Master of Science in Industrial Engineering (MSIE)


Mechanical & Industrial Engineering

Document Type



Musculoskeletal disorders (MSDs) are a leading cause of injury in American workplaces which cost the economy billions of dollars each year. Extensive research has shown that job fatigue is one of the causes of MSDs. Allocating frequent and adequate rest break is suggested to be an effective method in mitigating the work overload and fatigue prevention. The objective of this research was to determine rest periods for lifting tasks based on the activity heart rate and by using a set of task variables. Twenty-four university male students took part in this study. The two response variables were perceived level of exertion and the heart rate recovery time (which was the duration needed for the heart rate to reach a steady state after a lifting task). The independent variables were weight of the lift (10 and 20 kg), the frequency of the lift (6 and 9 lifts per minute), and the duration of the lift (5 and 10 minutes). Given the possible treatment combinations, a total of 8 treatments was obtained. Each participant performed one treatment of lifting a box from knuckle to shoulder height at a certain frequency, duration and weight. All eight treatments were equally replicated with three observations per treatment group, giving twenty-four observations. The results of the study indicate that a longer recovery time for the heart rate was needed as the frequency and duration of the lift increased; the effects of both factors were significant. A model for the heart rate recovery time based on significant factors and interactions was developed. The results of the study may be beneficial to the industry as it enables quantitative prediction of a rest period for a lifting task based on task characteristics.



Committee Chair

Aghazadeh, Fereydoun



Included in

Ergonomics Commons