Leg fluid accumulation during prolonged sitting

Abstract

The accumulation of fluid in the legs due to sedentariness can be a health risk in extreme cases. Negative health impacts associated with leg fluid accumulation include leg edema and risk of blood clots. Furthermore, fluid accumulating in the legs is accompanied by fluid shift into the upper body which is also associated with health risks such as: increased blood pressure when lying down, respiratory problems in people with heart failure, and increased sleep apnea. Understanding the pattern by which fluid accumulates in the legs can aid in the development of devices for reducing leg fluid accumulation. The purpose of this study was to characterize the time course of fluid accumulation over a two-and-half-hour seated period. Non-obese participants with sleep apnea and no other co-morbidities were included in the sample as part of a larger study. Leg fluid was measured continuously using a method of bioelectrical impedance. Participants were first asked to lie supine for 30 minutes as a washout, and then sat with their legs still for two and a half hours. The main finding of this study is that the pattern of leg fluid accumulation differed in the first 45 minutes compared to the latter 105 minutes. In the first 45 minutes, fluid accumulated according to first order exponential function. In the latter period, fluid accumulated according to a linear function. The initial exponential accumulation is likely due to the large increase in capillary pressure caused by rapid blood flow into the legs due to gravity, leading to substantial filtration of blood plasma into the tissue spaces. The latter linear portion likely represents continued slow filtration of fluid out of the vasculature and into the tissue spaces. This is the first study to show that fluid accumulation in the legs is a combination of an exponential and linear functions. The linear increase identifies that there is no foreseeable point in which leg fluid stops accumulating while sitting for prolonged periods.

Compression Stockings Suppressed Reduced Muscle Blood Volume and Oxygenation Levels Induced by Persistent Sitting

“…The average optical path length actually increased in both limbs after the 3-hour sitting task with and without the compression stockings ( Table 1). The oxy-Hb, total Hb, and SO 2 levels decreased in both limbs after the 3-hour sitting task as a result of gravity effects and decreased blood flow in the lower extremities due to reduced muscle pump action, leading to the possibility of stagnation and edema [23]. Among previous studies, one report stated that the average blood flow velocity in the popliteal artery decreased significantly compared to the task value before sitting [10].…”

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

“…It is generally accepted that retention of venous blood and marked increase in capillary pressure in the lower extremities lead to substantial filtration of blood plasma into the interstitial space. Prolonged sitting causes the continuous filtration of plasma into the interstitial space and insufficient reabsorption of interstitial fluid via the venous/lymphatic system induces edema ( 27 ).…”

Breaking of Sitting Time Prevents Lower Leg Swelling—Comparison among Sit, Stand and Intermittent (Sit-to-Stand Transitions) Conditions

“…Staying in the same position (i.e., sitting/standing) for a long and uninterrupted period is associated with poorer health outcomes [ 8 , 9 ], increasing the risk for premature mortality. More specifically, sitting for a long period of time has been related to lower limb edema [ 10 , 11 ]. This condition causes discomfort and pain, and is associated with a lower quality of life [ 12 ].…”