Study yields new insight into protecting the health and well-being of agricultural workers

Agriculture is one of the most hazardous industries in terms of both fatalities and non-fatal injuries, with only about two out of every 10 agriculture workers going a full year without developing musculoskeletal disorders such as low back pain or rotator cuff tears.

Now, new research that blends objective data with personal perceptions regarding this work gives insight into ways to keep these workers safer.

The study was done by Jeong Ho “Jay” Kim, PhD, an occupational ergonomics and biomechanics expert with the Texas A&M University School of Public Health, and Jaehyun Park, PhD, from South Korea’s Konkuk University. It was supported by Konkuk University and published in the International Journal of Industrial Ergonomics.

“Ergonomics is about adapting the task to the worker instead of the other way around,” Kim said. “By learning more about how agricultural workers use their upper limbs—shoulders, arms, elbows, forearms, wrists and hands—as they work, we can assess the physical and mental effort required and their risk of injury or fatigue in these areas.”

To gather the objective data, the researchers used an exoskeleton that had a torso harness and protective upper arm plates, as well as an FDA-approved, commercially available wearable sensor.

While exoskeletons are a promising ergonomic solution for reducing the physical strain of workers in industries that require repetitive motions or sustained exertion—such as forestry, construction and logistics—Kim said little is known about their effectiveness in the unique physical demands of agricultural work.

“Our approach was unique in two ways,” Kim said. “The exoskeleton we used was intended for workers in manufacturing, so the agriculture application was new. In addition, the vast majority of research on agricultural work focuses on things like workers’ muscle activity or exertion, which measures biomechanical stress but provides little information on actual overall workload. We measured workload through their electrodermal activity.”

Biomechanical stress is the internal impact that exercise or other movements have on tissue. On the other hand, electrodermal activity, also known as skin conductance, reflects activity in the sympathetic nervous system and sweat glands and increases with emotional or physical stimulation or exertion.

Compared to other stress measuring techniques such as electromyography and heart rate, its sensitivity to changes in the skin’s electrical response and the detailed information it provides about these changes make it a better tool for assessing both physical and mental stressors.

To gather the subjective data, the researchers asked participants to describe their current pain or pain history by body part before the study began, then rate their perceived levels of exertion (low, medium or high) after each task performed in the study.

The study was done between August and December 2024 in laboratories at Konkuk University and involved 12 males and 12 females from 18 to 30 years of age. The participants were placed in random groupings that had 16 total experimental conditions: two simulated pruning and harvesting tasks either with or without the exoskeleton at four working heights: knee, elbow, shoulder and head.

“We chose pruning and harvesting because we learned in our consultations with agricultural workers that these were particularly labor intensive, especially in in fruit crop management,” Kim said. “They both require repetitive and strain-inducing tasks: the sustained gripping and cutting motions used in pruning and the repetitive reaching, grasping and placing motions used in harvesting.”

To assess workload, the research team measured workers’ electrodermal activity during tasks and their self-reported perceptions afterward.

“Our statistical analyses found that skin activity helps explain almost half of the differences in how much work people do,” Kim said. “Skin response data can tell us a lot—almost half—about someone’s workload.”

In addition, he said the model was very accurate in determining average workload, but less accurate in detecting low workload.

Kim said the results are encouraging and largely consistent with previous findings that integrating objective, technology-based measurements with subjective, experience-based workload ratings provides more accurate data.

“The bottom line is that integrating the electrodermal activity model with subjective workload ratings is particularly well-suited for real-world agricultural and industrial settings,” Kim said. “It provides non-invasive, continuous and objective monitoring that could help us find ways to improve worker safety and productivity.”