Theories and MethodologiesBy F. Taillefer, J.-P. Boucher, A. S. Comtois, M. Zummo, R. Savard
The purpose of this study was to evaluate biomechanical outcomes and physiological responses during various sit-stand postures compared to sitting and standing postures. Two groups (n?=?10 per group) of women were studied (non varicosed, C0 and varicosed, C2) during twenty min periods of?6 different static posture maintenance in the sit'?stand position (base, bambach, bicycle and knee), sitting and standing in a semi random order. The following measurements during each posture were taken on the left lower limb: blood perfusion (foot), transcutaneous partial pressure of O2 and CO2 (foot), cutaneous temperature (medial malleola), foot volume (water displacement plethysmograhy), emg of the gastrocnemius muscle, and segment angulation (upper, lower limb and trunk). As well, urinary prostaglandins, VO2, heart rate, vertical heart foot distance, and perception were recorded. We observed that different postures present both biomechanical and physiological advantages and disadvantages. Biomechanically, a more pronounced anteroversion was observed during standing and some sit'?stand (bambach and knee) postures, while a posteroversion was observed during sitting and the remaining sit'?stand (base and bicycle) postures. Physiologically, the lower limb blood perfusion was similar between sitting and the sit'?stand knee posture but significantly larger when compared to standing and the remaining sit'?stand postures (base, bambach and bicycle). No significant differences were observed for lower limb oedema and prostaglandin levels between all various postures (within subjects) and both groups (between subjects). In conclusion, the smaller the vertical distance between heart/foot (hydrostatic column) the better lower limb perfusion appears to be (reduction in lower limb blood pooling). In addition, static posture maintenance for a short period of time, such as 20?min, appears insufficient to initiate the cascade of physiological events that may lead to the development of varicose veins in non varicosed individuals (C0) and does not appear to exacerbate the risk of complication in varicosed individuals (C2).