ABSTRACT
Muscle activity was assessed by sEMG technique (TM Trigno Wireless System, DelSYS), for 15 minutes (dominant and not dominant trapezius muscle of each participant) (Kallenberg, Schulte, Disselhorst-Klug, & Hermens, 2007). The location of the muscle was determined taking into account two landmarks: acromion and C7 vertebra. The electrode was set at 50% of the imaginary line joining these two points. The skin of the participants was prepared in order to ensure a good contact with the electrode. Sandpaper was used to remove small surface residues (SENIAM, nd). The skin was cleaned with cotton with 70% ethyl alcohol by doing a slight abrasion until the skin is rosy (Hermens et al., 1999) and dried before placing the electrode. The electrode was fixed on the skin by an appropriate adhesive tape. The record of the amplified signals was achieved by the use of EMGworks Acquisition System version
1 INTRODUCTION
Fatigue is defined as the inability of the musculoskeletal system to generate high levels of muscle strength, or maintain those levels over time. In the occupational setting, could be caused by repetitive work, short work cycles, and even by localized muscle loads. Exposure to cold thermal environments can reduce muscle performance and cause deficiencies in the functioning muscle. In several studies, muscle fatigue has been evaluated through electromyography (Sakurai et al., 2010). Surface electromyography (sEMG) is the technique usually selected by researchers because of its non-invasive nature. It is considered a valuable tool in the ascertainment of muscle fatigue (Kilby & Prasad, 2013; Erja Sormunen et al., 2009). In assessing the perceived fatigue by workers, have been developed psychophysical scales that allow estimating the workload subjectively felt by the individual while performing an effort. The main goal of this research is to analyse fatigue evolution performing a repetitive task in two different thermal conditions using surface electromyography.
