To cleanse and prepare the physical body and energy bodies, which also removes any blocks or accumulation of used up energy in any part of the body, especially at the various joints. We need to exercise after the meditation in order to assimilate the energy we receive during the meditation. This also helps to cleanse and strengthen the physical body and release excess energy. Beyond a point the physical body cannot absorb more energy and the physical exercise removes this excess. When there is excess energy the physical body feels lethargic. So exercise before and after meditation is very important.
Watch this video to learn the exercise and twin heart meditation procedure.