TUESDAY, Jan. 4 (HealthDay News) -- Simply measuring how fast older people walk may provide a glimpse into how many years they have left.

In fact, a new analysis found that a formula that includes gait predicted older people's future life span about as well as taking into account such health conditions as blood pressure and heart disease.

Walking speed may not be a perfect window into a person's future, but the findings show that there's evidence to support the common assumption that older people fail to walk easily when their health is poor, said study author Dr. Stephanie Anne Studenski, a geriatrics specialist at the University of Pittsburgh.

"Somehow, the capacity to move is a powerful reflection of health, vitality and life expectancy in older adults," Studenski said.

It does appear obvious, she said, that the way people move -- or don't move -- is directly related to their health.

"We have always implicitly used things like the capacity to move and the vigor of movement to get an impression of how people are doing as they age," she said. "'Uncle Joe still has a spring in his step.' 'I'm worried about Grandma; she looks like she's slowing down.'"

But the question is this: Can research prove those assumptions?

In the new report, published in the Jan. 5 issue of the Journal of the American Medical Association, Studenski and her colleagues combined and analyzed the results of nine studies, involving 34,485 people aged 65 years and older. The studies, dated from 1986 to 2000, measured how fast people walked, among other things, and then followed them for as long as 21 years to see what happened to them.

The researchers found that walking speed was directly related to survival: People who walked faster tended to live longer, and the opposite was also true. Predictions based on gender, sex and walking speed were as accurate as those that largely relied on whether someone had medical conditions, high blood pressure and problems such as obesity.

So are slow walkers doomed to an early grave? Absolutely not, Studenski said. "There is clearly a group of people who walk slowly and live a long time," she said. "It's not a death sentence."

On the other hand, there's also no evidence that you'll live longer if you boost your walking speed, she said.

Even so, a slow gait can be a warning sign. A walking speed of 2.5 miles an hour is very good, she said, whereas 1.6 miles an hour or less could be an indication of medical problems.

Long walks aren't necessary: It's possible to gauge someone's gait by timing them as they walk just a few feet, she added.

Dr. Matteo Cesari, a geriatric specialist in Rome, pointed out in a commentary in the journal that the report found that the ability of walking speed to predict life span is only "statistically fair." Still, Cesari said, the findings are important because they give doctors another measuring tool.

"For sure, physicians get a pretty good sense of their patients by just looking at them, but this evaluation is still subjective and not based on a standardized evaluation," Cesari said. "In fact, the way one physician judges the overall health status of his or her patients may not the same as another one. By testing gait speed using the standards promoted by this study, every physician will be able to reach the same conclusion about the overall health status of a patient."

More information

The U.S. National Institutes of Health has more on healthy aging.