How You Walk May Be a 'Gaitway' to Your Personality, Biology

October 28, 1999

SEARCH THE GAZETTE

HARVARD GAZETTE ARCHIVES

By William J. Cromie
Gazette Staff

Jeffrey Hausdorff with a force plate which measures variations in walking that can reveal the risk of falling in the elderly and the specificity and severity of some nervous system disorders. Photo by Jon Chase.

Scientists are bringing a different meaning to the old saying: you can tell a lot about people by the way they walk.

It’s not just that they’re tired, hurting, or drunk. New ways of measuring gait reveal whether an elderly person is more or less likely to fall, when a child’s muscle and nervous systems are fully matured, and the severity of maladies such as Parkinson’s and Huntington’s diseases. Variations in ambulation have even been found to be indicators of heart failure and depression.

"Over hundreds or thousands of strides, we see patterns of fluctuations that give us an inexpensive way to monitor many functions of life and to detect diseases," says Jeffrey Hausdorff, assistant professor of medicine at Harvard Medical School. "For example, older people at high risk of falling have about five times more variations in their gait than those not likely to fall. In Huntington’s disease, we see a breakdown in almost every aspect of the general walking pattern."

Working at Beth Israel Deaconess Medical Center, a Harvard-affiliated teaching hospital in Boston, Hausdorff and his colleagues designed, built, and now use equipment to determine exactly how much they can learn about people from analyzing the way they walk.

To record subtle stride-for-stride changes, these researchers put a force-sensitive plate, no thicker than an arch support, in one shoe. Then a small recorder, no larger than a pack of cigarettes, is connected to the plate’s switch and strapped to the ankle. This simple, inexpensive rig makes a detailed record of the timing and stability of a person’s gait, a record that can be played on a computer. The resulting graph, which looks like an electrocardiogram, reveals difficult-to- detect variations in stride, wobbliness, and balance.

When a person is healthy, the gaitogram shows a hidden, or involuntary, body rhythm. When muscles, nerves, brain, and heart work in normal, healthy ways, experts can predict the "notes" that came before and those that will come after the measurements are made. But when the rhythm becomes dissonant, the walk "sounds" a warning that all is not well.

Exercise Reduces Risk of Falls
Now that it’s possible to obtain this kind of information, Hausdorff and his colleagues are looking at what can be done with it. They are completing a study showing that exercise may improve gait stability and reduce the risk of falls and the resultant injuries, one of the most common medical problems among the elderly.

In the study, seniors ranging from age 70 to more than 90 years lifted weights and took balance training. Their walking records were then compared to elders who did not work out.

"Initial results suggest that, with the right exercise, you can decrease wobbliness and reduce the risk of falling," Hausdorff notes. "Such exercise probably needs to be robust and involve different types of progressive resistance training, that is, working against increasing resistance. Simply standing and stretching won’t do it."

Hausdorff worked with Miriam Nelson and Maria Fiatarone Singh of Tufts University in Boston on this project, and they continue to do follow-up research. Their goal is to determine what kind of exercise works best for different groups of oldsters.

Falling has multiple causes, so no one expects a one-solution-fits-all outcome. Other researchers have found evidence that tai chi reduces tumbles.

"Falling often gives rise to fear of falling," Hausdorff points out. "That leads to a vicious cycle of less activity, weakened muscles, and an increased likelihood of falling. It’s a chain that needs to be broken by exercise and other means."

Testing Children
On the other end of the age range, Hausdorff found some surprises. After age 3, children start to lose their tottering walk, and by age 7 they seem to walk much like adults. But gait recordings tell a different story.

"Small stride-to-stride variations in gait indicate marked differences between 7- to 8-year-olds and 11- to 14-year-olds," explains Hausdorff. "Young people may not exhibit a fully mature walking pattern until 18 years or older. Part of the explanation might be that the nervous system isn’t completely developed until then."

Hausdorff sees the possibility of using gait patterns to help determine if a youngster’s nervous system is on the right track to healthy maturation. He sees it as an indicator that might be used along with height, weight, and other markers.

"There may be other problems reflected in gait variations," Hausdorff speculates. "It’s worth looking into. Changes in walking might be used to assess the results of different drug or other treatments given to children. It’s a quick, easy test that can be done anywhere."

Gait Breakdowns
As an individual ages, he or she develops more variations in gait, a sign that muscles weaken and nerves aren’t as responsive. These normal changes, however, are different from changes that occur when someone has a brain or nervous system disorder such as Parkinson’s, Huntington’s, or amyotropic lateral sclerosis (Lou Gehrig’s disease). Like fluctuations tied to maturation, these changes may, at first, be too subtle to determine visually.

"Patterns of walking related to underlying workings of the nervous system apparently become altered in disease-specific ways," Hausdorff explains. "Parkinson’s shows a different pattern from Huntington’s. And the severity of the breakdown is related to that of the illness."

This relationship has led Hausdorff and Ary Goldberger, an associate professor of medicine at Harvard Medical School, to consider the possibility of early detection of such diseases from changes in the way people walk.

"Based on research so far, we’re optimistic that monitoring gait could help diagnose a variety of nervous system disorders, particularly when used in combination with other tests," Goldberger says. "It provides numerical data that is more accurate than visual or subjective impressions. And it might detect changes that tell us whether or not a treatment is working or making things worse."

In the early 1990s, Goldberger and his colleagues discovered that small differences in heart beats can be used to both detect the rate of aging and to warn of impending heart disease. All healthy people experience these complex rhythmic changes, and if the rhythm starts to change in certain ways, it signals trouble.

When Hausdorff checked the gaits of healthy people, he was startled to find them characterized by the same type of rhythmic patterns. "I could not have been more surprised," he admits.

These findings led to a study of how heart failure might affect a person’s strides. Sure enough, Hausdorff and Goldberger found that people with heart failure wobble more when they walk.

The severity of heart failure is usually measured by having a patient walk as fast as he or she can for six minutes. The shorter the distance covered, the greater the degree of disease.

"We found gait variability measurements to be better at distinguishing the degree of heart failure than the six-minute walk," Hausdorff notes. "We need to follow this up to see how useful it might be as a way to make more accurate diagnoses of heart failure and responses to treatment."

Goldberger sees other applications for their basic findings about hidden body rhythms. "Certain patterns appear to be a generic characteristic that shows up in the working of the nervous system, heart, and even the brain," he says. "We have recently initiated studies to measure how depression and other psychological changes may influence the way a person walks."