Fresh off a 3 round drubbing at the hands of resurgent heavyweight wunderkind, Stipe Miocic at UFC 161 all anyone's been able to talk about is the incredible chin of one "big country" Nelson. After all, he set the record for most power punches absorbed without being knocked out at heavyweight. Leave it to one of my favorite and most magnificent combat sport themed sites to explore the science behind everybody's favorite hillbilly Santa's "iron chin" with commentary from sports-medicine specialist Dr. Micheal Kelly. (Link to original article)
So what gives one a "granite chin"?
Dr. Michael Kelly: There are a few things that might account for someone having what we might call a "granite chin." The first thing is really strong neck muscles. You can absorb a great deal of the impact. The second is the actual shape of the jaw. Some people are more vulnerable depending on the shape of their jaw. And then there's how many previous knockouts a fighter has had. If they’ve had a lot of knockouts they become more vulnerable with each fight.
Interesting, he mentions guys who've been knocked out before being more "vulnerable with each fight". Well, Roy has been knocked out before and has taken a ton of damage in fights and presumably in the gym as well so what gives Doc?
there are some people who are genetically gifted in the way their body is built, the strength, the shape of the skull, the density of the brain, let’s say the number of ion channels they have per neuron, or the mitochondria density in the cell, they can absorb more punishment or reduce the effect of a blow on their brain better than other people. There are a lot of variables, but some people are just more genetically gifted in that area. In a lot of sports there’s people who, despite what you may think, there’s just something they have, that they were born with, that you can’t teach or train. But it will all catch up to him eventually. No matter who you are, you can only take so many blows to the head before it starts to have its effects. So though someone like Roy Nelson has a gift for not getting knocked out, I think eventually everybody can be knocked out. Age, multiple trauma, multiple variables will build up.
knowledge bombs galore:
Nelson might have extremely strong neck muscles. Strong neck muscles can cut down on the rotational force of a hit. A lot of what determines whether someone gets knocked out has to do with where the force is transmitted into the brain. Where there’s a very strong rotational force on the skull—shots that come from the side, like hook punches, rather than straight linear shots--most of that vector force gets transmitted down into the brainstem area into what’s called the reticular activating system and that’s what’s responsible for being awake. So when you go to sleep, certain cells on the reticular activating system will get stimulated and go to sleep. When you wake up, certain cells will get stimulated and you wake up. It’s actually multiple tracks in the lower brain stem. Together their called the reticular activating system. And you have a layer of fluid surrounding the brain on the upper part. Again, with a very strong rotational force on the skull, say from a hook punch to the side of the jaw, what happens is there’s motion on the top of the skull because the brain is sort of floating, but as you get down to the base where it’s anchored, it’s tighter. It doesn’t have as much give. So that’s when you get that kinking in that part of the brain and that causes loss of consciousness.
If you have, say, a concussive brain injury, the brain, it’s very soft, it’s like a gelatinous material, and when you have sudden dynamic vectors in multiple directions the brain can change shape on a microscopic level for a split second and that causes disregulation of the ion channels and the neurons. And you wind up getting an alteration in the normal balance of sodium that’s passing inside and outside the cell. And that’s what causes the neurons to become dysfunctional.
So as you’re hitting on the side and you rotate the head, it’s a little bit easier to transmit that force to rotate the head. Whereas, when you’re hitting direct on at the button of the chin, sometimes it’s a little harder with a very strong mandible. That's where the shape of the jaw comes in. It’s all a matter of shape and size. It has to do with the ability to transmit the force to the base of the skull. That’s why people are always talking about fighters getting hit "on the button."
I suggest you drop whatever you're doing and go read the whole article NOW. It's chock full of goodness.