November 10, 2010

The New York Times の次の記事のまとめ
October 20, 2010

Summary

コンタクトスポーツである アメリカンフットボールではヘルメットの着用が同然ながら義務付けられている。
そのヘルメットには"MEETS NOCSAE STANDARD"というように規格を満たしていることを示すステッカーが貼られている。
しかし、この規格は数十年前に頭蓋骨骨折を防ぐために定められたものであり、近年問題になっている脳震盪をおこすような衝撃に対して有効であるというエビデンスはない。また、フットボール用ヘルメットはシーズンごとに reconditioning を経て何年も使いまわすのが通例。
reconditioning の作業内容、品質管理にも問題がある。
1020-spt-HELMET

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 アメリカンフットボールのヘルメット規格(NOCSAE STANDARD)

Helmets both new and used are not --- and have never been --- formally tested against the forces believed to cause concussions.
The industry, which receives no governmental or other independent oversight, requires helmets for players of all ages to withstand only the extremely high-level force that would otherwise fracture skulls.

The standard has not changed meaningfully since it was written in 1973.
The one helmet standard was written by the National Operating Committee on Standards for Athletic Equipment, or Nocsae, a volunteer consortium that includes, and is largely financed by, the helmet makers themselves.


規格制定の経緯

After more than 100 high school and college football players in the 1960s were killed by skull fractures and acute brain bleeding. 
This standard has accomplished its intent: skull fractures in football have essentially disappeared, and the three or four football-related deaths each year among players under 18 are caused by hits following a concussion that has not healed (known as second-impact syndrome) rather than by a single fatal blow.

An estimated 100,000 concussions are reported each season among high school players alone, according to Nationwide Children’s Hospital in Columbus, Ohio, but many times that figure are believed to go unreported or unrecognized.

While bicycle helmets are designed to withstand only one large impact before being replaced, football helmets can encounter potentially concussive forces hundreds of times a season.
Helmets cannot get too large or heavy, so helmet designers say they face a trade-off:
  • make helmets stiff enough to withstand high impacts and allow less violent forces to cause concussions
  • more softly cushion against concussive-type forces while allowing large impacts to crack the skull.
The helmet industry has essentially chosen the former.

Nocsae’s standard for lacrosse and hockey helmets includes tests for concussive-type forces. But because football helmets have already prevented deaths so effectively for decades, and because football’s faster and more violent environment leaves biomechanists unsure of how to prevent concussions in the sport, Nocsae has not asked helmets makers to even try.

Concussion Aware Helmets








規格を満たしているだけのヘルメット

Riddel の study

特に Riddel の Revolution モデルは前向きコホート研究により脳震盪が31%も削減したことを示せたと主張している。しかし、その数字は "notoriously inaccurate, and compared new Revolution helmets with old helmets of
unknown age and condition." と記事内では扱われている。

Riddel Press Release"Neurosurgery Study: Research shows a 31% reduction in the risk of concussion in players wearing Riddell Revolution helmets when compared to traditionally designed helmets."(2006/02/01)

University of Pittsburgh Medical Center for Sports Medicine のグループによる前向きコホート

Collins M, Lovell MR, Iverson GL, Ide T, Maroon J. Examining concussion rates and return to play in high school football players wearing newer helmet technology: a three-year prospective cohort study. Neurosurgery. 2006 Feb;58(2):275-86; discussion 275-86.

CONCLUSION: Recent sophisticated laboratory research has better elucidated injury biomechanics associated with concussion in professional football players. This data has led to changes in helmet design and new helmet technology, which appears to have beneficial effects in reducing the incidence of cerebral concussion in high school football players.

規格を変える困難さ

Nocsae receives no oversight from any independent agency. Its 16-member board features five representatives of the helmet industry, six volunteer doctors, two athletic trainers, two equipment managers and one coach.

If Nocsae were to supplement its helmet standard in an attempt to address concussions, it could open itself to lawsuits brought by players saying that their helmet did not prevent the injury.

One use of the standard often emerges after a young player sustains a head injury and sues a school district or helmet manufacturer.
the primary (and usually successful) defense is that the helmet met the Nocsae standard.

Sander Reynolds(Xenith’s vice president for product development)
“If there’s a lawsuit, they all look to Nocsae to say, ‘Hey, see, the product met the set standards.’ They’re all ultimately on the same side when it comes to liability. Nocsae exists for two reasons --- to avoid skull fractures, and to avoid liability.”


National Federation of State High School Associations(NFHS) ではヘルメットは“met the Nocsae test standard at the time of manufacture.”とだけ定められている。
※NFHS サイトには e-ラーニングの "Concussion in Sports - What You Need To Know" という無料コースも用意されている。

リコンディショニング

To the extent that 1.7 million helmets do undergo reconditioning each year, they encounter procedures and practices that industry experts described as laughable if they didn’t compromise the safety of children’s brains.

1.7 million helmets do undergo reconditioning each year
Only about 10 to 20 percent of football players of high school age or younger wear a new helmet
But data closely held by the National Athletic Equipment Reconditioners Association, Naera, indicated that about 500,000 young players this fall were wearing helmets that had not undergone this basic safety check, which encounters glaring failures of its own.


Nocsae’s sole means of quality control is to require each reconditioning facility to perform the Nocsae drop test
The test is failed by about 1 in 300 reconditioned helmets, according to Naera reports.
This largely faith-based process allows for significant errors.
※ テスト内容は the NYTimes 記事の画像にあり


Mr. Fisher of Naera and most everyone involved in the helmet industry agreed that helmets older than about 10 years present an unacceptable safety risk. Riddell and Adams both strongly recommend that their helmets be discarded after 10 years. Schutt sets no such limit.

“There’s no scientific evidence that a helmet has to be pulled after 7, 10, 12 years, that there’s some line in the sand,” Schutt’s Erb said. “There are helmets that are out there that are performing fine. Do you want your car manufacturer to tell you that your car, at the end of 10 years, you have to destroy it? That’s a decision for the user.”


10年を超えたヘルメットは安全性に問題があるものもあるとする主張に根拠はなく、逆にそう主張することで10年間メンテしなくても済むと曲解することの温床になっている。A helmet that is reconditioned properly, recertified properly and inspected properly, is suitable for returning to the field --- no matter how old. といったことを主張。

Nocsae の今後の対応

Nocsae decided earlier this month to consider moving on the matter of a concussion-related helmet standard.
the process will take at least three or four years.

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UPDATE ON 2010/12/09

The New York Times の次の記事から
"N.F.L. Invites Helmet Safety Ideas" By ALAN SCHWARZ, 2010/12/08

NFL の head, neck and spine committee がヘルメットメーカー(The National Organizing Committee on Standards for Athletic Equipment (Nocsae))、外科医、生物力学などと会合をもった。

  • 既知:Football helmets worn at all levels are held to an industry standard that addresses only the extreme forces that would otherwise fracture skulls, not the less severe impacts that are believed to cause concussions.
  • DONE:One matter that achieved some consensus, attendees said, was that football helmets worn by children should be held to different standards than those worn by N.F.L. players. 
  • TODO:science has not yet identified the conditions under which a player sustains a concussion.
  • TODO:There are scientific revolutions...New materials will come up that are stronger and lighter. The question is will it work for eliminating concussions.



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