New Wearable Technology Helps Improve Mobility After Stroke
In a strong partnership between the John and Marcia Price College of Engineering and the College of Health, a new approach is showing promise for restoring mobility after stroke.
Although walking appears simple, it depends on complex neuromuscular coordination. After a stroke, when weakness affects one side of the body, the other side works harder to compensate, dramatically increasing the physical effort required for even basic movement. This can cause hemiparesis, a condition marked by impaired motor control, muscle weakness, and spasticity on one side of the body. Affecting roughly 80% of stroke survivors, hemiparesis contributes to reduced mobility, decreased independence, and significant declines in quality of life. It is also a leading cause of long-term disability in the United States. Individuals with hemiparesis often expend 60% more energy walking than people with a typical gait, leading to slower speeds, reduced endurance, greater pain, and an elevated risk of falls.
In a paper published in Nature Communications, the collaborative team demonstrated that a portable, lightweight hip exoskeleton can reduce the energy required to walk by nearly 20% in individuals with hemiparesis. Assistance levels are individualized for each patient, and an intelligent control system synchronizes with the walker’s natural rhythm—providing support precisely when the hip needs to lift or push off. Weighing just five and a half pounds, the device fits around the hips and attaches to the thighs. Battery-powered motors assist leg movement during each step, helping users achieve a more efficient gait pattern.
“One of the greatest challenges in stroke rehabilitation is improving long-term mobility and quality of life,” says Bo Foreman, PT, PhD, professor of physical therapy & athletic training in the College of Health and a collaborator on the study. “This work shows that assistive robotics can meaningfully address that challenge.”
The research was led by graduate student Kai Pruyn, with contributions from postdoctoral scholar Rosemarie Murray and research scientist Lukas Gabert. Their work highlights the interdisciplinary approach required to address complex rehabilitation needs.
Previous efforts to reduce the metabolic cost of walking after stroke often focused on powered ankle exoskeletons, targeting issues such as foot drop and impaired ankle propulsion. However, these devices have not successfully reduced walking effort.
“Patients with ankle weakness often compensate with their hips, which requires much more energy,” Pruyn explains. “Our goal was to design a fully portable hip exoskeleton capable of supporting these compensatory demands. Because the device sits closer to the body’s center of mass, it can be both extremely lightweight and highly effective.”
Other research groups have explored hip exoskeletons in healthy individuals, but this study is the first to show clear benefits for patients with hemiparesis. Using advanced motion-capture technology, the researchers analyzed gait patterns from seven participants walking on an instrumented treadmill both with and without the exoskeleton. Participants also wore metabolic monitoring equipment to measure energy expenditure.
The findings were significant: the exoskeleton reduced hip workload by nearly 30%, translating to an 18% decrease in the overall metabolic cost of walking.
“For someone with typical mobility, this improvement is comparable to taking off a 30-pound backpack,” Foreman says. “For a person living with hemiparesis, it can change the possibilities of daily life.”
Participants felt the difference immediately. “In the beginning, I couldn’t move my leg,” says Lidia Barrus, one participant. “But with the device, it’s much better now.” Her husband, Marcellus Barrus, added, “The more she used it, the better she was even when she wasn’t wearing it.”
Next steps for the research team focus on ensuring the device is functional and safe for home and community use. This includes refining the mechanics, enhancing the control system to support a broader range of daily activities, and partnering with prosthetics and orthotics experts to translate the prototype into a widely accessible clinical tool.
“Our goal is to expand what’s possible in stroke recovery,” says senior researcher Tommaso Lenzi. “A stroke should not define the limits of where a person can go or how they can live.”