Objective Methods for Characterizing Physical Exposures which may contribute to Work-related Musculoskeletal Disorders in Agricultural Workers

Thesis (Ph.D.)--University of Washington, 2016-08

US Migrant farmworkers perform physically-demanding work but are less likely to report poor working conditions, which exposes them to greater risk for musculoskeletal disorders (e.g., prolonged non-neutral postures, repetitive motions and forceful exertions). Technology such as harvest-assisted mobile orchard platforms can increase worker efficiency, but the potential impact on musculoskeletal health effects is unclear. The existing methods to assess ergonomic risk factors are not suitable to examine agricultural work due to the variability observed in the field. The goal of this dissertation is to develop methods to characterize these musculoskeletal health risk exposures using objective measures including kinematic (arm movements) and physiological (muscle fatigue and muscle activity) data collected in the field using inclinometer and electromyography, respectively. Subjective measures are also collected using the Borg RPE and Borg CR10 scales to assess perceived overall body exertion and local body part fatigue, respectively. These exposure assessment methods are used to evaluate and compare different apple harvesting methods in Washington State. The relationship between the objective and subjective measures are examined to assess whether objective measures, which are cumbersome to collect, can be replaced with subjective measures. The findings suggest that mobile platforms could reduce the kinematic measures of musculoskeletal health risk exposures but may not reduce physiological impact observed in muscles. Subjective measures provided different results from objective measures; therefore, one could not replace the other. The potential benefits of this research relate to improve work environment for farmworkers, which will ultimately improve their overall health and well-being.