LONDON — Attention all shoppers: taking the stairs protects your heart.

That's the message researchers tried at a suburban shopping mall by putting up colorful signs along the steps of a staircase, and it worked. Over six weeks, use of the stairway next to an escalator more than doubled.

Normally, about 4 percent of people at the mall take the stairs but after adding the signs, that went up to nearly 10 percent. The findings were recently published in the American Journal of Health Promotion.

"A certain segment of the population clearly responds to these messages," said Frank Eves, one of the study's authors, and a senior lecturer in applied psychology at the University of Birmingham.

Eves and colleagues counted the number of people at a mall who climbed the 15 steps before the signs went up and after they were posted. They counted more than 82,000 shoppers at the mall in Coventry in western England,

"If we can persuade more people to take the stairs, then we might really have something in the war against obesity," he said.

With fewer daily opportunities for physical activity in modern society, public health officials are increasingly focusing on stairs at schools, workplaces, and even the mall. Past studies have shown that the decision to take stairs can be manipulated with a few signs.

Eves and his co-author, Oliver Webb of Loughborough University, also found more people walked down the stairs at the mall, even though they couldn't see the signs. The 25 percent increase suggested people had remembered the messages from going upstairs earlier, and consciously decided to take the stairs on the way down, Eves said.

Experts emphasize that just climbing one flight of stairs at a shopping mall is not going to improve your health. But they hope the signs may inspire some people to regularly forgo escalators in the future.

"Unless you're climbing six or seven flights of stairs a day, it's probably not a substitute for daily exercise, but every little bit helps," said Tim Armstrong, a physical activity expert at the WHO.