What is head-down?

Head-down refers to a position or posture where the head is below the level of the heart. This position is commonly used in medical settings such as during certain surgical procedures, in intensive care, or for managing certain conditions such as orthostatic hypotension. Head-down position can also refer to exercises or techniques in fitness or yoga where the head is lowered towards the ground, such as downward-facing dog pose. In space, astronauts are often put in a head-down position to simulate the effect of microgravity on the body. However, prolonged periods in this position can have negative health effects, such as increased pressure in the eyes and head, and decreased circulation in the legs and feet.