ERGONOMIC INVESTIGATIONS OF SIT-STAND WORKSTATIONS FOR COMPUTER-BASED WORK
Increased occupational sedentary behaviors are associated with elevated risks for musculoskeletal-discomfort, cardio-metabolic and cardio-vascular diseases, and pre-mature mortality. Use of sit-stand workstations reduces sitting-time, musculoskeletal-discomfort and fatigue, without impacting productivity. However, physical activity does not increase; there is absence of an optimum sit-stand ratio. This research investigated the potential of a sit-stand-walk intervention (SSWI) to reduce musculoskeletal-discomfort and fatigue, and increase physical activity, without impacting productivity in computer-based work. Three experiments examined efficacy of the SSWI to improve health and productivity at work. The first two experiments with identical research designs were conducted with 80 participants in Ahmedabad, India and 100 participants in Ithaca, United States. Experiments used a between-participants design. Participants performed two-30-minute transcription-tasks after being randomly assigned to one-of-five work-conditions: sit-stand, stand-sit, sitting, standing, and the SSWI. It was hypothesized that the SSWI would reduce musculoskeletal-discomfort, physical fatigue and mental fatigue, without impacting productivity. Variables measured included: self-reported musculoskeletal-discomfort, physical-fatigue and mental-fatigue; productivity operationalized by transcription speed and error. In the Ahmedabad-experiment, the SSWI reported significant reductions in: musculoskeletal-discomfort compared to sitting and standing; physical fatigue compared to standing; and no effect on mental fatigue and productivity. In the Ithaca-experiment, the SSWI reported significant reductions in: musculoskeletal-discomfort compared to standing; physical fatigue compared to all other work; mental fatigue compared to stand-sit and sitting; and no effect on productivity. The third experiment compared efficacy of SSWI in two workstation-configurations: (1) Ergo-Fit - configured according to ergonomic guidelines; (2) Self-Adjusted - configured by workers according to their preference. Using a within-participants design, 36 participants performed two-30-minute transcription-tasks. Variables measured included: self-reported musculoskeletal-discomfort and fatigue; productivity operationalized by transcription speed and error; postural-risks assessed by RULA for seated-work, and REBA for standing-work. Musculoskeletal-discomfort and fatigue were similar; postural risks were significantly lower for Ergo-Fit-configuration; however, productivity was significantly higher for Self-Adjusted-configuration. The SSWI demonstrates an optimal sit-stand-walk ratio – enabling workers to reduce sitting-time, attenuate musculoskeletal-discomfort and fatigue, and increase physical activity, without impacting productivity. Future designs of work should consider the physiological, cognitive and psychological benefits of frequent, short-bouts of standing and movement to improve worker health, well-being and productivity.
Psychology; Sit-Stand Workstations; Active Breaks; Musculoskeletal Discomfort; Postural Transitions; Productivity; Fatigue; Occupational safety; Design
Santiago-Irizarry, Vilma; Swallow, Khena M.
Design and Environmental Analysis
Ph.D., Design and Environmental Analysis
Doctor of Philosophy
dissertation or thesis