The cheetah is equipped with an ultra-flexible spine that allows it to be the fastest land animal. This is because the spine is capable of doubling over on itself, much like a coiled spring, and propels the cheetah forward. The range of human motion only allows the spine to bend in one direction, the cheetah's however is capable of bending in two, creating a visible "s" shaped posture when running. When fully coiled, the paws on its hind legs actually end up in front of the cheetah's head. This increaseses the length of its stride, up to 4 times its body length, and increases the compressionnal aspect of its spine.