Biomechanical factors during common agricultural activities: Results of on-farm exposure assessments using direct measurement methods

Abstract

Agricultural work is associated with increased risk of adverse musculoskeletal health outcomes. The purpose of this study was to quantify exposure to biomechanical factors among a sample (n = 55) of farmers in the Midwest region of the U.S. while they performed a variety of routine agricultural activities, and to compare exposure levels between these activities. Surface electromyography was used to estimate activity levels of the erector spinae, upper trapezius, forearm flexor, and forearm extensor muscle groups. Simultaneously, inertial sensors were used to measure kinematics of the trunk, upper arm, and wrist. In general, lower muscle activity levels, less extreme postures, and slower movement speeds were observed during activities that involved primarily the use of agricultural machinery in comparison to manual activities, suggesting a potential advantage of mechanization relative to musculoskeletal health. Median wrist movement speeds exceeding recently proposed exposure thresholds were also observed during many manual activities, such as milking animals and repairing equipment. Upper arm postures and movement speeds did not appear to confer excessive risk for shoulder-related outcomes (on the whole), but interpretation of the results is limited by a sampling approach that may not have captured the full extent of exposure variation. Not surprisingly, substantial variation in exposure levels were observed within each agricultural activity, which is related to substantial variation in the equipment, tools, and work practices used by participants. Ultimately, the results of this study contribute to an emerging literature in which the physical demands of routine agricultural work have been described on the basis of sensor-based measurements rather than more common self-report or observation-based approaches.

Keywords:

• Agriculture
• ergonomics
• kinematics
• surface electromyography

Acknowledgments

This study was supported by US Centers for Disease Control and Prevention (CDC)/National Institute for Occupational Safety and Health (NIOSH) through a cooperative agreement with the Great Plains Center for Agricultural Health (CDC/NIOSH grant no: U54OH007548). The Heartland Center for Occupational Health and Safety (CDC/NIOSH grant no: T42OH008491) and the Deep South Center for Occupational Health and Safety (CDC/NIOSH grant no: T42OH008436) provided additional support. We greatly appreciate the participants’ willingness to engage in this research project. We also wish to acknowledge the following research staff and students for their contributions to the data collection effort: Bryan McGivern, Katie Hofer, Joseph Watabe, Maya Ramaswamy, and Mahmoud Metwali.