Rheologic changes in venous blood during prolonged sitting.

We examined blood rheologic changes, mainly blood viscosity, during long-term quiet sitting. Samples of blood were obtained from the arm and foot veins of the healthy adult male volunteers before and after 2 h of quiet sitting. Blood viscosity, was immediately determined with an oscillation viscometer, and blood count and blood chemistry were analyzed. We found that the viscosity in blood from a foot vein but not from an arm vein increased significantly after 2 h of sitting. Our results show that 2 h of quiet sitting can increase thrombotic tendency locally in the leg but not systemically and suggests the importance of measuring focal venous blood viscosity.