Walking 10,000 steps in a day has become a standard mark of a healthy lifestyle, endorsed by activity trackers like the Fitbit or Jawbone, as well as weight-loss websites and the American Heart Association.

But that number — 10,000 steps — wasn’t established by any scientific study, says Catrine Tudor-Locke, director of the Walking Behavior Research Laboratory at the Pennington Biomedical Research Center.

“It’s not as if you hit one number and the skies open up and the angels sing,” Tudor-Locke says.

In the early 1960s, before the Tokyo Olympics, a Japanese company created a pedometer — a mechanical step counter — called the Manpo-Kei. The name roughly translates into “10,000-step meter,” says Tudor-Locke, and Manpo-Kei became a slogan, like Nike’s “Just do it.”

“It resonated with people, and it was very big in Japan,” she says, “and people were Manpo-Keiing all over the place.”

Scientists studied the phenomenon and found that, yes, walking 10,000 steps a day is good for you.

But the real minimum an adult needs is about 7,500 steps, Tudor-Locke says. This includes about 4,500 steps throughout the day with about 30 minutes of moderate to vigorous physical activity, which is the minimum recommended.

A sedentary adult walks fewer than 5,000 steps each day, she says.

Tudor-Locke advises most adults to seek the amount of activity they need to stay healthy.

And 10,000 steps can be a good first goal.

It seemed like a lot to Pam Shaffer.

A former aerobics instructor, Shaffer bought a Fitbit — a computerized activity tracker worn on the wrist — and it recommended she walk that many steps every day.

“I didn’t know how many steps I did,” says Shaffer, 53.

Between morning, lunchtime and afternoon walks on her breaks from the office at Associated Grocers, she was soon blasting through 10,000 steps, hitting 15,000 or more.

“I’m doing more because I’m competitive,” she says. “I have the goal of 10,000, but generally at noon I’m over.”

And Tudor-Locke says that’s a good thing.

“Don’t get me wrong. The science does show that 10,000 is good,” she says. “It’s laudable. But 12,000 is better, and 17,000 is better and so on.”

The average Amish man walks 18,000 steps, she says, because their culture eschews machines and they mostly rely on their own feet for transportation. They also have fewer health problems and lower rates of obesity, Tudor-Locke says.

“At this point, there has not been a number that is thought to be detrimental to health,” she says. “Our bodies are pretty savvy, and they know when to rest.”

When Michael Hanley, 31, bought a Fitbit late last year, he was interested in improving his health.

His blood pressure and cholesterol were high, and he knew he couldn’t run. Walking 10,000 steps seemed attainable.

“It really helped just in the starting, initial phase,” says Hanley, a 31-year-old manager for Ryder trucks who lives in Baton Rouge. “This had to be my minimal goal — 10,000 steps a day.”

Since February, he has lost 40 pounds, and he has started running, first training for a 5-kilometer run, now working on a 10K.

“It really all started with walking and hitting 10,000 steps,” he says. “It all went from there.”

Walking — whether it’s 7,500 steps or 15,000 — is the simplest way to prevent obesity and improve the health of a large population, Tudor-Locke says.

“From a public health point of view, it’s important to get the least active people active,” she says. “I think that’s where the big benefit comes from, working with the overweight, the people living with chronic diseases, the older people. That’s where (walking) really, really shines.”