A participant in a study at The Ohio State University performs a simulated wheelchair turning task. (Photo courtesy of Eric Weston, The Ohio State University)

A participant in a study at The Ohio State University performs a simulated wheelchair turning task. (Photo courtesy of Eric Weston, The Ohio State University)

Hospital workers and others who push patients in wheelchairs may be hurting their backs without knowing it, researchers suggest.

Researchers from The Ohio State University Spine Research Institute, in a study that appeared recently in the journal Ergonomics, measured the forces on the spine caused by pushing a wheelchair, and discovered that people aren’t good at judging when they’re exerting forces strong enough to hurt their back.

When asked to push a simulated wheelchair against increasing resistance, study participants typically exceeded the recommended limits to avoid back injury by nearly 20% before they decided to quit, explains a media release from Ohio State University.

“Today, patient handling is one of the most dangerous jobs for your back. It’s more dangerous than working in construction, more dangerous than mining or any of the other jobs we typically think of as difficult,” says William Marras, director of the institute and Honda Chair Professor of Integrated Systems Engineering at Ohio State, citing data from the Bureau of Labor Statistics, in the release.

In the study, 62 volunteers—31 men and 31 women, with an average age of around 25 years—pushed against a rig attached to an overhead braking system with adjustable resistance. The rig simulated the average height and placement of wheelchair handles. While the resistance started low, it increased until the volunteers felt like they couldn’t move the rig any farther. All the while, researchers measured the forces on the discs of their spine. The heaviest loads, though few participants reached them, corresponded to pushing patients weighing up to 485 pounds (220 kilograms).

The people in the study tended to keep pushing an average of 17% to 18% past the point where they should have stopped, based on the forces on their spine, the release explains.

While pushing against the simulated wheelchair, male volunteers pushed past this limit about 34% of the time.

In addition, the researchers observed that turning a wheelchair is harder on the back than pushing in a straight line. Turning the wheelchair increased the spinal forces by roughly 40%, because the volunteers had to stabilize their back using their core muscles while they pushed with one hand and pulled with the other.

Based on the study’s results, the research team suggests wheelchair design changes that may help make wheelchairs easier to push. These could include making handle heights adjustable or able to rotate 90 degrees to be more like a shopping cart.

“We would also suggest building motor-assisted wheelchairs that could aid the person pushing when the pushing forces get too high,” states doctoral student Eric Weston, who performed the study for his master’s thesis, in the release.

“When you look at the part of the back that we’re concerned about—the disc—it doesn’t have a lot of nerve endings, so you couldn’t possibly know whether you’re doing damage or not. That’s why we wanted to do something quantitative,” Marras concludes.

[Source(s): Ohio State University, Science Daily]