I just watched this compilation https://youtu.be/p4aRkLSgNGY. I've been sparring for a few months now, and even though I've never been knocked out, I can see how one would get knocked out. In this video though, the fighters are just eating the hits with their chins.

So my question is: Why, and how are they able to do that? Just take uppercuts that would send most people flying, and still be ok with it? I'm sure they're concussed like crazy after that, but how are they still up? Weak hits from their opponents? Drugs? Natural resiliency? Something that can be trained?

  • It's the strikes you don't see that knock you out, not the ones you see coming.
    – Mike P
    May 20, 2018 at 17:36
  • So if you're ready for it you can just "prepare" and take them? Like tense some muscles and resist them? May 20, 2018 at 18:56
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    I don't know the exact mechanism (hence I wrote a comment not an answer!), but as I understand it, the preparation is what 'saves' you.
    – Mike P
    May 21, 2018 at 9:27
  • Ok makes sense. May 21, 2018 at 9:28

4 Answers 4


Boxers, kickboxers, and MMA fighters train to be able to minimize the damage caused by a hit to the head. It's actually pretty hard to knock anyone out who has trained for any length of time in these arts.

One thing to realize is that you have a natural instinct to flinch whenever you see something coming towards your face. You might still get hit, but the fact that you saw it ahead of time means you began to get your hands up and your head out of the way. This diminishes the impact.

Another thing to realize is that tucking the chin can mitigate a lot of the impact force. Instead of it shocking your brain, it gets reinforced by your body and prevents the sudden recoil of the head. Boxers, kickboxers, and MMA people are taught this on day one.

And then there's conditioning. Getting hit in sparring by guys that aren't necessarily trying to knock you out but are still hitting hard will toughen you up and get you ready to take hits. Your body will adapt to it.

Conditioning also means strength and stamina. Having a strong body that doesn't get fatigued during a fight is vital. If you gas half-way into the first round, your odds of getting knocked out go up a lot. It means your defense becomes weak. You stop being able to move to avoid hits. You'll go down quickly.

There's age and previous knock-out history as well. The more you've been KO'd, the more likely you'll be KO'd. I think it's just that the body wears as you get older and have been subjected to more damage.

Having a history of being KO’d before also means you’re less likely to continue fighting. The people left in the game are, therefore, people who either have little experience or who have lots of experience. Those who stay as fighters a long time are people who don’t get KO’d easily. So it’s kind of a selection bias. These aren’t typical people. These are exceptional people.

Lastly, there's genetics. That probably counts for a lot. How your body is put together, whether or not you're able to grow muscle in all the right places, your brain's response to low/high blood pressure and adrenaline, etc. Genetics plays a role. How big? I don't think anyone knows.

Hope that helps!

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    As a caveat, there's some evidence that the techniques that fighters use to avoid getting knocked out are a strong factor behind their more long-term damage, although it's confounded by the fact that someone who doesn't get knocked out with one blow is going to be getting hit by more of them. May 21, 2018 at 11:54
  • Yeah, I think that's the main factor. The more time spent getting hit, the more long-term damage you'll accumulate, particular brain damage. So it's a double-edged sword. Yes, you're skilled at fighting, but you're also hurting yourself more and more as time goes on. Someone who's not as good a fighter might quit competing altogether, thereby saving their brain from cumulative, long-term damage. Ironic. May 21, 2018 at 14:03
  • Adding my two cents about conditioning - some boxing classes do have "resillency" training - when your partner is hitting your head, and you are standing still, "eating" it with your defence. With time, hitting becomes harder - it is somewhat like M-T leg conditioning with light strikes to the log. Apr 8, 2021 at 12:05

In the case of boxing, it's mostly "natural resiliency", combined with strong neck muscles from training. For the higher weight classes in boxing, it's a process of elimination: the boxers that get knocked out (repeatedly) don't advance and usually leave the sport, a form of "natural selection", that results in the top ranked boxers in the higher weight classes having a "natural resiliency" to getting knocked out.

One example from the past is Muhammad Ali, who was able to take punches that would KO most of the other heavyweights at the time. This doesn't mean there isn't brain damage, and most of the higher weight class boxers, especially ones with longer careers, ended up with fairly severe brain damage.


I read why you get knocked out from a punch: its because of the twisting motion that disrupts a link in the brain. The twist is in your brain stem, that is why when you get hit in the corner of your jaw, your head twist along with the brain stem and the lights go out.

I couldn't find anything on why some seem immune to being knocked out and some have a glass jaw. It probably has something to do with seeing it coming: you turn your head in a certain way, making the twist not as much. I have never been knocked out either and I crashed a 3-wheeler, landed on my head and broke my jaw. Didn't even phase me. I'm sure I can, just hasn't found the spot.

I think there has to be something physical also. Some MMA guys don't lose very often and some can't make it thru the first round and the ones with good records defiantly eat their share of punches. I have seen some eat a sucker punch and all it did was piss him off and others take the lightest hit and the lights are out.

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    If you read about this somewhere, please provide a reference so others can read it too.
    – mattm
    Sep 1, 2020 at 16:44

I think this really really relies on your neck. My dad has been hit with baseball bats, crowbars, over thousands of times punched right in the head and has never not once been knocked out. He has the biggest neck you would ever see. Also genes might also play a role in it to. Like how most explain, that liquid that keeps your brain from getting knocked out every time you move, might just be significantly more than the average person. But if you're like me and have half the family being tough fighters, remember that the other half could be dominant in your body so your neck and "brain protect liquid" might not be as good as you’d think.

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