July 13, 2016
By Greg Peters
What do multiple sclerosis patients involved in a research study at the Human Performance Laboratory at the University of Kansas Medical Center have in common with the video game Guitar Hero, an ad for Barbie dolls, or the groundbreaking movie, "Avatar"?
The answer, it turns out, is quite a bit.
While it's a long way from Hollywood to Kansas City, Kansas, where the Human Performance Laboratory is housed inside the Landon Center on Aging on the KU Medical Center campus, the technological leap tying them together is much closer. Lab director Jessie Huisinga, Ph.D., and her fellow investigators are surrounded by full motion-capture systems similar to those used by filmmakers, animation studios and video game creators. But in this case, the technology is being used for health care research rather than the next movie blockbuster.
"There is definitely a coolness factor when you're using full motion-capture," Huisinga said. "But you forget about it because you work with it so much. I have to remind myself and my graduate students that this stuff is really cool."
The Human Performance Lab is a place where health care research and biomechanical engineering collide for the sake of patient care. Researchers use both wearable and non-wearable high-tech gadgets to accurately record movement and balance issues for a variety of test populations in an effort to unravel the mysteries of diseases such as multiple sclerosis and Parkinson's.
Coolest of the cool
Perhaps the coolest of the cool stuff is the motion capture system, which features eight high-speed digital cameras suspended at strategic locations along lighting rails inside the 2,500 square-foot lab space. The cameras are built by MotionAnalysis Corp. from Santa Rosa, California, whose products are used for everything from animation to movement analysis.
"Because I'm not trying to make an animated movie or a video game, I can use a less-detailed model that tells me what I want to know about how a patient's legs are moving or how their trunk is moving," said Huisinga, who has a doctorate in biomechanical engineering.
Huisinga says there are engineering rules regarding how many cameras are needed to define the coordinates of a marker when capturing three-dimensional movement. Basically, in the Human Performance Lab, cameras are positioned in such a way so each marker is covered by at least two cameras at all times during testing.
For most of their studies, Huisinga and her team use 33 reflective markers placed at specific spots on the lower portion of the research subject's body. The cameras capture images produced when infrared light generated by the camera bounces off the reflective markers on the subject. What results is a three-dimensional model based on the data from the capture system.
Data from the cameras flows into special motion-capture software and is used to generate an animated model of the subject's movement. It's the exact same process animators and video game producers use to conjure up dragons and demons in fine detail, only in this case, in much lower definition since fewer cameras and sensors are needed for research.
"What's nice about the cameras is the user defines how the technology is going to be used," Huisinga said. "There's a trade-off with resolution. If you want to have 100 markers for more resolution, you need to have more cameras, so that all the markers can be tracked in real time."
Beyond motion-capture video
The list of high-tech devices used in the lab doesn't stop with motion-capture cameras. Wireless electromyography sensors are worn on the body to detect when specific muscles are firing. Wireless inertial sensors are wearables that are worn on the wrists, ankles, waist and sternum that use a gyroscope and accelerometer to record a variety of body movements. The lab is also equipped with force platforms embedded in the floor. These high-tech scales give researchers a three-dimensional footprint of the test subject.
These devices can be used by themselves during a test or in concert with other instruments like the motion-capture cameras, depending on what investigators are studying.
The Human Performance Lab, which is dedicated to the study of motor function through interdisciplinary research and education, is engaged in a variety of studies, many of which involve chronic progressive conditions such as multiple sclerosis and muscular dystrophy. The largest study currently going on is sponsored by the National Multiple Sclerosis Society and is exploring walking and balance issues in people with MS.
Another project looks at the relationship of gait and balance metrics using the motion-capture system and changes in the brain and spinal cord measured with MRIs to determine if multiple sclerosis patients will have an imbalance dysfunction and when it might happen.
Research tests done in the lab vary based on the specific condition that is being studied. Generally, testing includes an over-ground walking test where the subject moves back and forth through the video capture field. During these tests, data is often taken from the cameras, wireless sensors and the force plates. A treadmill can also be moved into the capture field for testing.
Another commonly used test is to have a subject stand on the force plate, so researchers can manipulate the sensory input the person receives. That could be activities such as standing quietly with their eyes closed, or doing a counting task.
Huisinga said patients have been impressed with the technology as well.
I can't tell you how many people with MS I've tested and they say, 'we're so thankful you're doing this research,'" she said. "It's humbling to be thanked by a person who says your research is having an impact on the problems they're having in their day-to-day life."