My teenage daughter swims further than most people walk in a given day. She gets up at 5 a.m. to swim for two hours with her high school swim team and then does it again at 5 p.m. with our local YMCA swim team. In between she does strength and conditioning moves recommended by her coaches. Yet, when she first got her FitBit earlier this year, she was bummed to see that according to the tracking device's standards, she wasn't meeting her fitness goals for each day because she wasn't taking the recommended 10,000 steps.

You've probably heard it suggested that you need to move more throughout the day, and as a general rule of thumb, that "more" is often defined as around 10,000 steps. With many Americans tracking their steps via the explosion of new fitness-tracking wearables, or even just by carrying their iPhone, more and more people use the 10,000-step rule as their marker for healthy living.

Dr. Greg Hager, professor of computer science at Johns Hopkins, decided to take a closer look at that 10,000-step rule, and he found that using it as a standard may be doing more harm than good for many.

Where did that number come from, anyway?

People walking down a busy street People come in all kinds of shapes and sizes, so it's silly to assume that one step goal will work for everyone. (Photo: IR Stone/Shutterstock)

Have you ever wondered why we are all told to shoot for 10,000 steps a day?

"Turns out in 1960 in Japan they figured out that the average Japanese man, when he walked 10,000 steps a day burned something like 3,000 calories and that is what they thought the average person should consume so they picked 10,000 steps as a number," Hager said in his presentation at the annual meeting of the American Association for the Advancement of Science.

According to Hager, asking everyone to shoot for 10,000 steps each day could be harmful to the elderly or those with medical conditions that make it unwise for them to jump into that level of exercise, even if it's walking. He also noted that those with shorter legs have an easier time hitting the 10,000 step goal because they have to take more steps than longer-legged people to cover the distance. The bottom line is that 10,000 steps may be too many for some and too few for others.

Hager isn't saying we should abandon step goals and fitness trackers altogether; it's great that more people are paying attention to how much they move their bodies each day. But the key is in finding the step goal that matches your individual health and fitness goals. That might mean having a conversation with your doctor, physical therapist, or fitness instructor and then using your fitness tracker to help you achieve those goals — not trying to achieve some blanket goal set by your tracker.

On the other extreme

A 2017 study looked at postal workers in Glasgow, Scotland, contrasting the different between those who actually delivered mail and those who had office jobs. The office workers had higher BMIs, bigger waists and worse blood sugar and cholesterol issues than those who walked significantly more, and that's even after scientists adjusted for age, sex, family history and other factors known to impact health.

But the biggest differences were with mail carriers who walked at least 15,000 steps per day, which is the equivalent of about seven miles. They had normal waistlines, BMIs and metabolic profiles, meaning they showed no increased risk at all for heart disease. The results were published in the International Journal of Obesity.

The study is small and is a look at a small group of people, but it may be motivation enough to up your walking game to 15,000 steps, researchers say.

“It takes effort,” Dr. William Tigbe, lead author and public health researcher at the University of Warwick told the New York Times. People can get 15,000 steps a day by walking briskly for two hours a day, he says.

But you don't have to do it all at once, he points out. Try 30-minute walks in the morning and at lunch and short 10-minute breaks throughout the day.

“Our metabolism is not well-suited to sitting down all the time,” he concludes.

A better way

Senior couple walking Use your fitness tracker to help you reach your own, personal fitness goals. (Photo: Monkey Business Images/Shutterstock)

If you're trying to improve your health, and if your doctor gives you the go-ahead, there is a better way to use your fitness tracker to achieve your goal. First, wear your tracker for one week to set your own, personalized baseline for the number of steps you take each day. Then, according to the Mayo Clinic, you can try to increase that benchmark by around 1,000 daily steps every two weeks. So, for example, if you're currently walking 3,000 steps each day, you should aim for 4,000 steps daily and keep that up for two weeks before setting another goal.

Fitness trackers are excellent tools that can help you set and reach goals to improve your fitness. Just be sure that you're making those trackers work for you by choosing step goals that match your health and fitness needs.

Editor's note: This story was originally published in February 2017 and has been updated with new information.