Prolonged sitting-induced leg endothelial dysfunction is prevented by fidgeting.
Morishima T1, Restaino RM1, Walsh LK1, Kanaley JA1, Fadel PJ2, Padilla J3.
1University of Missouri. 2University of Texas at Arlington. 3University of Missouri email@example.com.
Prolonged sitting impairs endothelial function in the leg vasculature and this impairment is thought to be largely mediated by a sustained reduction in blood flow-induced shear stress. Indeed, preventing the marked reduction of shear stress during sitting with local heating abolishes the impairment in popliteal artery endothelial function. Herein, we tested the hypothesis that sitting-induced reductions in shear stress and ensuing endothelial dysfunction would be prevented by periodic leg movement, or “fidgeting”. In 11 young healthy subjects, bilateral measurements of popliteal artery flow-mediated dilation (FMD) were performed before and after a 3-hour sitting period during which one leg was subjected to intermittent fidgeting (1 min on/4 min off) while the contralateral leg remained still throughout and served as an internal control. Fidgeting produced a pronounced increase in popliteal artery blood flow and shear rate (pre-fidgeting: 33.7±2.6sec-1 to immediately post-fidgeting: 222.7±28.3sec-1; mean±SE; p 0.001) that tapered off during the following 60 sec. Fidgeting did not alter popliteal artery blood flow and shear rate of the contralateral leg, which was subjected to a reduction in blood flow and shear rate throughout the sitting period (pre-sit: 71.7±8.0sec-1 to 3-hr sit: 20.2±2.9sec-1; p 0.001). Popliteal artery FMD was impaired after 3 hours of sitting in the control leg (pre-sit: 4.5±0.3% to post-sit: 1.6±1.1%; p=0.039) but improved the fidgeting leg (pre-sit: 3.7±0.6% to post-sit: 6.6±1.2%; p=0.014).
Collectively, the present study provides evidence that prolonged sitting-induced leg endothelial dysfunction is preventable with small amounts of leg movement while sitting, likely through the intermittent increases in vascular shear stress.