Effect of continuous rotary seat pan movements on physiological oedema of the lower extremities during prolonged sitting

Objective: To assess the time-related response of swelling in the lower ext remities during static supported sitting compared with sitting in an experi mental chair which uses rotary continuous passive motion (RCPM) of the seat pan. Background: The effects of dynamic rotary stimuli on the spine have been te sted in previous studies by the authors. Relief of chronic pain was demonst rated, in patients suffering non-specific low back pain. Laboratory tests s howed an increase in body height as a result of rotation in the horizontal plane of the seal pan (RCPM), versus a decrease of body height without this stimulation. Stranden investigated the influence of a dynamic sitting patt ern of office chairs (Hag Credo 3500, Hag a.s.a. Oslo, Norway) with free-fl oating tilt mechanism, and found a beneficial effect on the transcapillary fluid balance in healthy control subjects. Method: Ten healthy subjects were measured in two conditions, with and with out dynamic stimulation (RCPM) of the seat pan, in 3 h sitting sessions, on successive days. The volume of the lower legs was measured four times, at 1 h intervals, by means of water displacement volumetry (WDV). Results: Significant differences (0.014<p<0.129)in lower leg swelling were found between the static and the dynamic situation. Female subjects showed an increased response in time-related leg swelling and the age of subjects also influenced the results. Conclusion: Dynamic stimulation during sitting has an oedema reducing effec t on the lower extremities.