Investigating the Effects of Different Working Postures on Cognitive Performance

Effects of Workstation Type on Mental Stress: FNIRS Study

OBJECTIVE

The purpose of this study is to examine the effect of the workstation type on the severity of mental stress by means of measuring prefrontal cortex (PFC) activation using functional near-infrared spectroscopy.

BACKGROUND

Workstation type is known to influence worker's health and performance. Despite the practical implications of ergonomic workstations, limited information is available regarding their impact on brain activity and executive functions.

METHOD

Ten healthy participants performed a Montreal imaging stress task (MIST) in ergonomic and nonergonomic workstations to investigate their effects on the severity of the induced mental stress.

RESULTS

Cortical hemodynamic changes in the PFC were observed during the MIST in both the ergonomic and nonergonomic workstations. However, the ergonomic workstation exhibited improved MIST performance, which was positively correlated with the cortical activation on the right ventrolateral and the left dorsolateral PFC, as well as a marked decrease in salivary alpha-amylase activity compared with that of the nonergonomic workstation. Further analysis using the NASA Task Load Index revealed a higher weighted workload score in the nonergonomic workstation than that in the ergonomic workstation.

CONCLUSION

The findings suggest that ergonomic workstations could significantly improve cognitive functioning and human capabilities at work compared to a nonergonomic workstation.

APPLICATION

Such a study could provide critical information on workstation design and development of mental stress that can be overlooked during traditional workstation design and mental stress assessments.

Effects of Fatigue on Balance Recovery From Unexpected Trips

OBJECTIVE

The objective was to examine how physical fatigue and mental fatigue affected balance recovery from unexpected trips.

BACKGROUND

Trips are the leading cause for occupational falls that are a multifactorial problem. Recognizing risk factors is the first step in accident control. Fatigue is one of the most common task-related risk factors for occupational falls. Fatigue typically can be divided into physical fatigue and mental fatigue, both of which are common in occupational settings.

METHOD

One hundred eight young volunteers participated in the experiment. They were evenly divided into three groups: no fatigue group, physical fatigue group, and mental fatigue group. Each participant performed four walking trials on a linear walkway at their self-selected normal speed. The first three trials were normal walking trials. A trip was induced to participants in the fourth walking trial using a metal pole. Balance recovery from unexpected trips was characterized by trunk flexion and first recovery step measures.

RESULTS

Recovery step length was smaller and maximum trunk flexion became larger in the mental fatigue group compared with those in the no fatigue group. Physical fatigue did not significantly affect trunk flexion and first recovery step measures.

CONCLUSION

Mental fatigue increased the likelihood of loss of balance. Thus, mental fatigue could be a risk factor for trips and falls. To prevent trip-related falls, interventions should be adopted to prevent prolonged exposures to cognitively demanding activities in occupational settings.

Cognitive and skill performance of individuals at sitting versus standing workstations: a quasi-experimental study

Objectives. This study aimed to assess cognitive and skill performance at sitting and standing workstations among students from Shiraz University of Medical Sciences. Methods. Forty students (20 females and 20 males) participated in this quasi-experimental study. Tests were performed among randomly selected participants over two consecutive days: day 1, the Beck depression inventory and Beck anxiety inventory were used to assess the severity of depression and anxiety in the study participants, respectively, and Raven's general intelligence test was used to measure intelligence quotient; day 2, five performance assessment tests (cognitive performance assessment tests 'n-back', 'Stroop' and 'advanced reaction time'; skill performance assessment tests 'two-arm coordination' and 'Purdue pegboard') were randomly selected and presented to individuals at each workstation (sitting and standing workstations). At the end of each sitting and standing position, the comfort of the workstation was measured using a visual analog scale. Results. No statistically significant difference was shown between sitting and standing positions in terms of 'n-back', 'Stroop', 'advanced reaction time', 'two-arm coordination' and 'Purdue pegboard'. Participants were more comfortable in sitting positions and more easily distracted in standing positions. Conclusions. Sitting and standing positions had no significant effects on participants' cognitive and skill performance.