The primary purpose of the foam lining inside football helmets is to absorb and dissipate the energy from impacts, thereby reducing the force transferred to the player's head. This foam padding cushions the head, minimizes head movement during collisions, and helps protect against brain injuries such as concussions. The foam is designed to compress under pressure and then return to its original shape, allowing the helmet to withstand multiple impacts while maintaining protection

. More specifically, the foam inside helmets is typically made from viscoelastic materials like polyurethane or nitrile foams, which absorb energy by deforming in a controlled way without permanent damage. This energy absorption reduces peak forces on the head, lowering the risk of injury. The foam also enhances comfort and fit for the player

. In summary, the foam lining's key role is impact absorption and shock attenuation to protect the player's head during collisions on the field