HELMET NEWS: SEPTEMBER 2004
THE FOOTBALL HELMET, PART ONE
By Dr. Ken
Those of us interested in the football helmet are immediately attracted to its design, colors, logos, striping, facemasks, and any individual or unique cosmetic application that distinguishes it from other helmets. The true purpose of the football helmet however is to protect the player and reduce the probability, frequency, and severity of head injury that results from impact. We know that a blow to the head or a rapid acceleration/deceleration action can produce injury as noted in previous HELMET NEWS segments. The helmet is supposed to reduce this type of injury although there is no helmet that has yet to offer the promise of eliminating these same injuries. By encasing the head in some combination of plastic, foam, and air padding, the helmet helps to cushion the head against impact. Unfortunately, the ultimate protective headgear cannot yet be produced as there are compromises to be made. The helmet has to be affordable, thus, there are constraints in design and materials. In order to minimize the weight and mass of the helmet, there are design and material constraints. If the player won’t wear the helmet, or wear it properly in order to take advantage of its design because it is too uncomfortable, it won’t provide the appropriate protection. Impaired visibility, improper ventilation, and other factors all make helmet design a difficult and time-consuming process.
The helmet shell is hard and its shape and materials are designed to distribute the impact force over a large area while preventing penetration. The shape is such that impact is “glanced off” of the shell as quickly a possible. Recall please that the longer the impact, the higher the probability of damage to the head or neck. Some of the new helmets have a distinctively different shape than the previous helmet designs in an attempt to forge a lighter weight helmet. Maintaining a lighter weight while enhancing the thickness at specific strategic contact points helps to give these new helmets their unique configuration. The shape, ridges, and ventilation holes do not create a change in shape that would make the helmet more dangerous due to creating a higher time of impact or reduced ability to “glance off” a direct blow to the head.
Energy absorption occurs by the inner liner of the helmet. Through the years, this inner lining has evolved from a variety of foams to suspension webbing to combinations of webbing and cells of water, alcohol, or air, to modern “systems” of air and foam modules. Net energy absorption will determine the effectiveness of the lining and like the shell, the materials use are often a result of compromise between what is possible and what is both affordable and comfortable enough to achieve compliance of use. All of the desired properties of both the shell and lining must be fitted in such a way that the primary function of maximal protection is achieved. This is often a daunting task and differences in perspective and philosophy often explain why there is a variety in helmet shape and materials used from one manufacturer to another. Of course, in 2004 as this is written, the choices are somewhat limited with only three manufacturers producing protective football helmets in the United States. Past segments of HELMET NEWS have given insight regarding the legal maneuverings that have resulted in this unfortunate state of affairs.
All helmets on today’s market must satisfy minimal performance criteria. If the helmet’s protective capacity falls below this minimal standard, it will not matter how optimal other aspects of the helmets construction or materials utilized are. Performance is the key to helmet safety and acceptability. The “minimal standard” is by definition, a compromise, an agreed upon cut-off point determined by experts in the field of human biomechanics, engineering, materials design, and medical personnel. In short, the standards are arbitrary but based upon certain scientific and medical knowledge and experience. The performance capability standards can be seen as what has been taken to be acceptable by the community that purports to oversee the safety of the product and the participants at the junior high school through professional levels of football.
More details to follow next month.