Sitting for long periods. Sitting in one position for prolonged periods without moving restricts normal circulation of fluids in the body. The fluids flow down to the feet due to gravity and rest around the ankles. With restricted mobility to make way for fluid to be pumped to the rest of the body, ankles will swell. Doctors recommend moving around at least every one or two hours after continuous sitting. Strike your feet up and down to allow fluids to move around your body. Exercises also help immensely in releasing the intensity in already swollen ankles emanating from prolonged inactivity.