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Endothelial function following prolonged sitting –Connecting the dots between sedentary life and CVD

Endothelial dysfunction following prolonged sitting is mediated by a reduction in shear stress.

Restaino RM, Walsh LK, Morishima T, Vranish JR, Martinez-Lemus LA, Fadel PJ, Padilla J.


We and others have recently reported that prolonged sitting impairs endothelial function in the leg vasculature; however, the mechanism(s) remain unknown. Herein, we tested the hypothesis that a sustained reduction in flow-induced shear stress is the underlying mechanism by which sitting induces leg endothelial dysfunction. Specifically, we examined whether preventing the reduction in shear stress during sitting would abolish the detrimental effects of sitting on popliteal artery endothelial function. In 10 young healthy men, bilateral measurements of popliteal artery flow-mediated dilation (FMD) were performed before and after a 3-hour sitting period during which one foot was submerged in 42°C water (i.e. heated) to increase blood flow and thus, shear stress, while the contralateral leg remained dry and served as internal control (i.e., non-heated). During sitting, popliteal artery mean shear rate was reduced in the non-heated leg (pre sit: 42.9±4.5s-1, 3 hr sit: 23.6±3.3s-1; p<0.05) but=”” not=”” in=”” the=”” heated=”” leg=”” (pre=”” sit:=”” 38.9±3.4s-1,=”” 3=”” hr=”” sit:=”” 63.9±16.9s-1;=”” p=””>0.05). Popliteal artery FMD was impaired after 3 hours of sitting in the non-heated leg (pre sit: 7.1±1.4% vs. post sit: 2.8±0.9%; p<0.05) but=”” not=”” in=”” the=”” heated=”” leg=”” (pre=”” sit:=”” 7.3±1.5%=”” vs.=”” post=”” sit:=”” 10.9±1.8%;=”” p=””>0.05). Collectively, these data suggest that preventing the reduction of flow-induced shear stress during prolonged sitting with local heating abolishes the impairment in popliteal artery endothelial function. Thus, these findings are consistent with the hypothesis that sitting-induced leg endothelial dysfunction is mediated by a reduction in shear stress.

Am J Physiol Heart Circ Physiol. 2016 Jan 8

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