Ultrasonographic analysis of effects of seated stretching on popliteal venous haemodynamics after prolonged sitting

Objective To quantify changes in popliteal vein haemodynamics after 1 hour of sitting and to determine whether a brief seated stretching protocol can improve venous return while maintaining the seated posture. Methods In this prospective repeated-measures study, 34 healthy adults aged 18-30 years (19 men, 15 women) underwent bilateral popliteal vein assessment after 60 minutes of sitting and again after completion of a brief seated stretching protocol comprising heel raises and hamstring/calf stretching. B-mode and triplex Doppler ultrasound were used to measure popliteal vein cross-sectional area (CSA) and time-averaged mean velocity (TAMV). Volume flow rate (VFR) was calculated as CSA × TAMV. Results For the whole cohort, CSA did not change significantly ( p = 0.175). In contrast, TAMV increased significantly from 2.40 to 4.04 cm/s (+68.3%, p < 0.001), and VFR increased from 0.77 to 1.62 cm 3 /s (+110.4%, p < 0.001). No significant sex differences were observed in pre-stretching haemodynamic parameters or in post-stretching VFR ( p > 0.05). However, post-stretching CSA was significantly higher in men (0.45 vs 0.31 cm 2 , p = 0.002), whereas post-stretching TAMV was significantly higher in women (4.31 vs 3.65 cm/s, p = 0.015). Conclusion A brief seated stretching protocol significantly improved popliteal venous return after prolonged sitting, primarily through increased blood flow velocity rather than alteration in venous calibre. This simple, equipment-free intervention may represent a practical strategy for reducing sitting-related venous stasis in sedentary settings. Further studies are required to confirm its clinical value in older and at-risk populations.