer than 5,000 steps a day and should ratchet up gradually, especially if they have health problems, Tudor-Locke said. How gradually would depend on the ability of the individual.
The point is to keep trying.
"I don't want people to think that, if they don't get to 10,000, they failed," Hill said. "It really matters where you are, and that you do more."