Effect of Footrest Angle on Decrement of Leg Swelling while Sitting

Abstract

Sitting in the comfort of chairs is an important factor of daily life, but leg swelling results in languor of lower legs and decreases sitting comfort. Many studies have examined the mechanism of increased leg swelling; however, few have investigated the mechanism of decrease leg swelling. We studied the effect of the footrest angle on decreases in leg swelling by measuring leg swelling with bioelectrical impedance method (BI method) and blood flow with near-infrared spectroscopy (NIRS). We performed the sitting experiment with six volunteers. It comprised three parts; (1) lying supine for 20 minutes to alleviate leg swelling, (2) sitting on a high stool for 30 minutes to increase leg swelling, (3) sitting on a trial chair with a footrest for 30 minutes to decrease leg swelling in order to research the differences among three footrest angles (0°, 15°, and 30°). By the results of the BI method, leg swelling increased by sitting on the high stool and decreased by sitting on the trial chair with a 30° footrest. By the results of NIRS, the quantity of deoxygenated hemoglobin (deOXY-Hb) increased by sitting on the high stool and the quantity of oxygenated hemoglobin (OXY-Hb) increased by sitting on the trial chair. In comparison of leg swelling and blood flow, it is considered that increases in deOXY-Hb influences gains in leg swelling, and increases in OXY-Hb influences reductions in leg swelling.