In the early 1980s, NASA conducted a series of experiments to determine the exact position the human body assumes when suspended in zero-gravity conditions. This position is the body’s natural resting position, and it affords exceptional relief from lower back stress while also placing your heart on an equal plane with your body mass, thereby minimizing the effort required to pump blood throughout your body. Zero Gravity chairs are designed to recline to this natural position for maximum comfort and relaxation..