Vayu is a Sanskrit word meaning "wind" and apana vayu means “the air that moves away.” In the Hindu tradition, the five elements - fire, earth, water, air (wind) and ether - are represented as vayus. The apana vayu is connected with the element of earth and is the energy of the muladhara chakra. As such, it is located at the core of the pelvis.
The apana vayu and prana vayu work together by moving in opposite ways – the apana vayu eliminates and the prana vayu receives – and are considered the two most important of the five vayus. The apana vayu is the energy governing the removal of waste in the physical body, operating in the genitals, lower intestine, colon, rectum, kidneys and bladder.
Signs of an unhealthy or imbalanced apana vayu can range from laziness and dullness to confusion and indecisiveness. Balancing the vayus through practicing yoga and meditation not only promotes physical strength, but also helps the practitioner move closer to their spiritual aspirations.