‘Like dancing with a really bad partner’: Exoskeletons can confuse the brain, researchers say

Columbus, OH — The physical benefits that exoskeletons provide to the musculoskeletal system may be negated by the “mental strain” that results when workers wearing the devices perform tasks that require them to think about their actions, results of a recent study conducted by researchers from Ohio State and Texas A&M universities indicate.

The researchers asked six men and six women to repeatedly lift a medicine ball during two 30-minute sessions. In one session, the participants used a passive exoskeleton – designed to reduce lower back pain – attached to their legs and chests. During the other session, the device wasn’t used.

Infrared sensors were used to track the participants’ brain activity and measure the force on their lower back while the researchers recorded the number of times each participant lifted the ball.

Then, in separate sessions, the participants were asked to subtract 13 from random numbers ranging from 500 to 1,000 each time they lifted the ball.

The researchers found that “when the participants were simply lifting and lowering the ball, the exoskeleton slightly reduced the load on the participants’ lower backs,” a report published by OSU’s Ohio State News states. “But when the participants had to do math in their heads while lifting and lowering the ball, those benefits disappeared.”

Senior study author William Marras, professor of integrated systems engineering and director of the OSU Spine Research Institute, notes in the report that psychological stress or instructions that employees must follow may have the same effect in the workplace.

“It’s almost like dancing with a really bad partner,” Marras said. “When we looked at what was happening in the brain, there was more competition for those resources in the brain. The person was doing that mental math, but the brain was also trying to figure out how to help the body interact with the exoskeleton, and that confused the way the brain recruited the muscles to perform the task.”

Marras told Ohio State News: “All exoskeletons aren’t bad, but people are messy, and everyone is different. You’ve got to use exoskeletons with some intelligence and some understanding of what the job entails.”

He and the other researchers say that “systematic neuroergonomic investigations that compare multiple exoskeleton devices and/or designs are needed that can set the foundation for evaluating different device features on their cognitive and motor processing requirements during various manual handling tasks.”

The study was published online June 11 in the journal Applied Ergonomics.