Effect of sitting in ergonomic chairs on lower limb venous blood flow

The objective of the research was to assess the effect on lower limb venous blood flow of sitting in two ergonomic chairs. In a cross-over design 12 healthy subjects had popliteal vein blood flow measured by Doppler ultrasound in different sitting positions, in the Aeron and airCentric chairs. Measurements were made lying prone, sitting with the leg flexed 90° and sitting with the leg flexed 120° in one chair, followed by the same measurements in the second chair, the order determined randomly. The primary outcome measure was popliteal vein peak systolic velocity. Simple paired t-tests and a mixed linear model were used to compare blood flow between chairs and different sitting positions. For the Aeron chair, the prone to 90° position resulted in a reduction in peak systolic velocity from 27.8 to 3.5cm/s, adjusted difference 21.0 (95% CI 17.3 to 24.8), and for the airCentric chair from 21.4 to 3.7cm/s, adjusted difference 21.2 (95% CI 17.4 to 24.9). There was no statistically significant difference in peak systolic velocity between the two chairs, in the two sitting positions. There was a marked reduction in popliteal vein blood flow with sitting, but no significant difference in effect between the two ergonomic chairs.