Prolonged leg bending impairs endothelial function in the popliteal artery

Area of Science:

• Vascular Physiology
• Endothelial Function
• Blood Flow Dynamics

Background:

• Uninterrupted sitting is known to impair vascular endothelial function in the lower extremities.
• The specific factors causing this impairment, particularly those related to joint flexion, remain unclear.

Purpose of the Study:

• To investigate if prolonged hip and knee joint flexion, mimicking sitting posture, impairs endothelial function in the popliteal artery.
• To determine the role of low shear stress and disturbed blood flow in this impairment.

Main Methods:

• Bilateral popliteal artery flow-mediated dilation (FMD) measurements were taken in 12 healthy subjects.
• One leg was kept bent at 90-degree hip and knee angles, while the other remained straight for 3 hours in a lying position.
• Popliteal artery blood flow, mean shear rate, and FMD were assessed before and after the intervention.

Main Results:

• The bent leg showed a significant reduction in popliteal artery blood flow and mean shear rate during the 3-hour period.
• Popliteal artery FMD was markedly impaired in the bent leg post-intervention (pre: 6.3% vs. post: 2.8%, P < 0.01).
• The straight leg exhibited only a slight decline in blood flow and no significant change in FMD (pre: 5.6% vs. post: 7.1%, P = 0.24).

Conclusions:

• Prolonged leg bending leads to endothelial dysfunction in the popliteal artery.
• This dysfunction is likely caused by exposure to low and disturbed blood flow due to arterial angulation.
• Sustained periods of bent and immobile legs, regardless of posture (sitting or lying), may be detrimental to leg vascular health.