Back pain can be attributed to whole-body vibration

Farmers and back pain go hand in hand. It can be difficult to pinpoint the exact cause, and many who suffer assume it just comes with the job. In fact, according to the National Institutes of Health, lower back disorders are the most common musculoskeletal problems among farmers, who have a higher rate of these symptoms than the general population.

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Many cases of back pain can be attributed to whole-body vibration (WBV), which occurs when the shaking motion of a vehicle is transmitted through the body of the operator, potentially damaging the musculoskeletal, circulatory, and nervous systems.

Other symptoms include a shaky feeling or loss of balance after driving, headaches, muscle cramping, dizziness, increased heart rate, and high blood pressure.

Measuring WBV

Nathan Fethke, associate professor of occupational and environmental health at the University of Iowa College of Public Health, led a study that examined 50 farmers' WBV exposure while operating several different types of farm machinery.

"Exposure to whole-body vibration is a key occupational risk factor for back pain, which is common among agricultural workers," he says.

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The study placed sensors on the floor and seat of more than 100 pieces of equipment, including combines, tractors, forklifts, skidsteer loaders, and all-terrain vehicles.

By comparing floor and seat sensors in each vehicle, Fethke was able to determine how well the seat protected the operator from machinery vibrations.

The study found tractors and heavy utility vehicles exhibited vibration levels about twice as high as combines. Fethke says the lower levels in combines were likely because of a combination of their mass and the sophisticated seat suspension systems found in many models. "The combine seats reduced by half the amount of vibration measured at the floor," he says.

Tractor seats didn't dramatically reduce WBV, which Fethke says could be attributed in part to seats not being adjusted to the operator's weight or to wear and tear on the seat suspension.

Vibration is transmitted through the floor, seat, and seat back and is affected by vehicle type, seat type, speed, and terrain.

Acceptable Levels

The U.S. Occupational Safety and Health Administration (OSHA) has not established standards related to WBV exposure. Fethke says the study compared average vibration levels to recommendations made by the American Conference of Governmental Industrial Hygienists, which are similar to limits set by the European Union.

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Those recommendations include a maximum number of hours per day workers may be exposed to WBV: 11.5 hours in a combine, 8.5 hours in a heavy road vehicle, 6 hours in a tractor, 5 hours in machinery like bulldozers, and less than 4 hours on an ATV.

However, the University of Iowa study showed that nearly 30% of machines tested reached EU action level — where the risk of health effects increases — after only two hours.

According to a separate study conducted in Sweden, pregnant women should be especially careful with WBV exposure. It found that even at EU permissible levels, WBV was associated with an increased risk of preterm birth.

What Can Farmers Do?

It's not at all uncommon for farmers to spend 12 or more hours per day in the tractor or combine during the planting and harvest seasons, and cutting back on that time isn't a realistic option. Still, the risk of injury from WBV can be reduced.

Fethke advises all farmers to check seat suspension systems to make sure they're working properly. They should be greased regularly and adjusted for each operator. If the seat bottoms out, consider replacing it.

He also says posture has an impact on WBV's effects. "It is often necessary to lean far forward or look to the side or behind the equipment for visibility purposes," he says. "However, these twisting postures change how the body responds to vibration and can increase the risk of back problems down the road." Operators should be aware of posture and avoid slouching forward.

The Great Plains Center for Agricultural Health offers these additional practices to reduce symptoms from WBV:

• Reduce vehicle speed over rough terrain.
• Maintain on-farm roads and fill potholes.
• Take regular breaks when operating equipment.
• Keep tires inflated and maintain suspension systems.
• Use a backrest with lumbar support.
• Avoid lifting immediately after long periods of driving.
• Communicate recommendations to employees.

Talk to Your Doctor

See your doctor if you are experiencing back pain or other symptoms, and specifically mention your exposure to vibration. As common as WBV is, it isn't always discussed in medical and nursing school. Amy Kincannon, MSN, RN, is a farmer and assistant professor of nursing at the University of Louisiana Monroe Kitty DeGree School of Nursing. She learned about WBV from AgriSafe's Nurse Scholar program in January and was able to put the things she learned into practice right away while staffing a booth at an agricultural expo.

"I asked every ag worker who came through if they had heard of WBV and not a single one had," she says. "It was really interesting to be able to teach them about something I had just learned the day before."