Effects of Prolonged Sitting with or without Elastic Garments on Limb Volume, Arterial Blood Flow, and Muscle Oxygenation.

PURPOSE The physiological response induced by acute prolonged sitting is not fully understood. Therefore, we examined the effects of 8-h constant sitting on microcirculation and associated factors in the lower extremity among healthy males. We also evaluated the protective effects of lower-pressure thigh-length elastic compression garments on these parameters. METHODS Nine healthy males (age, 22.6 ± 1.4 years; body mass index, 22.4 ± 1.8 kg·m-2) completed the 8-h constant sitting experiment. Following baseline measurements, each subject was randomized to wear a lower-pressure elastic garment on the right or left leg from the inguinal region to the ankle joint, with the non-compressed contralateral leg as a control. Circumferences of the calf and malleolus, extracellular water contents, blood flow and shear rate of the dorsal metatarsal artery, and oxygen dynamics in the gastrocnemius muscles were measured in both extremities before, during, and after 8-h constant sitting. RESULTS Compared with baseline values, 8-h constant sitting caused enlargement of circumferences (calf, 2.4 ± 0.7%; malleolus, 2.7 ± 1.4%), retention of extracellular water in lower extremity muscles (10.1 ± 1.78%), deterioration of the blood flow (61.4 ± 16.2% of baseline) and shear rate of the dorsal metatarsal artery, and decrease in oxygenated hemoglobin and total hemoglobin levels in the gastrocnemius muscle (p < 0.05, respectively). When subjects wore the lower-pressure thigh-length compression garment, a significant reduction of these effects was observed (p < 0.05, for all). CONCLUSION Prolonged sitting for 8 h induced edema, as well as deterioration of the arterial blood flow, shear rate, and microcirculation in lower limb muscles. Conversely, application of the lower-pressure elastic garment successfully prevented the pathophysiologic deterioration associated with prolonged sitting.