Yoga inversions may make you think of gymnastic-like poses such as Handstand or Forearm Stand, but any pose that has you put your head below your heart is classified as an inversion. Turning yourself upside down may take a leap of faith and seem contrary to your upright nature, but the practice provides a number of health benefits. Inversions aren't for everyone, however. Check with your yoga teacher and doctor if you have a chronic condition such as high blood pressure, glaucoma or epilepsy, which are contraindicated for yoga inversions.
As gravity pulls your body down, tissues and fluids in your body pool towards the lower extremities -- resulting, potentially, in varicose veins and hemorrhoids. As you age, fat and skin sag, which physically and, perhaps emotionally, drags you down. Inversions give you temporary relief from the pull of gravity. Anatomist David Coulter, PhD explains in a Yoga Journal article that when you turn upside down, the fluid in your lower body drains better to the veins and lymph vessels, helping to clear up congestion in all parts of your body. Blood goes quickly to the heart and circulation improves, which may help your body get rid of waste products more efficiently and enhance the flow of nutrients to working cells. Fluid and blood that tends to concentrate in the lower lungs due to gravity is distributed to the upper lungs during inversions and this may enhance the health of your lung tissue, notes Pat Layton, physiology teacher for the Iyengar Yoga Institute of San Francisco's Advanced Studies Program, in the same "Yoga Journal" article.
Yoga, particularly inversions, can help enhance immunity, notes a review published in a 2008 issue of the International Journal of Yoga. Authors Sarika Arora and Jayashree Bhattacharjee, biochemists in New Delhi, India note that a pose like Downward Facing Dog improves the flow of fluid in the sinuses and can flush mucus from the lungs. Forward bends may have similar benefits. Inversions may also enhance functioning of your lymphatic system, which plays a role in immune response. Legs Up the Wall pose, called Viparita Karani, is a simple example of a lymph-stimulating inversion.
Inversions also enable the heart to rest from the work of constantly pumping blood. When you turn upside down, pressure in your body changes and blood rushes to your head. Receptors in the brain that regulate blood flow sense the increase and signal the heart rate to lower and blood pressure to reduce. It is unclear as to whether inversions lower blood pressure for any significant amount of time after doing such poses, however. Because inversions do affect blood pressure in a way that is not completely understood, they are considered a contraindication for people with high blood pressure.
Research shows that a yoga practice that includes inversions can boost your mood and improve the symptoms of depression. A study that was conducted by researchers at University of California, Los Angeles and published in a 2004 issue of "Alternative Therapies in Health and Medicine" followed 28 participants who showed signs of mild depression and participated in a one-hour yoga practice that including inversions twice weekly for five weeks. After the course of the study, those participating in yoga regularly reported significantly decreased symptoms of depression. The yoga practice also correlated with a normalization of the stress hormone called cortisol.