Sitting-induced Endothelial Dysfunction Is Prevented in Endurance-trained Individuals.

Abstract

Prolonged sitting impairs leg endothelial function, which seems to be mediated by a sustained reduction in blood flow-induced shear stress. However, whether regular endurance training is effective in preventing sitting-induced leg endothelial dysfunction remains largely unknown. Herein, we tested the hypothesis that sitting-induced leg endothelial dysfunction is prevented in high endurance-trained individuals. The endurance-trained group comprised 10 male collegiate cyclists, and the untrained group comprised nine men with no regular endurance training. Peak oxygen uptake (V˙O2peak) was initially determined in all participants using incremental exercise test (37.9 ± 4.7 mL·min·kg in the untrained group versus 60.8 ± 3.6 mL·min·kg in the endurance-trained group). At second visit, the popliteal artery flow-mediated dilation (%FMD) was assessed before and after a 3-h sitting period. During the sitting period, the popliteal artery diameter and blood velocity were measured every hour. The popliteal artery blood flow and shear rate were significantly and similarly reduced during the sitting period in both groups (P < 0.001). In a 3-h sitting, a significant impairment in popliteal artery %FMD was observed in the untrained group (P = 0.003), but it was prevented in the endurance-trained group (P < 0.196). In conclusion, the present study revealed that sitting-induced leg endothelial dysfunction is preventable in endurance-trained individuals.