…helmets used in youth football have historically been scaled-down “little adult” versions of varsity helmets. Therefore, scaling down varsity football helmets fails to consider youth players’ impact conditions, developing spinal musculature, maturing brain, and head-neck disparity. And thus, today’s youth helmets may have energy-absorbing features that are not optimized for these lower dose impacts.

Moreover, strategies, such as the use of semisoft energy-absorbing shell, viscoelastic padding…may have provided added protection via reduced energy transmission to the brain.

via Impact test comparisons of 20th and 21st century American football helmets – Bartsch et al J Neurosurg. Nov 4, 2011

It’s all about proper energy absorption. From a physics standpoint, Sicking said the rigid outer shell of a helmet doesn’t work well for absorbing the energy between two objects. The helmet itself needs to absorb more energy…The shell needs to be made out of a different material…What you would like to have is a helmet that flexes a little more and restores itself more slowly… The more time it takes the shell to restore its shape, the safer it becomes…Anything you can do to extend the duration of the impact motion is a win. It’s a redesign of the outer shell of the helmets that will make the biggest difference.

via “Famed engineer turns eye to football” – ESPN.com

Today’s helmets do a marvelous job of protecting against skull fracture. That’s something we almost never see anymore in our practice. And, helmets reduce the most serious inter-cranial bleeding — they’ve reduced that dramatically, by almost 80 percent. But they don’t do very much for protecting against concussion.  That’s because the most injurious acceleration the brain can get is a rotational one, where the head is spun violently. The helmets don’t do very much at all about attenuating those forces. I’m totally in favor of better helmets, but unfortunately I don’t believe that helmets are the solution in terms of concussion.

via “Dr. Robert Cantu Speaks Out About Concussions in Youth Sports” – Train ‘Em Up Academy

The solution, as suggested by former Cowboys quarterback Troy Aikman: Go old school. Until the NFL made the plastic football helmet legal in 1949, players’ headgear was made of leather — soft, relatively cushy leather, which protected, well, no one. Because brain injuries are internal, and often take years to manifest, football players usually give little thought to leading with their noggins. Were leather helmets to be implemented, however, nobody would do such a thing. Well, maybe they’d try for a game or two. Then, heads would turn bloody. Skulls would crack. Ears would bleed. And that would be that.

via CNNOPinion Jeff Pearlman March 4, 2011

The helmet has evolved so that it is heavy and protective against major injuries, and this has led to players using their heads as battering rams, often with no hesitation. When this results in a concussion, we are, at least from the vantage point of diagnosing the problem, almost fortunate – we know that the brain has been jostled and can then tend to it. But there are many other times when there may not be a concussion suspected, and the sum of these “subconcussive” blows may cause serious harm

via “This is your brain on the gridiron: Are sub-concussive hits the most dangerous of all?”- NY Daily News

…this study is the first to report on head impact exposure in youth football. Valuable insight to the head impact exposure in youth football has been presented. While youth football players impact their heads less frequently than high school and college players, and have impact distributions more heavily weighted toward low magnitude impacts; high magnitude impacts still occur. Interestingly, the majority of these high magnitude impacts occur during practice. Restructuring youth football practices may be an effective method of reducing the head impact exposure in youth football. These data are the basis of educated decisions about future changes to youth football and have applications toward determining guidelines for youth-specific helmet design.

Daniel, R.W. et al; Head Impact Exposure in Youth Football; Ann Biomed Eng. Apr 2012