Simone Gill (left) and her doctoral student Danny Shin are gathering data on the walking patterns of people following weight loss. Photo by Michael D. Spencer

In 2017, Danny Shin, an occupational therapist in inpatient care at a hospital, was working with one of his patients, a man with a movement disorder. The patient was doing particularly well, Shin (’22) recalls. “He never fell with me, ever, in the hospital.” And yet, as soon as he returned home, the man took a tumble.

What happened? Shin wondered. “Physically, he was fine. He was safe to be home.” Had the patient felt comfortable in a hospital setting, but lost that confidence when his environment changed? Or had he instead become overly confident and pushed past his limits? There was also a chance, Shin reasoned, that self-confidence wasn’t a part of the equation at all.

Shin has been studying that relationship between self-confidence and walking at Sargent where he’s pursuing a PhD in rehabilitation sciences. He’s conducting that research in the lab of Simone V. Gill, an associate professor of occupational therapy. Gill has spent a decade at BU studying the ways obesity affects walking patterns and contributes to fall risk, often working with people undergoing bariatric surgery. “One other thing, though, that goes into falling isn’t just physically what you can do,” Gill says. “It’s how confident you feel about moving around. After individuals lose massive weight, it’s like getting used to an entirely new body.” The two have designed a new study that examines both the physical and emotional changes resulting from such massive weight loss.

People who undergo bariatric surgery can lose up to 35 percent of their body weight in a single year. “I was very curious about what happens when there’s a change in your body that’s so sudden.”
—Simone Gill

Research has shown that people with obesity move differently, with a wider gait, than people with average body mass indices when walking on flat ground and navigating environmental obstacles. They tend to walk more slowly and take shorter, choppier steps; they also prioritize spending time on both legs, rather than balancing on one at a time. “It sounds like it should make them more stable,” says Gill, “but it actually predisposes them to more falls.”

Even after bariatric surgery, a patient’s movements don’t completely return to baseline. “There’s an argument for rehab because their walking patterns haven’t matched those of people with average body mass who never were living with obesity,” she says.

Gill’s interest in this research is, in part, personal. In 2012, she weighed 225 pounds; today she weighs about 130. Although she did not have bariatric surgery, “I was interested in differences in how I moved after losing about 90 pounds.” People who undergo bariatric surgery can lose up to 35 percent of their body weight in a single year. “I was very curious about what happens when there’s a change in your body that’s so sudden.”

For their study, Shin and Gill, who also directs Sargent’s Motor Development Lab, asked 12 adults prior to bariatric surgery to navigate five courses, which ranged from flat ground to high obstacles. Participants returned 4, 8, and 12 months after the surgery to repeat the course. A gait carpet tracked the position and timing of their footsteps, capturing digital representations of their footfalls as they walked.

At each visit, participants were also asked to complete two tests to measure self-efficacy: the belief that you can successfully complete a particular task. The first test, known as the falls efficacy scale, describes how confident a person feels that they can complete a functional, day-to-day activity—such as cooking dinner or taking a shower—without falling. The second test, called the modified gait efficacy scale, is newer and less commonly used. It tests for confidence in challenging circumstances, such as walking safely across a grass lawn or stepping up on and down from a curb.

So far, Shin is in the preliminary stages of data analysis. Early results show definite changes in walking patterns: after surgery, participants walk faster and with a narrower gait. Self-efficacy also shows a general improvement between the zero- and four-month mark. Examining these factors in concert is important, Shin says, because “if someone has low self-efficacy, even if they are physically capable of doing something, a lot of people still choose not to do it.” Walking is one of the least expensive and most commonly prescribed methods to combat obesity, yet patients often avoid it. This study could add another layer of data to help explain why.

Shin presented these findings at the annual Gait and Clinical Movement Analysis Society conference in March 2019. For Gill, that is an important part of the student experience. “It’s an opportunity to learn how to disseminate his work to other scientists,” she says. Another focus for Gill is to create a space where Shin and her other doctoral students can lead in the lab. “They have to learn how to be scientists, but they also have to learn how to mentor others.”

With that in mind, Shin is working with several students involved in BU’s Undergraduate Research Opportunities Program. “We show them what data collection looks like, what kind of protocols we follow,” says Shin. “They get a behind-the-scenes look at what research is.”

Shin will continue to process the data he and Gill have collected to learn which measures show improvement—or don’t—across the 8- and 12-month check-ins. The next step may be intervention—physical therapy, for instance, or home-based activities that can be monitored by practitioners through wearable devices—in order to decrease the risk of falls. Shin also speculates that their research into self-efficacy may highlight the importance of an existing practice: home assessments. Many occupational therapists visit their patients’ homes during treatment, to ensure that their work in the clinic mirrors real-life obstacles. “We want to really emphasize to people that they’ll be able to translate their walking abilities from the clinic to their environment,” he says.

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