Inversions like Shoulderstand (Salamba Sarvangasana) are powerful because, as earthbound creatures, we are so strongly affected by the long-term impact of gravity. Over the years our bodies begin to, well, sag. This decline is clearly visible in our skin, but there are much more important, unseen consequences to gravity's relentless drag. After years of combating gravity, all the organs, especially the heart and the rest of the circulatory system, grow sluggish, which results in less nourishment to our cells and leaves us vulnerable to heart disease, fatty deposits in the blood vessels, varicose veins, and other effects of aging.
Though the effects of gravity are inevitable, we can do a great deal to counteract their impact. Like the original yogis, we can cleverly beat gravity at its own game by turning the body upside down. This simple action benefits the whole body. No wonder the early yoga masters stressed the importance of inversions and said that Headstand and Shoulderstand could conquer old age!