Yogic or Subtle Physiology
Backbends increase the activity of jathari agni, which helps to burn and eliminate dross from the physical and subtle bodies. They open up the front vortexes of the chakras. In bhujangasana, this is visshudi (thyroid gland), anahata (thymus), manipura (pancreas) and svadisthana (adrenals). In terms of the distribution of prana, samana vayu and vyana vayu are stimulated by backbends.