Master of Science, The Ohio State University, 2023, Industrial and Systems Engineering

Introduction: Musculoskeletal disorders in the workforce are highly prevalent, especially in material handling operations. In addition to completing physically demanding work that is required in this domain, workers must also manage concurrent mental demands present in their tasks. Few studies have examined the effect of concurrent mental demands in occupationally-relevant tasks. This study attempted to fill this void by quantifying the effects of varying degrees of cognitive loads and task precision demands on a material handling task by examining these effects on the kinematics and muscle activity of the trunk and shoulders. Methods: Twelve subjects lifted and placed a 5 kg box on a rack at one of three destination heights (low, middle, high) while under a simultaneous cognitive load (no load, simple load, complex load) and/or precision constraint (low precision, high precision). Cognitive load consisted of time-based arithmetic questions where participants were tasked with determining the amount of time remaining from a given time to a target time (e.g., Get to 4:00 PM from 3:15 for simple load or get to 4:10 PM from 3:27 PM for complex load). The primary dependent measures were the angular velocities of the trunk and shoulders as well as muscle activity in the erector spinae, rectus abdominus, external oblique, latissimus dorsi, and anterior deltoid muscles. Results: Significant decreases in angular velocities for both higher cognitive load complexities and higher precision conditions were observed. Additionally, lower 90th percentile normalized muscle activity values were observed as complexity and precision increased. Cumulative muscle activity, however, increased with these increases in complexity and precision. Conclusions: This study examined the impact of varying levels of cognitive and precision conditions on muscle activity and kinematics of the trunk and shoulders. Results indicated that increased complexity and precision led to longer lift t (open full item for complete abstract)

Committee: Carolyn Sommerich (Committee Member); Steven Lavender (Advisor) Subjects: Behavioral Sciences; Biomechanics; Engineering; Health Sciences; Industrial Engineering; Kinesiology; Occupational Safety