Effect of the different ages and visual display terminal use on repositioning and lumbar muscle activity during continuous sitting.

[Purpose] The purpose of this study was to investigate the effect of different ages and visual display terminal (VDT) use on repositioning and lumbar muscle activity during continuous sitting. [Subjects] Thirteen males two groups: 7 males in their 20s, 6 males in their 40s participated in this study. [Methods] The two groups watched a lecture in a seated position under different conditions. L4 paraspinal muscle activity was recorded using a surface electromyography system. Repositioning was assessed using a video camera and Tekscan system. [Results] The repositioning times decreased significantly in the order to without a VDT in males in their 20s and 40s > with a VDT in males in their 20s > with a VDT in males in their 40s. The L4 paraspinal muscle activity significantly increased in order to without a VDT in males in their 20s and 40s < with a VDT in males in their 20s < with a VDT in males in their 40s. [Conclusion] The results of this study suggest that the number of repositioning movements during continuous sitting could affect lumbar muscle activity and could be an important factor for prevention of low back pain.