An evaluation of football helmets under impact conditions.

The impact attenuating characteristics of a sample of 81 football helmets used in competitive high school programs were determined using a Hodgson-Wayne State University (WSU) headform and a modified National Operating Committee on Standards for Athletic Equipment (NOCSAE) test protocol. The helmets, classified by liner type as suspension (37), padded-suspension (22), and padded (22) had been in use for 6 to 8 years. Each was subjected to two consecutive right rear boss impacts from a drop height of 1.5 m, onto a rigid anvil covered with a 45 durometer hardness rubber pad. Analogue signals from a triaxial accelerometer located at the center of gravity of the headform were analogue to digital (A/D) converted at 6060.6 Hz and processed on a Hewlett Packard 9845B minicomputer to yield a resultant acceleration-time curve from which peak acceleration (gpeak) and the Gadd Severity Index (GSI) were determined. The mean gpeak was 205 g for helmets with suspension liners, 165 g for helmets with padded-suspension liners, and 156 g for helmets with padded liners. Twenty-four suspension helmets and five padded or padded-suspension helmets had GSI values greater than 1200. Using a criterion of GSI1500, the failure rate for suspension helmets was 19% compared to 2% for padded and padded-suspension helmets combined. If the criterion chosen was GSI1200, the failure rate for suspension helmets was 65% as opposed to 11% for the padded and padded-suspension helmets combined. Suspension helmets are decidedly inferior under impact conditions to the padded and padded-suspension helmets.