Behavioral researchers from the Oregon Research Institute in the United States investigated the health effects of cobblestones after observing people exercising and walking back and forth over traditional stone paths in China.

"We noticed in several cities we visited that people were walking on cobblestone paths, and people were standing on them, and sometimes dancing on them, doing weight-shifting," said John Fisher, who led the study. "We thought if we could scientifically measure it, we could see if there were health benefits."

The results surprised Fisher and his fellow researchers, who expected to see some general improvement in health, but also saw blood pressure drop measurably among the volunteers during the 16-week study. 

"It's very provocative," said Dr. David Ellison, the chief hypertension expert at Oregon Health & Science University in Portland. "If they had done it over two years and lost 10 pounds (4.5 kg) I might be less surprised, but to do it that quickly — it's certainly dramatic."

The researchers simulated the rounded, river rock cobblestones with a specially designed mat that was 2 meters long and a half a meter wide. Some of the test subjects walked in their bare feet, others wore socks.

They were compared with a control group who simply walked for an hour, three times per week. The results were published recently in the Journal of the American Geriatrics Society.

Nearly all the 108 volunteers in the study said they felt better after the exercise. But only the half who walked the cobblestones showed significant improvement in balance, measures of mobility and blood pressure, Fisher said.

He said the cobblestone walking paths are common in China, where traditional medicine teached that the uneven surface of the stones stimulate "acupoints" on the soles of the feet. The theory is much like acupuncture, suggesting that distant and unrelated areas of the body are linked together at certain points and can be stimulated to improve physical and mental health.

Fay Horak, an Oregon Health & Science University neurophysiologist who specializes in balance, said the study was evidence that finding ways to maintain mobility and balance could delay and even prevent the effects of aging. 

"I'm not surprised that working on balance improved balance," Horak said. "There's a lot of evidence that shows no matter who you are, it improves if you challenge it."