Not until one afternoon when he was on his living room floor, trying to help his baby daughter learn to walk. A sudden back spasm struck him – one of many in a career plagued with lower back problems – and briefly paralyzed him on the floor.
"My daughter was around one [year old] at the time, so she didn't know what was going on," Shamrock said. "But I was like, I can't even get up to help her, so I'm not sure how much more of this I should be doing. That's about when I decided to stop."
Now the 38-year-old Shamrock is retired from MMA competition, so he doesn't have to worry about putting his body through any more abuse. But much like other MMA legends who have called it quits recently, Shamrock has no way of knowing what cost he may be forced to pay later in life for the abuse he put his body through in pursuit of athletic glory.
Not that it should come as a surprise to anyone, but the injuries fighters push through -- the ligament tears, the broken hands and noses, the concussions -- come with a price. But since MMA is still a relatively young sport, there aren't many case studies in physical longevity to tell us exactly what that price might be.
Orthopedic surgeon Dr. Johnny Benjamin, who's treated several MMA fighters over the years, said the difficulty often lies in convincing banged up fighters to consider their futures at all.
"That's the problem: the young man never wants to pay for the old man that he will inevitably become," said Benjamin. "At 20 years old, I mean, how many 20-year-olds are saving for their retirement?"
For fighters, health issues like post-traumatic arthritis in the hands and joints they've damaged over the years are likely to run rampant as the current generation of fighters grows older, said Dr. Benjamin. For those entering their forties and fifties, they could be looking at the type of total joint replacements that we normally see in people in their seventies, he added.
That's simply what happens when you put your body through daily punishment in order to make a living, said Dr. Benjamin, but it's not his main concern for MMA fighters.
"The thing that worries me most for MMA fighters is more general, and that's their lack of health care coverage going into their later years. They have adequate coverage while they're fighting for a major organization, like the UFC, but what about all the fighters who never make it to that level? Even the fighters who make it to the pinnacle, where are they going to be down the road?"
Think of it this way: if you break your arm or injure your neck while under contract to the UFC, the organization won't hesitate to get you some of the best medical treatment money can buy. But what happens when that same injury starts giving you trouble ten years later, when you're no longer on the UFC roster?
Take Jeff Curran, for instance. Once a featherweight in the WEC, the MMA veteran with more than 45 pro fights to his credit now finds himself back on the small circuit, where the health care options aren't nearly so rosy. Curran recently paid $4,000 out of his own pocket for a surgery that he needed following a fight at a small event where he made a total of $330, he said, and it's not as if there aren't other health problems for him on the horizon.
"I've had a total of seven broken ribs, from three different times," said Curran. "Four of those seven were broken more than once. I've had three surgeries to one knee. I've had a plate put in my forearm and then, eight years later, removed from my forearm. I've had fractures in my orbital. I've got no feeling on the left side of my face. I've got a completely deviated septum from being punched in the nose so much. Both feet have been broken and both hands have been broken a number of times. I have arthritis in my knees. In both shoulders I've had torn labrums and now they're developing cysts inside the joint. And that doesn't even count all the little things."
As fighters like Curran enter their forties and fifties, said Benjamin, it's hard not to wonder how they'll manage to pay for their mounting health costs.
"It's not just the injuries they'll suffer at a higher rate than they otherwise would have, but they don't have programs in place like the NFL or Major League Baseball...to protect these guys down the road," said Dr. Benjamin. "There's no health care for them. There's no pension plan for them. There's none of the safety-net features that the other major organizations have, so what are they going to do?
"Think about it, when you're 40 or 45 years old and you start having all these health problems from years and years of competition, it's kind of hard to then go out and find health insurance. Nobody wants to insure that."
It's not just the joint injuries either. While MMA may not involve the constant head trauma of boxing or football, there's no denying that taking blows to the cranium is and always will be a part of the sport.
We can come up with comfortable euphemisms for it – just imagine if instead of shouting 'He's rocked!' as a fighter staggers around from a potentially concussive blow, UFC announcer Joe Rogan said, 'He's suffered minor head trauma!' – but it doesn't change the reality of the situation.
The question is, do fighters fully appreciate the risks they're facing, and are they making an informed decision to accept them?
If you ask Strikeforce middleweight and MTV star Jason "Mayhem" Miller, the answer is, absolutely.
"Athletes know this stuff. We do," said Miller. "We're not dumb. It's like that new research that links head injuries and Lou Gehrig's disease. Well, duh, science. Thanks for telling us what athletes already know. We know what we're doing to ourselves. It's the elephant in the room. We're giving our bodies for the entertainment of the masses. I'm okay with that. I've had plenty of surgeries. I know there's a chance that I could be retarded. I know that."
According to Miller, fighters realize that some day the bill will come due for all they've done to their bodies. The only real surprise, he said, is how quickly it arrives.
"It's one of those things where, when you start out in this as a kid you look at the older guys and think, man, he's f---ed up. That's going to be me. I remember the day I got my cauliflower ear I was like, well, here I am. Then my nose got smashed and it's like, here we go. I knew this would happen. I just didn't know it would happen this quick."
MMA legend and former UFC champion Pat Miletich, who once suffered a neck injury in training that nearly severed his spine, echoed that sentiment.
"Everybody knows the risks," said Miletich. "Even somebody with one eye and half a brain recognizes the risks. But what are you willing to do for fame and fortune?"
The question is, how far do we collectively allow a fighter to go in that pursuit? At what point are organizations or regulatory bodies justified in stepping in and making decisions for him in order to protect his health?
It's something state athletic commissions do on a smaller scale with medical suspensions, but is it enough? According to Dr. Benjamin, not when it comes to head injuries and concussions, many of which may go unreported or undiagnosed in training.
"The thing that I've always said, and it's been extremely unpopular, is to limit the number of concussions they can take before they are mandated to take a break from the sport. I mean, you look at Wanderlei Silva or at Chuck Liddell recently, and you don't have to look too hard before you think that maybe they shouldn't have been fighting so long. Or a guy like Todd Duffee, who everyone thought the world of, and now he's had his lights shut off a couple of times. Maybe he needs a mandated year off from the sport to allow his brain time to heal."
And yet, to a young fighter who knows he only has so many profitable years to make enough money to see him through to old age, a year is an awful long time.
Fortunately for Shamrock, he had the financial stability to walk away from MMA once he began to feel that it was no longer worth the physical costs. Even though he might sometimes feel like a 38-year-old in a 60-year-old's body when he gets out of bed in the morning, he said, he would "100 percent do it the same" if he had to do it all over again.
It's the same for Curran, who at 33 years old now sports a litany of injuries that reads like the results of a multi-car pileup on the highway. It's not that he's never considered what price he might be paying for his MMA career, he said. It's just that he never seriously considered any other way to live.
"I remember my wife, I was just dating her at the time and I was about 20 years old and she'd say, 'I can't believe you're putting yourself through this. Do you know what you're going to be like when you're 30?' Now I'm in my thirties, and it's like, what am I going to be like when I'm 40 or 50? ...Hey, sometimes I wonder what it's going to feel like tomorrow."
'The Truth About...' is a recurring feature on MMAFighting.com that takes an in-depth look at various aspects of the sport. Check out past installments, such as 'The Truth About Losing' and 'The Truth About Choosing Your Fights.'