Muscle fatigue assessment of prolonged standing work in food service workers during typical work operations

Abstract

Over 2.2 million individuals are employed as wait staff in the US, and experience considerable number of musculoskeletal disorders (MSD’s) each year. Little is known about how their occupation impacts the risk factors associated with MSD’s (Wills et al., 2013). The impact of prolonged standing, particularly in occupations requiring long work shifts has been shown to cause significant musculoskeletal discomfort and disorders (King, 2002). The risk of fatigue and developing a musculoskeletal injury is a growing problem in the food service industry; and modifications must be made to the workplace or work tasks to reduce reported injuries. Recent advances in technology, including wireless physiological and biomechanical wearable sensors, have allowed researchers to better study the impact of standing on posture and fatigue in the work environment. Fatigue can be estimated using various methods including questionnaires and force-based estimates. Surface electromyography (sEMG) has also been used extensively to monitor fatigue. SEMG provides an estimate of muscle activity and signal parameters have been used to accurately estimate muscle fatigue. The purpose of this thesis was to examine muscle fatigue of the lower legs using sEMG during prolonged standing. Specifically, fatigue measures including questionnaire, force data and sEMG were recorded and compared pre-and post a typical work shift. There were no significant changes in root mean square (RMS) or median frequency (MDF) in any muscles across all time points. Reported discomfort post shift increased in the right knee, and feet. The data indicated that although there were no significant changes in EMG variables workers may have experienced increased fatigue or discomfort as shift time increased.