The brain is typically more sensitive to rotational motion than linear motion because it has shear properties similar to water or gel. When different parts of the brain move relative to each other because of rotational motion, the tissues can stretch, which can cause concussions or other brain injuries.
Rotational motion is a common cause for concussions and more severe brain injury in oblique
hits to the head. The Mips system consists of a low friction layer that is mounted inside the
helmet. In a crash, the low friction layer is designed to move slightly inside the helmet to help redirect forces away from the head. This is intended to help reduce the risk of brain injury.