Letting autoworkers sit while they reach into a car's interior could help prevent shoulder and back strain, but another solution might be to tilt the entire car so that workers can stand up.

That's the finding of two recent studies, which tested two ways to protect autoworkers from injury.

Sitting on a cantilevered chair reduced the stress on the workers' backs and shoulders for three common installation tasks. But a different strategy—tilting a car sideways on a carriage so that workers could access the interior while standing—reduced the stress for nine different tasks.

The car carriage appears to be a better overall option for preventing injuries, says William Marras, professor and Honda endowed chairman in the Department of Integrated Systems Engineering at Ohio State University.

Honda Motor Co. asked the OSU team to test the commercially available chair as well as the car carrier, both of which already are used in some of its plants and by other manufacturers around the country.

To use the chair, workers sit on a padded seat at the end of an L-shaped steel beam that is locked into a track above. The "L" slides back and forth as workers use their legs to pull the chair across the floor and into the car.

In only three situations—installing the roof console and insulation and tightening bolts in the center of the car did sitting in the chair reduce loads on the spine and shoulder stress.

The chair didn't help when workers had to reach the sides or back of the car, either.

In the car-carriage study, the researchers had 12 people install equipment in a car's interior, underbody, and engine room while standing. They measured stresses on the people's bodies when the car was tilted at different angles.

Of nine different installation tasks, seven became much less strenuous when the car was tilted on its side 45 degrees. The other two showed similar improvements when the car was tilted completely sideways at 90 degrees.