Introduced over two decades ago, zero gravity recliners offer a unique resting experience. Like many of the conveniences and gadgetry we enjoy today, the idea for a zero gravity recliner is said to have originated as part of the space program. As part of the NASA biomechanical systems program, the zero gravity recliner has its roots in astronaut safety and comfort.
During the blastoff phase of any manned space flight, astronauts are exposed to tremendous gravitational forces. In order to help astronauts withstand the intense G forces, NASA has developed different seat configurations and padding materials. Visco elastic memory foam was part of this development process, though memory foam was never used as part of a space craft. In spite of being a failure as a component of manned space flight, memory foam is now used in all types of applications, including upholstered furniture and mattresses.
One of the many physical challenges faced by astronauts is compression of the discs that separate the vertebrae in the spine. Even for us earthlings, normal gravitational pressure of just over fourteen pounds per square inch can cause disc compression. While breaking free from the bonds of Earths gravity and at speeds of thousands of miles per hour, astronauts can find themselves exposed to over ten times the normal gravitational pressure found on Earth. The force of Earth gravity is so strong that a spacecraft would need to be moving at over twenty five thousand miles per hour, referred to as the escape velocity.
Zero gravity recliners tout several important benefits to these unique furniture pieces. The benefit most often mentioned is the effect on the spine. Sitting in a fully reclined position with the feet higher than the head can relieve pressure on the spine. Do not think of being fully reclined as laying flat in the recliner. The basic concept behind the zero gravity recliner is to place to body in a position such that compression forces on the spine are reduced to as near zero as possible. Achieving this state requires that the knees and hips be held at ninety degree angles.
With the feet raised above the heart, blood circulation to the legs changes. In a standing position, the heart must work harder in order to pump blood back to the heart from the legs. The heart needs to overcome the forces of gravity which naturally causes blood in the legs to pool. This is the same condition experienced by astronauts and pilots during periods of exposure to high G forces. So with the legs elevated, the heart does not have to work as hard.
A host of benefits are attributed to the use of zero gravity recliners. Along with relieving pressure on the spine proponents tout the ability of the chair to relieve muscle strain, increase lung capacity, reduce pressure on the heart and even raise blood oxygen levels.