A farmer’s back pain waits with the patience of a stone, perpetually at field’s edge. In 2009, Perry Galloway lay face-up on the cold concrete floor of his farm office for days, barking orders and conducting business, desperate for relief from agony akin to sand paper on raw nerves. With crop season bearing down, he knew the inescapable reality—no matter the pain, the farm show must go on.
Back pain is toe-tagged to agriculture work. Pushing, pulling and lifting are the oft-cited culprits, but silently hiding behind these usual suspects may be the chief instigator: vibration. A recently released study from the University of Iowa examines levels of whole-body vibration (WBV) absorbed during operation of agriculture vehicles. The innovative analysis is highly suggestive that over the course of lifetime exposure, WBV may be devastating for particular growers.
Whole Lotta Shakin’ Goin’ On
Over five years, from 2011 to 2016, Nathan Fethke and a team of researchers attached sensors to over 100 agriculture machines and vehicles in the Midwest: ATVs, combines, forklifts, skid loaders and tractors. The data was collected on 50 operations predominantly in Iowa, but included locations in all neighboring states.
Fethke, a biomedical engineer and associate professor in the Department of Occupational and Environmental Health at the University of Iowa, College of Public Health, placed two accelerometer sensors in each farm vehicle to detect vibration levels. A specialized rubber disc was placed on top of each seat to measure up-down, forward-back and side-to-side movement. The second sensor was attached to the floor solely to record up-down movement. The results were ominously clear and point toward the deleterious effect of long-term WBV exposure. Using the EU’s WBV exposure limit standards as a guide, Fethke’s data showed almost 60% of machines delivered a full day’s dose of WBV in less than two hours. According to Fethke’s research, farm operators drink directly from the WBV firehouse.
The longer an operator is in a vehicle, the greater the dose of WBV, a significant factor at planting or harvest, when farmers can often spend 10-15 hours per day driving machinery for weeks or months. “The effects of whole-body vibration shouldn’t be underestimated,” Fethke urges. “Think about holding the top of a Slinky with your hand. When you move the Slinky up and down at the right frequency, the slightest motion at the top creates huge movements at the bottom of the spring. Basically, the incoming motion is smaller than the outgoing motion. The spine and back can respond to vibration in the same manner.”
“The data supports a large body of research that says workers spending long hours operating vibrating equipment are highly susceptible to injuries over the course of a career—particularly back injuries,” Fethke adds. “This absolutely applies to complicating old injuries or contributing to new ones.”
The study showed WBV varies according to vehicle type. ATVs transmitted the highest levels of WBV, followed by heavy utility vehicles, tractors, pick-up trucks and semi-trailers. Combines (cotton pickers were not included in the study) afforded the most protection from WBV, likely due to vehicle mass and improved seat suspension systems, according to Fethke.
A Week of Hell
On a sand ridge perched between the Cache and White rivers, Galloway, 51, grows corn, grain sorghum, rice, soybeans and wheat on 8,000 acres in Gregory, Ark., roughly 80 miles northeast of Little Rock. The Woodruff County producer’s overall operation also includes Hefty Seed Co. and Broadview Aviation.
From the age of eight, Galloway has operated ag machinery. His formative years were a blur of farm work, football, and the bulletproof antics of youth. Following college graduation, he returned full-time to daily farming’s pushing, pulling, lifting, exerting and driving. By 1998, Galloway’s lower back was in open rebellion, and he bounced from one flare-up to the next.
“Gradually, the pain kept building, kind of a numbing soreness in my lower left back I had to deal with year by year. I just lived with it as part of farming. It wasn’t crippling, but it got really bad sometimes. I remember having to move an auger by myself, pushing and straining; I was in hell for a week straight after.”
In 2004, Galloway returned from a crop dusting run and executed a typical landing on a grass strip, but the vibration hammered his lower back. “It was another step toward surgery. It didn’t matter how careful I was; year over year my back was getting progressively worse.”
