structural:expansion, structural:summarization
Others

Lack of exercise is another common cause of water retention in the legs. Exercise helps the leg veins work against gravity to return blood to the heart. If blood travels too slowly and starts to pool in the leg veins, the pressure can force too much fluid out of the leg capillaries into the tissue spaces. The capillaries may break, leaving small blood marks under the skin. The veins themselves can become swollen, painful and distorted – a condition known as varicose veins. Muscle action is needed not only to keep blood flowing through the veins but also to stimulate the lymphatic system to fulfil its "overflow" function. Long-haul flights, lengthy bed-rest, immobility caused by disability and so on, are all potential causes of water retention. Even very small exercises such as rotating ankles and wiggling toes can help to reduce it.