Muscular activity and thermal responses in men and women during repetitive work in cold environments

Abstract

Thermal responses and muscular activity in repetitive work were studied in eight women and eight men at 19 degrees C (thermoneutral) and at 4 degrees C (cold). Furthermore, effect of a heating vest was studied at 4 degrees C. Women had lower (p < 0.05) mean skin temperature compared with men at each thermal condition. Muscular activity (microV) was generally higher in women compared with men, being significantly higher in m. deltoideus (p < 0.05). Women had lower (p < 0.01) maximal isometric strength compared with men, which may have influenced the observed higher muscular activity during work in women. However, compared with thermoneutral, working in cold increased (p < 0.05) muscular activity in the forearm and upper arm extensors only in men. The vest did not significantly counteract the increase in muscular activity. In conclusion, sex differences should be considered when evaluating cold protection and work load reduction in repetitive work in cold environments. Present results indicate that in identical work, sex affects thermal responses and muscular activity during repetitive work in conditions comparable with cooled departments in the food-processing industry. Sex differences should be considered when evaluating cold protection and preventive measures for work load reduction.

Thermal stress, human performance, and physical employment standards

“…Respective values in wrist flexor muscles were 8-12%MEMG, in trapezius 8-14%MEMG, and in shoulder region 6-7%MEMG (Sormunen et al 2006). In a simulated sausage packing work the strain focused on the upper extremity and neck shoulder regions; high values were also found in wrist extensor muscles in females (<20%MEMG) and in males (<16%MEMG) (Sormunen et al 2009). These results are confirmed in the study of Arvidsson et al (2012), where the highest %MEMG values in meat cutters were found in wrist extensor muscles.…”

“…In a cold environment, this translates to greater relative force required to complete a task, or else reduced work capacity or tolerance. Each point represents 8 subjects exceptconditions (Sormunen et al 2009). Higher strain and thus fatigue may be associated to low working temperature, high repetitiveness, awkward postures, and considerable use of force (Christensen et al 2000;McGorry et al 2004;Oksa et al 2002).…”

“…Thus, thermal stress can directly alter operational capacity, both by decreasing work tolerance and also by requiring changes to work scheduling such as increased rest and recovery periods. Cold stress can rapidly reduce manual dexterity (Cheung et al 2003;Heus et al 1995), increase the work involved in balance and maintaining posture (Makinen et al 2005), and increase neuromuscular strain from a given task (Sormunen et al 2009), reducing the total work capacity and increasing the risk for chronic issues such as repetitive strain injuries. Furthermore, cognitive functioning, decision making, and task performance may be impaired by both heat and cold stress (Hancock et al 2007;Pilcher et al 2002), and this can increase the risk of accidents in the workplace.…”

Intermittently Increased Repetitive Work Intensity and Neuromuscular Function in the Cold

“…higher in cold conditions 6) and it seems that women are more susceptible to the increased strain than men 8) . In simulated sausage packing work at 4 °C, the average muscular strain for women was 14% of maximal EMG activity (%MEMG), compared with 12%MEMG among men 8) .…”

“…In simulated sausage packing work at 4 °C, the average muscular strain for women was 14% of maximal EMG activity (%MEMG), compared with 12%MEMG among men 8) . It has also been found that the level of agonist-antagonist coactivation during low intensity repetitive work or static work increases in cold conditions, thus increasing the strain and fatigue of the working muscles 6,7,9) .…”