Something in the Way We Move
Elizabeth “Betsy” Coker’s research is a perfect pas de deux between art and science.
Why art? Because, as a longtime professional dancer and now an assistant arts professor in the Department of Dance at Tisch, Coker understands instinctively how the body moves to music.
Why science? Because, building on her dance background, Coker has made movement science her life’s work. “As a creative practitioner, I’ve spent my entire life thinking about moving,” she says. “It is the thing that has occupied all of my thought and imagination since I was a kid.”
Indeed, Coker was only 3 when she began training as a classical ballet dancer, and by 16 she was dancing professionally with the Washington Ballet. Coker delayed the start of college to perform, but she ultimately earned her bachelor’s degree in psychology from Columbia University, which she followed up with master’s and doctorate degrees in motor science.
It was during her master’s studies at Columbia that Coker sat in on a graduate seminar that changed her life. “A group of people were arguing about brains and bodies and movement,” she recalls. “They were not dancers, but I thought, ‘This feels so much like what I do and what I think about.’ It blew my mind.”
That was the moment when she realized that the “body knowledge” she’d acquired from years of dancing could be applied to movement research. “Even the phrase ‘mind-body connection’—we assume that the mind and body are separate,” she says. But when a person dances, “every corner of the body is illuminated in this effortful, intellectual, cognitive, creative, imaginative way.”
In two intriguing studies currently underway, Coker is looking at populations on different ends of the movement spectrum, from “people who have a lot of motor experience, specifically dancers, to people who may have various disorders or differences in the way they move.” For these studies, she developed a new iPhone app that collects movement metrics through its internal sensor. It allows Coker and her primary collaborator—Anat Lubetzky, an associate professor in the Department of Physical Therapy at NYU Steinhardt—to research what they call “accessible movement measurement,” in other words, quantifying, outside the lab, how humans move and balance.
The first study, which has two parts, examines how balance changes as we age. Looking at two distinct populations—people under 40 and over 60—Coker assesses balance by asking each participant to attach a smartphone running her app to their midsection and complete 30 minutes of exercises under Zoom guidance. The exercises—asking subjects to stand with feet touching, stand as if on a tightrope with one foot in front of the other, or stand on just one foot, with eyes either open or closed—might sound easy, but they are not. (Just try standing on one foot with your eyes closed.)
And Coker and Lubetzky added a final cognitive variation: asking subjects to cycle through the stances while counting backward. “We know that people have more difficulty balancing with their eyes closed, no matter what the age, although the older you get, the more difficult it becomes,” Coker says. “The counting exercise helps us understand what the person is prioritizing—is it their balance over a cognitive task?” The study is not yet complete, but so far it appears that if older people are asked to stand on one foot with their eyes closed and then count backward, they will usually prioritize the motor skill—meaning they will stop counting to maintain their balance—while younger individuals are more likely to keep counting, even though they may wobble more.
A critical component of the study is to determine whether this app can be used without professional guidance over time by people of various ages at home. If so, then Coker’s app could be a game changer enabling a much, much wider population—those who cannot make it into a pricey, staffed lab because, for example, their mobility is limited by Parkinson’s or multiple sclerosis—to test themselves at home using the app. “It’s like a thermometer,” she says. “Everybody has a thermometer. By taking our own temperatures, we can get a sense of what is going on inside our bodies.” So ideally clinicians could extrapolate from a patient’s iPhone data to find out if something is going wrong with their balance.
“We know that impaired balance is implicated in a variety of neurological disorders—Parkinson’s, multiple sclerosis, Huntington’s,” Coker says. But so far, scientists have struggled to study people before they are diagnosed. With this app, individuals who take self-readings might notice their balance changing over time. “That early-warning-sign component is huge,” she says.
Another potential use: fall prevention. According to the CDC, each year 3 million older Americans are treated in ERs because of falls, with more than 800,000 being hospitalized, most often because of a head injury or hip fracture. And more than 95 percent of hip fractures are caused by falls. “Right now, falling in older people is a huge problem,” Coker says. “But studies are focusing on predicting future falls based on past falls. The million-dollar question is: How do you detect or prevent the first fall? How do you know if someone is at risk?” This app could help.
The second half of this study will involve a shorter set of similar exercises done by unmonitored users (people not guided by Zoom instruction). The ultimate goal: to build a database of balance measures across the life spans of a large population. Currently, Coker says, “I can’t look at a table and say, ‘I’m a 40-year-old female; what should my measure look like?’ For a reference data bank, you’d need tens of thousands of people.” And the iPhone app could help researchers get there.
But that longitudinal, diagnosis-prevention study is only half of the puzzle, she says. The mirror of that is her second study, which uses the app to measure rehabilitation—specifically, from something extremely common in dancers called chronic ankle instability.
Often, even after an injury appears to be healed, a dancer will have balance issues. Coker explains it this way: “Ligaments [in ankles] often interact with these sensors called proprioceptors, which give us information about where our bodies are in space. That is really important for balance. With ankle injuries, you often see disruptions to that proprioceptive ability. That is why an ankle injury can be resolved, the physical therapy finished, and the ankle muscles strong, but there are still these unaddressed disruptions to the proprioceptive faculties.” The result? A case of the wobbles.
In this study, Coker and Lubetzky are using the iPhone app to measure balance in three sets of dancers: those with no history of ankle injury, those who’ve had one ankle injury, and those who’ve had both ankles affected. The dancers run through the usual battery of “eyes open, eyes closed, one foot down, one foot up” exercises but face two extra challenges. First, the researchers “perturb their vision” by having them wear virtual reality goggles that show them a star scape in which the stars are either unmoving or moving ever so slightly. “That visual perturbation makes it much harder to balance,” Coker says. “If everything in your visual surrounding starts moving, your brain’s first thought is that you’re falling.” In the second challenge, the dancers wear headphones and hear either no sounds or “moving” sounds; the goal is to figure out whether audio perturbation affects standing balance.
Though not yet complete, the intent is that the study’s results could have important real-world applications. “A better understanding of how the brain changes in response to peripheral orthopedic injury could unlock new therapeutic approaches to injury rehabilitation,” Coker says. “For example, how can we address the cortical injury response that may linger after the peripheral injury appears resolved? Some researchers are using motor imagery toward this aim, and we’d like to more thoroughly understand the mechanisms of action of these imagination-based therapies.” (That, she hopes, will be the focus of an upcoming study.)
“There are some exciting—perhaps more distant—implications for our understanding of pain, fear, and reinjury anxiety as well, clinically bridging the gap between an athlete who’s physically ready to return to play but may still face some psychological and functional barriers.
“There is so much we don’t know about movement disorders, about aging and movement, about movement rehabilitation, about where movement resides in the brain,” Coker says, summing up her work. “I find that really motivating.”
Photos from top: courtesy of Betsy Coker; Joe Carrotta