Vajrasana (vaj-RAHS-uh-nuh) and Virasana (veer-AHS-uh-nuh) strengthen the pelvic muscles, prevent hernias and relieve piles (hemorrhoids). They also relieve stiffness in the ankles, cramps in the feet, and are beneficial for people with gout, arthritic pain in the knees, pain in the heels, or calcaneal spurs.
These two poses are the only ones that can be done after meals. In fact, it is good to be in these poses for at least five minutes after meals, because they enhance the function of the digestive system.
Both Vajrasana and Virasana are meditative poses recommended by Sage Vyasa in his commentary on the Yoga Sutras of Sage Patanjali. The poses have the ability to keep the spine centered and the mind calm.
Those with any knee injuries should avoid Virasana. One can try Vajrasana instead as it involves less bending of the knees.