(Photo via CagedInsider.com)
Ed. note: Reed “The Fight Scientist” Kuhn is a Washington D.C.-based strategy consultant whose pioneering work in MMA stats analysis earned him a position as Strategic Advisor for Alchemist Management, as well as contributing gigs for the UFC, Sherdog, and Fight! Magazine. Using the information available to him as a research fellow with FightMetric, Reed examines historical trends and data to uncover new ways of looking at the sport — and predict what’s most likely to happen in a given matchup. In the coming weeks, Reed will begin providing exclusive columns and analysis to CagePotato.com. The following was originally published on his site, FightNomics. For further reading, check out “Small Fish, Bigger Pond: The UFC/WEC Merger’s Hidden Secret” and “Diamond in the Rough: Is Nate Diaz Built for a UFC Championship?” Follow Fightnomics on Twitter and Facebook.
At UFC 129 Randy Couture entered the Octagon for the last time to the cheers of over 55,000 fans in Toronto’s Rogers Centre, a massive venue normally reserved for major league baseball and Canadian football games. From a dimmed broadcast platform set up in the cheap sets, I watched alongside the cast and crew of the one-time, live pre-show experiment known as “UFC Central.” As Lyoto Machida lined up across the cage, I pointed to my analysis of the matchup, noting specifically that Machida’s evasiveness and striking ability was the key here, as was Couture’s age. Randy Couture was 47 years old and a veteran at grinding out victories. But his only hope was to neutralize Machida’s laser-like strikes via clinching and dirty boxing, possibly even ground and pound. And that wasn’t in the cards. Even from our distant vantage point, we all knew it.
Analysis of Machida showed extremely accurate striking and similarly excellent striking defense. His takedown defense was also strong, a result if his uncanny ability to maintain distance, which would eliminate any advantage a wrestler might have over him. Couture on the other hand, was a decent striker, but allowed his opponents to land their own strikes with better than average success, indicating poor striking defense. His wrestling acumen led to a good shooting takedown success rate, though surprisingly little success from the clinch. The fight’s outcome was right there in front of us on the paper. At -325, Machida was a strong but not overwhelming favorite, and yet that betting line failed to capture how much of an advantage he really had. The “Dragon” was 15 years younger than the “Natural,” a spread that generally leads to an 80% win rate for the younger fighter. On top of that, it was clear that he was going to keep his distance, meaning he could send his strikes through Couture’s loose defense at will.
As the fight began, Kenny Florian and Stephan Bonnar watched with slight grimaces while Couture pressed forward and tried desperately to get a hold of the elusive Machida. During these scrambles Machida landed punches out of nowhere with his typical blazing speed and accuracy. When the first round ended, it was almost a relief that Couture was still standing – a small victory for Father Time. But that relief was short lived, and the now famous crane kick that ended the illustrious MMA career of Randy Couture connected with his chin barely a minute into the second round. Couture’s head snapped with the impact of the surprise kick, and his body immediately crumpled to the mat before the kick was even retracted. Moments after recovering, as Randy stood flashing his Hollywood grin and confirming the retirement we were all expecting, one of his teeth fell out in his hand.
From the broadcast booth, the excitement from the amazing knockout finish was tempered by the respectful sobriety of witnessing a legend in the act of letting go of his fighting career. “It’s time” many said, “he had a great career, but it’s time.” And they were right on both accounts. No one expected another return to the cage for the Natural. He was making a wise decision to retire, one that some other fighters have been unable to make even remotely as gracefully. But what was the price of that decision?
The Aging Brain
Despite the age-defying wonder that is Randy Couture’s athleticism, why did we all know it was time for him to stop fighting? If a fighter is still physically fit late in life, haven’t they also gained years of critical experience that might allow them to remain competitive, even if they’ve lost a step? True, experience is valuable in any vocation, even fighting in a cage. But in contact sports, and especially combat sports, there’s also the looming shadow of brain injury that complicates an athlete’s ambitions.
