Semester of Graduation

FALL 2018


Master of Science in Industrial Engineering (MSIE)


The Department of Mechanical and Industrial Engineering

Document Type



Manual materials handing (MMH) is the main cause and concern for injuries in the working population which lead to musculoskeletal disorders (MSDs). MSDs significantly contribute to the cost of workers’ compensation and loss of productivity, thus impacting economy of the United States. MSDs are mainly caused due to over exertion and fatigue experienced by workers involved in manual materials handling. In addition to over-exertion and fatigue, lack of short and frequent rest intervals between tasks contributes to the risk of MSDs. The objective of this research was to study the effect of rest period on muscle fatigue using electromyography (EMG) during manual lifting. The median frequency of the EMG signal, heart rate (HR), Borg’s rating, arm lift and hand grip strength were used as measures of fatigue due to rest periods (zero rest, 5, 10 and 15 min) during the manual lifting task. The physical activity ratings (PAR), body mass index (BMI) and hours of sleep were the covariables studied. Fifteen male participants took part in this study. Each participant performed one treatment per day of lifting a box weighing 15kg. from knuckle to shoulder height at a fixed of frequency 12 lifts per minute for 13 minutes duration. The EMG, heart rate and Borg’s scale rating were used to record the perceived level of exertion and determine whether the duration of rest was sufficient to recover from fatigue during manual lifting. Statistical analysis was performed to test the hypotheses defined for significance. The results showed at least 10min of rest was required, and 10min was optimum for bicep brachii muscle to recover from fatigue. The study concluded EMG and HR were better measures of muscle fatigue than Borg’s rating. This study would be beneficial to the industry in work design, which enables defining rest periods between continuous lifting tasks.



Committee Chair

Aghazadeh, Fereydoun