It’s not surprising that farmers experience back pain more often than most of us. They work long hours, lift massive loads, and hop on and off large tractors and trucks. But one unexpected source of back pain comes from the vibrations caused by driving heavy equipment.
University of Saskatchewan student Xiaoke Zeng worked first-hand with farmers to study the health effects of whole-body vibration. “Driving is such a regular thing they do every day and they’re not only driving one piece of equipment, they’re transferring very frequently,” says Zeng.
“Vibration level definitely matters. There’s a connection between the frequency of how something vibrates and the impact it has on the human body.”
All of us experience vibration in various ways, driving our cars or taking the bus to work. But since farmers are constantly driving large vehicles on bumpy terrain, their vibration exposure can pose a higher threat.
Working at the National Agricultural Industrial Hygiene Laboratory under CFI-funded researcher and Canada Research Chair in Ergonomics and Musculoskeletal Health, Catherine Trask, Zeng and a group of other students, collected data from 54 Saskatchewan farmers in 2015.
The team looked at eight different types of equipment: tractors, combines, grain trucks, ATVs, skid steers, sprayers, pickup trucks and swathers. They also studied the vibrations caused by riding horseback.
Special seat pads with sensors were attached to farming equipment to record vibration levels while farmers worked. The recorded data was then taken back to the lab to be analyzed.
Farmers were also filmed doing various tasks and answered questions about their experience with back pain and any steps they took to reduce it.
The effect of a piece of vibrating farming equipment is akin to an opera singer singing an especially high note near a wine glass. If the vibration of her voice reaches a certain frequency the wine glass will break. Just like the wine glass, the human spine is prone to damage if it vibrates at a certain frequency.
Ergonomics research shows the human spine is most at risk of damage when it is exposed to vibrations in the range of 2.5 to 10 hertz — or 2.5 to 10 vibrations per second. The closer the frequency of the vibration of a piece of equipment is to this frequency, the more likely it is to cause resonance, especially on the spine, which can lead to lower back pain.
Trask says that diesel engines produce vibrations at a frequency that falls within this damaging range. Surprisingly, Zeng says, they found farmers who rode horses recorded the most damaging vibration levels at a frequency of 2.5 to four hertz. However, she said, more research is required to confirm the effects of horseback riding on the human spine.
The amplitude of the vibration, which is the height you’re bouncing up and down while riding, is also an important factor in causing back pain.
The researchers found that among farming equipment small machines such as ATVs or skid steers produced the highest amplitude per vibration. Large machinery like combines produced lower levels of amplitude.
In addition to these factors, the longer a farmer spent driving any machine, the more spinal damage it was likely to cause.
Trask stresses the most important takeaway is that farmers take breaks often to stand up, walk and stretch.
Trask’s team hopes this research will contribute to building better, more ergonomically safe farming equipment to mitigate the effects of vibration exposure.
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