In 2008, Galloway went under the knife related to a bulging disc at the L5-S1 level, followed by a return to the rigors of farm work; a year later he was back in surgery. A second back operation was performed in 2009, again followed by a return to farm work; ditto—two years later Galloway was on the operating table again for a third surgery.
“Three surgeries are bad enough, but I have to very careful because the next surgery will be far more extensive, but on my farm, I don’t have three or six months to recover. Sometimes when I get sore, I can’t help but wonder if I’m on the edge to that big surgery.”
Ring Like a Bell
Galloway is not a farming exception, according to Fethke’s research. The frequency of back injuries related to agriculture work is remarkably high: “Regardless of the setting, we find 30% of farmers with at least one episode of back pain that limited their work activity just during the past year. Over the course of a career, the figure approaches 90% of farmers,” Fethke details.
Compounding the issue, the myriad ways a farmer can encounter back pain are exacerbated by the consistency of WBV and its long-term consequences. “There are clear associations between greater exposure to vibrations and greater frequency back pain episodes,” Fethke explains.
David Wilder is a professor in the Department of Biomedical Engineering at the University of Iowa, College of Engineering, and an internationally renowned authority on back issues and occupational health, particularly in relation to how WBV and the seated posture can affect the back. Hyperbole excluded, Wilder is an expert in the field.
“Sitting while operating a tractor or other farm equipment is not a simple task. It often demands many changes in the farmer’s posture. When a farmer is sitting slouched forward in a tractor, especially with no lumbar support, all the fibers in the back of his lower back’s discs are stretched out and then tugged repeatedly because of the up and down, side to side motion of the tractor. The fibers have characteristics like the metal in a paper clip. Bend a paper clip a little bit back and forth for innumerable cycles and it’s just fine, but bend it a little more, repeatedly, and at some point it will break through metal fatigue. The disc’s fibers are similar. You can repeatedly stretch them, but when you stretch them too far, too many times, they reach a limit and they fail.”
“Drive down a dirt road, hit a washboard, and your voice shakes,” he continues. “The body is highly sensitive to this movement. Sitting inside agriculture machinery can subject your disc fibers to amplified or increased stretching due to resonant vibration. A National guitar uses a built-in resonator to amplify sound, without using an electric amp. Resonant vibration works great on instruments, but it is extremely tough on humans. With the proper vibration conditions, the human body can resonate or ring like a bell.”
Wilder further illustrates the point: “Ever ride in a vehicle that hits 80 mph and begins to shake like crazy? You already know to slow down or the structure will be damaged. So what about a farmer’s body? Logically, the rougher the ride vibration in a poor seated posture that people are exposed to long-term, the greater is the likelihood of severe back trouble.”
Tale of the Tape
Fethke acknowledges back pain as inherent to farming, but says the consequences of WBV can be minimized. “Don’t underestimate the value of good seating and suspension. Seats wear down and bottom out over time, especially with the abundance of old tractors. It may just be a simple adjustment with springs or a hydraulic damper. Take the time to clean and grease under the seat. Paying attention to and maintaining the seat and its suspension should be part of the overall machine maintenance routine.”
“We are not necessarily advocating for more regulations on retrofitting or manufacture. We’re just providing the data for anyone to use and, hopefully, increase farmers’ awareness about ways to protect themselves from the long-term effects of WBV exposure,” he adds.
According to Wilder, Fethke’s study (Whole-Body Vibration and Trunk Posture during Operation of Agricultural Machinery) is significant and valuable because it “identifies environments that could use improvement. Farmers are tough and they know the crops must be finished regardless of circumstance. However, the causes of back pain can be alleviated. The best and least expensive place to start is with proper seating—something that allows for good posture and shock absorption.”
As for Galloway, he offers advice for other farmers. “This is part of our lifestyle and we all know that. You have to drive for long hours, pick up 100 lb. items, and push objects far heavier every single day, but I’d tell guys, especially young farmers, to try hard to be wise. Be conscientious to prevent back trouble and you can possibly forego the issues I have in middle age.”
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