Résumé
Recently, a standing desk is being installed as a behavior change strategy to reduce sitting time in the workplace. However, the standing posture has been suggested to decrease forehead oxygenated hemoglobin (oxy-Hb), which might impair task performances. Therefore, we examined whether prolonged standing impairs speed and accuracy of computer subtraction task associated with a decrease in forehead oxy-Hb. Nine healthy young males completed 4 × 15-min computer tasks under two conditions, i.e., sitting and standing. In the computer tasks, all subjects were required to subtract a two-digit number from a four digit number written on the paper and to input the answer to the answer colomn on the computer. Task performances were evaluated as the number of achievements and accuracy rate every 15 minutes. Moreover, oxy-Hb and deoxygenated-hemoglobin (deoxy-Hb) in the site of left forehead area and lower limb were monitored throughout the experimental period by near-infrared spectroscopy. Forehead oxy-Hb was significantly associated with the number of achievements during computer tasks (p < 0.001). In addition, forehead oxy-Hb and task performances did not differ between sitting and standing. The number of achievements of subtraction task under standing condition was significantly decreased as time proceeds. Our results demonstrate that prolonged standing might impair computer subtraction task performances irrespective of the change in forehead oxy-Hb.