Fight Doctor – The Groin Strike

Fightland Blog

By Dr. Michael Kelly, D.O. as told to Fightland staff


Ah, the groin strike—the trauma upon which Johnny Knoxville built a career, and the scourge of every male fighter whose opponent’s inside leg kick was off the mark. Mixed martial arts may be different today than the no-holds-barred landscape in which karma channeled itself through Keith Hackney’s fists and into Joe Son’s reproductive organs, but even with its prohibition under the Unified Rules, fighters still regularly get booted in the pills. Sometimes it only elicits a furrowing of the brow without a break in the action. Sometimes a fighter needs time to recover, provoking the audience to boo the time-out before it recoils in horror at the replay. And on the most unfortunate occasions, groin strikes can end fights with a whimper and a wince. (Think Cro Cop versus Overeem, and be glad you weren’t Cro Cop.)

For all the snickers and easy jokes about getting hit in the balls, there are also genuine objects of inquiry. Why does it hurt so much more than getting kicked in the leg? Are there long-term consequences beyond pain and nausea? Are the allotted five minutes enough time to recover? And are the cups that fighters wear doing a damn thing to help? We talked to our fight doctor, Dr. Michael Kelly—a sports-medicine specialist, part-time ringside doctor, and the author of the book Fight Medicine—to explain the pain that every man fears most.

[The degree of pain from a groin strike] has to do with the afferent nerve fibers—the sensory fibers. There are a lot more sensory nerve fibers per area of tissue compared to, let’s say, the back of your hand or your shoulder. And there are so many implications with trauma to the groin area if you think about it from an evolutionary perspective: if you lose the ability to procreate, the species would cease to exist, so it’s very important at a primitive level to pass your genes on to the next generation. The extra sensation in that area evolved over time. And for most men, that’s predominantly an area of pleasure, not pain.

There are two basic structures that are primarily involved, the testicles and the penis, and the pain sensation from a blow is different in each. The sympathetic nervous system and the parasympathetic nervous system innervate different areas of the genitals, and they have different functions. The best way to put it, if you use the analogy “point and shoot,” is that the parasympathetic input is responsible for the pointing part. The shooting part—or the ejaculatory part of the reproductive function—is related to the sympathetic parts of the nervous system.

The reason why that’s significant is if you trace the nerve fibers from the parasympathetic nervous system, they predominantly come out up by your cervical spine through the vagus nerve, the phrenic nerve, etcetera, and they also come out down by the sacrum, on both sides of the lowest part of the spine. The testicles connect all the way up to the vagus nerve. It can be a sensation that goes up through the vagus nerve and give you that very nauseous feeling, whereas if you have trauma to the penis itself, you usually don’t get that sickening visceral type of pain. It’s more like, “Oh that hurts,” but it’s not the deep pain you feel on the insides of your gut, and that’s because of the different innervations. A shot to the testicles or just beneath the testicles to the perineum affects the parasympathetic nervous system, giving you that visceral type of pain.

When you get a really hard blow or pain to a visceral organ—the groin, liver, kidneys—it’s not the same situation as it would be if you had injured an extremity and you could fight through it. It gets complicated, but with any of those visceral organs, you don’t have the ability to block the ascending pain signals to the brain. Any severe blow to these organs can cause a vasovagal reaction, where you have a dilation of blood vessels and a drop in heart rate, so you actually get decreased blood flow going up to the brain. Not everybody will pass out from that, but it does immediately affect your ability to function.

I’ve anecdotally spoken to a number of fighters after they’ve taken a groin shot or a liver shot—they’re not directly connected, but it’s the same type of visceral pain that goes through the abdomen—and they say that when they first received the blow, their legs went out. It’s almost like the nerve signal just stopped instantly. They don’t pass out; they just can’t stand. It’s an interesting phenomenon that we see.

Fortunately, most of the time when someone gets a blow to the groin it doesn’t cause a severe injury. It’s predominantly pain and feeling sick, but usually it resolves within much less than five minutes. Especially if there’s a lot of sympathetic activity, like when your adrenaline is going, you tend to recover faster.

There are some exceptions. The most worrisome problem is when it results in such severe injury where the testicle ruptures and you lose the testicle, and that can affect your fertility. Sometimes it doesn’t rupture, but it can swell so grotesquely where it actually starts to impede blood flow to the testicle because it becomes so swollen and it starts cutting off the main artery. In that case, that’s usually a surgical emergency where you want to identify that and treat that surgically to decompress that testicle to save it.

The biggest problem I see [with current groin protection] is the dislodging of the cup. A direct blow straight on is usually picked up by the protector and it does its job to a certain degree, but when a blow is going lateral, or from an inferior-superior direction, it can dislodge and the protector itself can cause some trouble, where you’re actually pinching the testicular nerve artery and vein as it goes sideways or upwards. Fortunately, I haven’t seen anyone where that’s caused permanent damage. But it does raise the question of whether this is a problem we haven’t experienced yet and it may happen down the road. Who knows, there may be one guy where it does result in a catastrophic failure and permanent injury.

Cups have progressed to the point where they wrap around and cover more of the undersurface of the testicles and are fitted to go down further into the perineum. That’s a marked improvement. But are people getting the right size? It’s not something we routinely check in a pre-fight physical. I can’t avoid saying this: I think there are some guys who may be delusional, and as a result, putting themselves at risk of further injury.

The use of a steel cup is not a bad idea, but I think I would be more worried about the dislodgement of something that rigid. The plastic is pretty hard, but there’s some give, and when there’s a blow, they’re sort of flexing with the force and absorbing some of it. If you have a sideways blow and a rigid steel cup had gotten shifted to the side—picture a piece of steel smashing into the side of the testicular vein, artery, and nerve. That might cause more trouble than it was trying to protect. We can’t say for sure because nobody’s actually done an experiment with that—and I doubt you’d ever find somebody to volunteer for it.

Once, while working ringside, I saw a groin protector that had been hit so hard it dented. Not like a little dent; the thing was folded in half on itself. I saw another fight where the cup was actually split in half—that was actually pretty dramatic. It was a smaller show, and I mean he took a hard, hard shot, a straight-on kick. He went down like a ton of bricks and he really couldn’t recover. You can’t really examine in the ring, so when we got him in the back and we took a look, there was some swelling, but he was basically okay. But we looked at the cup and it was completely split in half. I was looking at it in horror almost. But fortunately, I think most guys do okay with groin injuries. We’ve been pretty lucky in that it’s not like a major recurrent injury we see all the time, so I think the cups are doing their job for the most part.

I’ll say one last thing though: I wouldn’t want to be any of the guys who have had their cups malfunction.


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