Walking speed may predict survival in seniors

Walking is probably an activity you take for granted, but scientists say it could have something to say about the survival of older people.

A large study in the Journal of the American Medical Association finds that walking speed may be a good predictor of the life expectancy of senior citizens. Slowing down, it seems, may actually mean the end is nearer.

"This gives us another way to monitor our health and explore ways to age as well as possible," said Dr. Stephanie Studenski, researcher at the University of Pittsburgh and lead study author.

This does not mean, however, that you should try to change your walking speed, she said. The point of the research is that many systems in your body - cardiovascular, musculoskeletal, nervous and others - contribute to the way that you walk, and the health of those systems may be reflected in your natural pace.

Researchers analyzed data from nine different studies, collectively looking at nearly 35,000 adults aged 65 and older. Participants lived in the community - not in nursing homes or other institutions - at the time of the research and included members of both sexes and various ethnic groups. The various studies had looked at how fast participants walked over a fixed distance at a usual pace, beginning with them standing still.

They found that the higher the walking speed, the longer a person is expected to live. This appears to be as good an indicator of longevity as age, sex, chronic conditions, smoking history, blood pressure, body mass index, and hospitalization history in the last year.

For example, researchers found that for a 70-year-old man, the difference between walking 3 mi/hr and 3.5 mi/hr was four years of life on average; for a woman, it's six to seven years. A 70-year-old man who walks at 2.5 mi/hr would expected to live an average of eight years longer than if he walks at 1 mi/hr; for a woman, that difference is about 10 years.

"If you have a natural walking speed that’s pretty brisk, that’s a good sign of how you’re doing," Studenski said.

The study found that walking speed was the strongest predictor of lifespan in older people who were independent or only had trouble with non-instrumental functions such as shopping, housework and cooking. For those who cannot do basic activities such as feeding and dressing themselves on their own, walking speed may be less relevant.

"If you’re already having a lot of trouble, gait speed doesn’t help as much," she said.

Of course, this is all based on probabilities, and it's by no means a death sentence. There are some elderly people who walk slowly and will live many more years, just as there are certain people who have high blood cholesterol and never have a heart attack.

One important potential application of this research is helping older people decide whether certain preventive tests, such as prostate cancer screenings, are worth their while. If their walking speed suggests that they are expected to live  10 more years at age 70, that might be an important factor in making decisions about such tests.

Walking speed might one day become as relevant as blood pressure as an indicator of overall health, she said. But, it will take time to see how useful it is to doctors and patients.