By Lanesha Reagan
Loud beeps echo down the hall in the Women’s building, signaling the start of a machine the size of a small car that looks like a mechanical spider. I sit in a seat above its many legs, and my heart drops as it goes silent and lifts me higher. A moment later the machine — which scientists call the Six Degree-of-Freedom (6-DOF) motion platform — begins to vibrate and move up and down, from side to side and forward and back.
Luckily, I am strapped in with a seatbelt. The constant vibration doesn’t shake me right out of my seat. However, I do get a tingling in my back. That’s a clue to the purpose of this facility in Jay Kim’s lab. He’s busy trying to solve a major occupational health issue that has shaken the trucking, mining, construction and agriculture industries for decades.
About 75 percent of workers who operate heavy machinery in these fields suffer from muscle and joint pain. In 2016, Kim and collaborators at the University of Washington and Northeastern University reported that low-back pain was the most prevalent of all the possible musculoskeletal ailments experienced by these drivers.
Kim is an assistant professor of Environmental and Occupational Health in the College of Public Health and Human Sciences at Oregon State University. His study is funded by the Alpha Foundation and aims to evaluate the effects of whole-body vibration (WBV) exposure on low-back pain, biomechanical loading and physiological stresses in the musculoskeletal system.
“The study itself originated from a lot of field based epidemiological studies,” says Kim. “They have shown significant levels of exposure to whole-body vibration from moving vehicles, including semi trucks, heavy vehicles, vehicles in construction, mining and agriculture, as well as metro buses. Those exposures have been associated with various adverse health outcomes, including musculoskeletal disorders, especially in the low-back and neck regions.”
Back Injuries Are Prevalent
Studying the impacts of such exposure is only one aspect of Kim’s current study. Another is understanding why long-term exposure is creating these injuries. “We know that there are some links, but we don’t know the physiological evidence and exact underlying injury mechanisms that explain the association,” says Kim.
Legal regulations on exposure limits to whole-body vibration exist in the European Union, but the United States does not have such policies. With only recommendations and no consequences to employers, there is little push to limit workers’ exposure in the U.S. Injury compensation claims for musculoskeletal disorders account for the single largest component among all occupational injuries and illnesses in the country. According to Oregon’s Occupational Public Health Program, more than 1,700 cases of musculoskeletal disorders were reported in the transportation, construction, agriculture, and mining industries in 2015.
Near the University of Washington, where Kim received his Ph.D., one large transportation district is paying upwards of $3 million a year in compensation claims regarding lower back pain alone. With self-insured organizations footing the bill, the benefits of implementing new engineering technologies to reduce injuries could exceed the costs.
Bringing something new into the mix, Kim and his team simulate working conditions based on profiles, actual measurements made in mines, construction sites and other locations around the world. The more than 1,200 hours of profiles track the paths of vibrations that drivers experience during their shifts. Some are from as far away as mines in South America.
“The really unique thing is that most lab-based studies have been based upon random vibration or unrealistic sinusoidal (repetitive cycles) vibration,” says Kim. “But here, because we have the large-scale motion platform built with electromagnetic actuators, we can actually feed the vibrations measured from the field to the motion platform. So we can replicate exactly the same motion and vibration that you would feel if you were operating large-scale, heavy vehicles in the mining, construction and agriculture industries and all the way to a passenger car.”
All Shook Up
Kim can program the 6-DOF motion platform to simulate how operators move in all six directions during a work shift. Test subjects experience what it would be like if they were in control of heavy machinery at a mine or in a passenger car on a rough road.
While navigating through potholes or unpaved roads, drivers accept the risk of low-back pain throughout their eight-to-eleven-hour shifts. Prolonged exposure to those types of driving conditions may lead to musculoskeletal pain. The average age of truck drivers is going up, and the industry faces the difficulties of engaging workers to enter a field where their health may be at risk.
One of the main objectives of Kim’s study is to provide physiological evidence that can explain the association between whole-body-vibration exposure and musculoskeletal disorders, especially in the neck and low-back regions. His goal is to contribute to improved engineering interventions (such as seating and machinery design) and better occupational health and well-being for workers.
While field studies typically generate data from drivers, Kim is recruiting test subjects for his laboratory-based studies from the university community and the city of Corvallis. Subjects cannot be pregnant, must be between the ages of 21 and 49 and have no current musculoskeletal issues or low-back disability. During the study, subjects will buckle into a truck seat mounted on the motion stimulator for two 2-hour sessions per day. In total, participants will be in the lab for eight hours a day over four days.
As I was being shaken by the 6-DOF firsthand, the feeling that I could tip off at any moment caused my stomach to drop, like it does on carnival rides. However, imagine that workers have to feel that intensity and pressure on their body for up to eleven hours. Going into work daily and knowing my body would be going through that strenuous experience would be difficult. It was exhilarating for five minutes, but five hours would be a whole other story.
People interested in being involved in this study can contact Kim, director of the Occupational Ergonomics and Biomechanics Lab, at email@example.com.
Editor’s note: Lanesha Reagan is a senior in English from Snohomish, Washington. She is also a member of the OSU Division 1 Women’s Volleyball team.