[unclebucknasty]

The problem is that helmets--including the designs you describe-- are designed to protect the skull and not the brain.

The brain suffers damage from slamming against the inside of the skull due to inertia changes during collisions that are inherent to the sport.

There is literally no way to protect the brain as the sport is played today.

[wbracken]

My understanding is the brain slams against the inside of the skull due to stopping fast. Wouldn't a crumple zone (again for lack of better term) allow for a slower transition and thus less rattling around in the skull?

[unclebucknasty]

>the brain slams against the inside of the skull due to stopping fast

Yes, that's the inertia change I referenced.

A crumple zone is unlikely to mitigate the problem in any meaningful way. The problem is that in a hard collision, the head still stops in an instant, but the brain continues to travel at the same rate of speed until it slams into the skull. Effectively slowing the distance over which the head comes to a stop by a few millimeters or so won't meaningfully offset that impact. The brain is still traveling too fast.

The kind of design you're referencing works in vehicles because its purpose is to dissipate the energy of the collision around the zones instead of through the vehicle. But, the goal here is to avoid damaging the vehicle so extensively that the damage intrudes upon the cabin (and its occupant).

However, the vehicle's deceleration itself is not altered in any meaningful way by crumple zones. So, this system really only works if the driver is restrained (e.g. by a seat-belt). Otherwise, the driver would still bear the force of the sudden deceleration when she collided with whatever was on the other side of the empty space in front of her.

Similarly, if the brain could be restrained in its skull, then helmets might have at least some value in protecting it.