The effects of dementia are so common among professional boxers the medical community even refers to “dementia pugilistica,” (named from the Latin root pugil, meaning boxer/fighter) while common slang includes the phrase “punch-drunk” to describe the slurring of speech and erratic behavior associated with taking too many punches over the years. And this condition is just one of many related neurological conditions associated with deteriorating cognitive and intellectual abilities. When it comes to seeing fighters get knocked out, friends, family, and fans alike would be appalled if they realized their cheers fueled a fighter to push their risk of dementia by fighting past the limits of their personal safety. And yet at least in the boxing world, there’s all too many instances of just this tragedy occurring.
That repeated concussions, and even sub-concussive events can lead to long-term neurological problems is not in question. What is in question in assessing MMA performance is whether or not knockouts lead to an increased likelihood of later knockouts. Can a fighter “lose his chin” so to speak? Can a bad knockout make a fighter even more susceptible to future knockouts? I would be speculating without medical evidence if I said the answer was yes. I haven’t run that analysis on individual UFC fighters. Partly because I’m afraid of the answer, and partly because what’s potentially more important is the effect of strikes received during training, which occur with much greater frequency than sanctioned fights. And more than anything, the age variable would need to be controlled. It’s a messy problem, and though I have the research plan to test it, I’m saving it for later. So for now I’ll take a big step back and keep things simple.
Let’s set up a relevant piece of analysis with a simple question. Does age change the way fighters perform? I’ve already covered what I call the “Youth Advantage” in MMA in a separate post and demonstrated that the younger a fighter is than his opponent, the more likely he is to win. Certain, basic physical traits do decline with age, as does our ability to recover from injury, or just from strenuous training. These are a few likely drivers of the Youth Advantage. So older fighters are at a disadvantage. But how? How is it, specifically, that the Youth Advantage takes effect inside the Octagon?
The analysis here examines all UFC fights from 2006-2011, excluding the rare disqualifications, no contests or overturned fights. I am showing how fights end by the age of the fighter; first winners on the left, then losing fighters on the right. The red area is fights ending by strikes, the blue is submissions, and the gray is decisions.
Age doesn’t have much of an impact on how fighters win (left graph), but there is a clear trend in how they lose (right graph). The increased likelihood of knockout loss in older fighters is clear on the right graph, seen by the growing red (T)KO/stoppage area that rises as age goes up. As fighters get older, there’s a steady increase in the rate at which they lose by strikes. Fighters that are 36-38 year old get knocked out at nearly twice the rate of fighters who are only 22-23. That’s a huge difference.
What’s also interesting is that older fighters are less likely to lose by submission than when they were younger. Here, finally, is the advantage of experience – submission defense keeps improving with age and training. Defending submissions isn’t necessarily a matter of strength, but of skill. The best jiu-jitsu practitioners make it look far too easy and may not even break a sweat while their opponents exhaust themselves looking for an opening. The data can be interpreted conversely too: while younger fighters are less likely to lose by strikes, they are more than twice as likely to get submitted as older fighters. Chalk one up for the old guys.
Because finish rates and methods are particular to each weight class (see Fightnomics: Size Matters), I’ve isolated a single division and aggregated the results by logical age categories to illustrate the trend. Here’s how finish rates evolve with age for UFC Middleweights:
It’s interesting that TKO losses fall as fighters hit their peak performance zone in the late 20’s, then climb rapidly throughout the 30’s. This might mean there’s a rookie disadvantage in the Octagon. It’s also interesting that submissions losses fall consistently throughout the age range. Again, that’s fighter experience adding value in the form of improved submission defense over time. But the steepest pattern is the graph is still the rising risk of (T)KO with age.
How It Happens
To figure out if there’s a better explanation of the trend, I’ve dug a little deeper on striking metrics and performance with age. Because older fighters tend to lose by strikes, perhaps there’s a cause due to the way they fight that leads to those outcomes.
