Exoskeletons Designed To Help Reduce Back Pain Can Cause Mental Strain

Researchers from Ohio State University have conducted a new study looking at exoskeletons designed to help relieve back pain. Research is being conducted on exoskeletons by researchers worldwide with the idea that someday they could help people with limited or no mobility to return to regular activities. However, the new study has found that wearable devices used by workers on assembly lines or in warehouses to alleviate stress on the lower back could compete with available mental resources during work.The exoskeletons could lead to brain fatigue, canceling out the physical benefits of wearing the exoskeleton. The recently published study found that when people wore exoskeletons while performing tasks requiring them to think about their actions, the brain worked overtime, and the body competed with the exoskeleton rather than working in harmony with it. The study found that exoskeletons may place enough burden on the brain to negate any potential benefits for the body. Senior study author William Marras likened it to dancing with a really bad partner.

Marras says the exoskeleton tries to anticipate how the wearer will move, but if its anticipation doesn't go well, the user fights with the exoskeleton. Fighting with the exoskeleton leads to a change in the brain that changes muscle recruitment and could lead to higher forces on the lower back resulting in possible pain and injury. In the study, researchers asked 12 people to repeatedly lift a medicine ball in two 30-minute sessions. In one of the sessions, the user wore an exoskeleton, and for the other, they did not.

The exoskeleton was attached to the user's chest and legs and was designed to control posture and motion during lifting to protect the lower back and reduce the chances of an injury. Infrared sensors were used to evaluate the participants' brain activity and measure the force on each user's lower back during the session. In another session, the user was asked to lift the medicine ball for 30 minutes, with one session wearing the exoskeleton but having an added mental task.

In that session, the participant had to do math in their head while lifting and lowering the ball. Researchers found that when a mental task was added, any benefit to wearing the exoskeleton disappeared. Marras admits that exoskeleton users on an assembly line may not have to do math in their head, but other mental strain such as stress or instructions they have to follow could have the same negating effect.