What Korean medicine calls the retention of water-dampness can be explained in modern medicine primarily by venous insufficiency or a lymphatic circulation disorder. Our body constantly circulates two vital body fluids—blood and lymph—to remove waste products and supply nutrients. In particular, peripheral parts of the body located far from the heart, such as the legs and arms, face the significant challenge of returning blood back to the heart against gravity.
Standing or sitting all day places continuous strain on the valves of the veins in the lower body. Valves prevent the reflux of blood, but staying in the same posture for prolonged periods can weaken these valves or degrade their function, allowing blood to pool downward. As intravenous pressure rises in this way, capillary permeability increases, causing fluid from the blood to leak excessively into the spaces between tissues outside the blood vessels—namely, into the interstitial fluid. This is one of the main causes of the swelling we experience.
In addition, our body has a lymphatic circulation system that is just as important as venous circulation. Because lymphatic vessels do not possess an intrinsic pumping mechanism like the heart, they rely primarily on the pressure changes generated when our muscles move to transport lymph. The calf muscles in particular play such a crucial role in pushing lower-body venous blood and lymph up toward the heart that they are called the second heart. When you sit or stand still for long periods, this skeletal-muscle pump cannot operate properly, leading to reduced lymphatic circulation and ultimately causing interstitial fluid to accumulate, worsening edema.
If this state persists chronically, it can progress beyond simple swelling to dermatitis, hyperpigmentation, or, in severe cases, more serious conditions such as varicose veins or lymphedema. Rather than brushing it off as mere fatigue, one must take it as a warning sign from the body and manage it actively. From an endocrinology perspective, imbalances in hormones such as antidiuretic hormone (ADH) or aldosterone can also affect fluid metabolism, but in the case of occupational edema, the most direct causes remain mechanical pressure changes and impaired circulation within the blood vessels and lymphatic system.
