Objective Individuals performance at the workplace is affected by different adopted postures. Sitting postures are mostly used during office work. Improper sitting postures may cause muscle fatigue and discomfort in the spine and also result in mental workload. Poor posture may result in human errors and delay in information processing. Previous studies have demonstrated the relationship between static sitting postures and cognitive factors such as reaction time to an auditory stimulus. Also, some recent studies have demonstrated the effect of static postures on cognitive performance. To our knowledge, none of the studies had considered the sitting and standing postures effects on cognitive performance simultaneously. The aim of this study was to evaluate cognitive performance during three different static working postures: standard sitting, standing, and self-selected sitting postures.
Materials & Methods This semi-experimental design study was conducted on the twenty-nine healthy students (aged 20-30 years). The non-probability sampling method was selected. All participants provided their written informed consent. Participants with no musculoskeletal disorders, heart disease, spine surgery, and history of depression and stress were selected. Their depression status and level of stress were measured using Beck questionnaire. The study was approved by the Ethics Committee of University of Social Welfare and Rehabilitation Sciences. Subjects performed complex Stroop test and typing activity in an office-like laboratory setting at the University of Social Welfare and Rehabilitation Sciences. Stroop test lasted about 9-12 minutes, and a typing task was also designed for approximately 5 minutes for all subjects. Three random postures were selected based on common postures used in the office. The effects of the postures (standard standing, standard sitting, and self-selected sitting posture) on dependent variables such as total test duration and reaction time to congruent and incongruent stimulus, number of typing words and number of typing error were assessed with Repeated Measures ANOVA. To examine the differences between groups, the paired t-test was used.
Results The results demonstrated that reaction time measure and number of typing error (accuracy) were affected by postures (P=0.001). Post hoc analysis demonstrated that reaction time was significantly different between self-selected sitting posture and standard sitting posture (P=0.001), self-selected sitting posture and standard standing posture (P=0.043), standard sitting posture and standard standing posture (P=0.001). With considering the average amount of reaction time to congruent and incongruent cases, it was observed that there is less reaction time in the standardized sitting posture (M=628.67 ms) compared to the self-selected sitting posture (M=689.41 ms) and standard standing posture (M= 675.16 ms). Also, among the three postures studied a significant difference was observed in the number of typing error words (P=0.001). The number of typing error (accuracy) was lower in this posture compared to the two other postures (M=1.58).
Conclusion This study demonstrates that cognitive performance is affected by working postures. This study demonstrates that standard sitting posture is the best posture. Therefore, it is recommended that sitting posture can help in increasing cognitive performance in the workplace.