A quantitative approach to assess upper limb fatigue in the work field

Abstract

BACKGROUND: Fatigue is a timely topic that has been studied in a laboratory setting, yet still remains difficult to apply in an industrial setting. OBJECTIVE: The aim of the present study was to define possible indicators of fatigue accumulation for an over shoulder level repetitive lifting work while performing lifting in two different ranges (LR1, LR2) in a supermarket. METHODS: Video-based kinematics parameters were estimated and surface electromyography (EMG) of the anterior deltoid muscle was analyzed for nine healthy female subjects. A static biomechanical model to assess the effect of LRs on fatigue and a new fatigue index to allow for the estimation of substantial fatigue onset time (TSFO) were developed. RESULTS: The data showed that fatigue accumulation strongly depends on the LRs. According to TSFO (time to substantial fatigue onset), shoulder muscle fatigue was unexpectedly lower when performing LR1 than LR2. CONCLUSIONS: The study shows a holistic analysis approach, suitable for the design of work/rest ratios in the occupational ergonomics field.