Let’s consider three potential causes for the rise in knockout losses with age:
#1. Older fighters are worse strikers, and tend to lose striking exchanges
#2. Older fighters can’t keep pace with younger fighters, and so absorb more strikes
#3. Older fighter absorb the same amount of strikes, but those strikes do more damage to them
To test Hypotheses #1 and #2, I’ve shown standup head striking accuracy for jabs and power strikes, and also the total striking attempts per minute, all by age of the fighter.
There’s actually a slight rise in striking accuracy with age, and a negligible decline in striking pace. Not much of a difference. The slight rise in accuracy could be attributed to increased experience, or even the selection effect that more skilled fighters will last longer in the UFC, and therefore older fighters may be better in skill metrics. But maybe it’s their defense that declines with age, so let’s look at the same metrics based on the Opponent’s age.
The only noticeable trend here is that jab accuracy goes up with opponent age. This makes sense, because reaction time deteriorates with age, and jabs are generally shorter, quicker strikes. Thus, thus older fighters have more trouble defending jabs. But these jabs aren’t knockout blows, and older fighters maintain the same power head striking defense as younger fighters. Hypothesis #1 doesn’t look good.
We also see it’s not necessarily the volume of the strikes either, since striking volume didn’t change much with age, or by opponent’s age. There’s a slight difference in the later years, but it’s less than 10% of the total. Older fighters aren’t getting knocked out because they can’t keep pace with their opponents and are getting overwhelmed. In this very quick look we don’t see a strong case for hypothesis #2.
And that leaves us hypothesis #3.
There was a riddle posed by a cartoon owl in commercials back in the day: How many licks does it take to get to the center of a blowpop? Let’s rephrase: how many strikes to the head does it take to knock someone down? The question is a tricky one. Really it only takes one if you land it right, unless the opponent is taking a dive. But in the UFC, we can analyze how many power strikes to the head are landed divided by how many knockdowns are caused, and then vary it by the age of the fighter receiving these blows. This should answer the our question as to “how” older fighters are losing more by strikes.
Though the data here is more volatile, the basic trend is clear that it takes fewer and fewer head strikes to knock down older fighters. When it comes to standup striking, it takes half as many landed strikes to knock down a fighter approaching 40, than it did when he was in his early 20?s. This could be one of two basic effects, or a combination of both, depending on our understanding of how knockdowns occur. It could mean the likelihood of a flash knockout, or otherwise consciousness-altering concussion, is higher the older the fighter is. Or it could mean that cumulative strikes do more damage in older fighters, so they can’t keep standing as long. Either way it doesn’t really matter since the data shows clear patterns. Hypothesis #3, therefore, looks compelling: You don’t have to throw strikes at a higher pace, or land them with higher accuracy; each blow is more likely to knock down an older fighter.
It’s the Brain, Stupid
One reason knockout rates may be increasing with age is that the brains of older fighters are less resistant to trauma. Cumulative damage as well as basic physiologic changes with age lead to decreasing resiliency of the brain. Specifically, our brains atrophy over time, and the space between the critical organ and the skull increases slightly. Despite our brains floating in cerebrospinal fluid that essentially acts as a shock absorber within our heads, this protective system isn’t enough to prevent trauma in the case of a rapid acceleration (e.g., when a punch lands). As we age, the space where the brain might bounce off the skull increases, meaning the impact is harder and more damaging when the head moves suddenly than when our brains were younger, slightly bigger, and better cushioned.
This additional room for brain bouncing increases another more serious risk: “diffuse axonal injury.” Imagine that the neurons of your brain are the fibers that hold your memories and intellect together. Squishy brain matter evolved to be resilient and stretchy, much like our imaginations, but there are limits. The more violent a brain injury, the greater the risk of tearing these critical fibers that are the conduits of thoughts and sensations within the brain, the infrastructure of your Self. With a larger space at the perimeter of our skulls, the potential for this type of injury goes up as the brain gets compresses and stretched to a greater degree on impact. The tearing of these axons can occur over a wider volume of brain matter and is a serious injury very different from focused bruise, and one we don’t not yet know how to heal.
As kids, our more resilient brains protect us from our wildly active and often injurious lifestyles. But as we age, our ability to withstand trauma declines, as does our willingness to put our heads into risky activities (at least for most people not competing in professional sports). Whether it’s the accumulation of repeated concussions, or the general atrophy and resulting decline in brain resilience with age, there is an increase in KO/TKO rates as fighters get older. Period. And one possible reason is that repeated concussions decrease a person’s resiliency against future concussions – though that will require more research to confirm. An older fighter no longer has to get hit “on the button” to knock him down, as any significant blow to the head will wobble them. Or it could mean that the normal resiliency to a few head strikes before reaching a tipping point before a knockdown (or fall down) degrades with age, for all the same physical and physiological reasons. Hence, older fighters still perform at high levels, they just can’t take a punch like they used to.
After a concussion, blood on the surface of the brain isn’t fully cleared away, and a rusty colored patch may remain permanently. In autopsies a colorful map of a lifetime’s worth of brain traumas might allow researchers to better understand the cumulative effects of these injuries. A critical issue in MMA will be understanding the frequency of injuries in training vs. competition, and also how to prevent long-term damage once an injury does occur.
For some older fighters their offensive skills will keep them competitive, and even in trouble their submission defense will continue to get better. But when it comes to striking defense, a significant age differential means it’s no longer a fair fight.
What Have We Learned?
In the Youth vs. Experience battle, youth wins if it’s a striking matchup. There’s a variety of complex potential drivers of this trend, but at least the pattern is plain enough. And going deeper into the data reveals the differences in how older fighters lose. Specifically, losses by strikes rise with age, while risk of submission falls. While this information may help in forecasting outcomes from the Tale of the Tape, it also adds more fuel to the burning need for more medical research into brain injuries from sports, and how best to mitigate the risks associated with them. This isn’t to say that we, as competitive and athletic animals, should never take risks. It’s just that we should fully understand the risks we face in order to make the best decisions.
Sports, even combat sports like MMA, will continue to be a cultural backbone to our modern lives. The passion we feel in competition, and even as spectators, is a defining human characteristic, and our lives would undoubtedly feel incomplete without competitive outlets. While sobering research results such as these may lead to that sinking feeling of weakness at the human condition, we should remind ourselves of the amazing capabilities of our innate athleticism. A gentle reminder of our mortality contrasts sharply with the sometimes surreal invincibility of MMA champions, but it’s a healthy exercise to look for balance, even amid extremes. MMA fighters are quickly becoming recognized as some of the world’s greatest athletes, and that is something the sports should embrace, celebrate, but also help preserve.
This isn’t the end of the Youth Advantage question though, and there are plenty of other angles to pursue. For example, there may also be a selection effect at work here. Exciting (i.e. aggressive) fighters may earn the right to stick around the UFC through more losses than other more conservative fighters, and hence older fighters may be filtered for a disposition to risky knockouts by their innate fighting style. Chuck Liddell is a classic case, once stating that he would never change his style of fighting to make up for how prone he was to knockouts at the end of his career. But given the steep increase in knockout losses for older fighters, and the danger that further traumas pose to their long-term mental health, putting your brain at risk is a truly dangerous prospect as fighters approach their 40’s.
While their guts, hearts and egos may believe they still have a few fights left, their brains should tell them otherwise. Scientist Carl Sagan once quipped, “I try not to think with my gut.” Older fighters would be wise to do the same, and listen to their brains instead. There is wisdom with age, but be careful how much you pay for that wisdom along the way. When the decision to retire becomes all too obvious, chances are the price paid for that certainty was already too high.
–The Fight Scientist