Stephen Thompson and Darren Till’s March meeting in Liverpool was one of the most anticipated fights of 2018 but it played out as a tentative staring contest. Thompson has re-emerged in the past week, however, to drag a point of contention back into the MMA headlines. The two-time welterweight title challenger announced that he had suffered an MCL tear as a result of a Darren Till side kick to his knee joint and concluded:

“I honestly think that strike should be made illegal. It could end somebody’s career. You know Robert Whittaker had to have ACL surgery following his first fight with Yoel Romero due to that particular strike […] I think [sic] it an ugly strike and that it should be made illegal.”

This essentially confirmed something we had speculated on in a couple of our Tactical Guides before Thompson’s fights. Thompson’s kicking game is built around a Bill Wallace style triple attack of side kick, round kick and hook kick all from the lead leg, but he almost never takes the easiest target for the side kick: the opponent’s lead leg. In our Tactical Guide to Thompson vs Woodley II we noted:

Low line side kicks are easily the most frustrating kicks for wrestlers to deal with because they are only within grabbing distance for an instant, are longer than round kicks, and can easily be faked and followed with lead leg hook or round kicks. Unfortunately some fighters seem to feel honor bound not to throw them. Few fighters could benefit as much from utilizing them as Thompson, however.

Stephen Thompson isn’t alone in his opinion. Straight kicks to the lead knee have been contentious among fans and fighters alike since they started turning up around 2011. Since then there has been a constant back-and-forth over the legality and cheapness of the method.

The Injuries

Discussions of straight kicks into the knee joint are naturally divisive and those in favor of the kicks often take the idea to the most ridiculous possible conclusion for effect by saying things like, “Why don’t we just ban punches to save on brain damage?” Obviously this overlooks the general agreement we have over various other techniques which are banned and most fans are completely fine with not seeing. Groin shots are prohibited in MMA and have been since very early on. As is the case with any form of small joint manipulation.

Groin strikes and finger wrenches are perceived to be disproportionately effective, but fighters weren’t winning early no-holds-barred bouts with crotch punch TKOs and finger-lock submissions. Instead they are techniques which seem to offer long term damage to quality of life without much immediate benefit. Any fighter competing in the UFC or Bellator is tough enough that they will let you snap their finger at any of the joints and carry on fighting. But then if hitting cups and snatching at digits to defend chokes were legal any fighter with ten or so fights would probably struggle to sign his own name and be sterile. Most crucially though, it is just not entertaining to watch guys trade knees to the crotch in an over under clinch. Perception means a great deal in a barely legal fist-fighting sport and while knees to the head of a downed opponent are no more dangerous than they are to a standing opponent, the public didn’t like them so we now aren’t allowed to enjoy one of the most interesting techniques a good wrestler can use in the cage.

Whenever the idea of prohibiting straight kicks to the knee is floated, one of the most common counter-arguments is that there has never been a serious injury from a low line kick. That used to work pretty well, and certainly you aren’t going to see any knee-stomp fatalities, but a number of fighters have had significant interruptions to their careers through ACL or MCL damage directly related to these kicks. Such ligament tears are not the abrupt end of an athletic career in the modern era the way they might have been in the past, but they still require a good amount of time away from the sport to heal up. You only need to ask Mauricio Rua or Dominick Cruz how easy it is to re-injure a recently repaired ligament when you get back to training too.

In one of the tactic’s earliest high-profile outings, Quinton Jackson proved the perfect mark for it. His entire plan was to plod straight in on the taller Jon Jones and try to swing at him. Over the rounds Jackson took dozens of these kicks and never adapted to them, though he was able to prevent Jones from taking him down when the champion tried. That was until one kick visibly hyperextended his knee and then the takedown and finish came quickly for Jones. Jackson was one of the first fighters to complain about this kick and has since struggled with recurring knee injuries which allegedly set back his weight cut against Ryan Bader. Though as the Bellator heavyweight grand prix seemed to happen at least partly because Rampage refuses to get back in shape, it’s hard to know how much of that is recurring knee issues.

Robert Whittaker, of course, was forced out for an entire year by the combination of a knee injury—directly resulting from a Yoel Romero side kick—and an unfortunately timed staph infection during his recovery. Rather than complain about it, Whittaker came out in the rematch looking to stamp on Romero’s own leg at every opportunity.

In one of the first notable cases of such a kick being used (of course by a Jackson/Winkeljohn fighter), Adlan Amagov hyperextended Keith Berry’s knee in a move so surprising that it left Frank Shamrock and Pat Miletich musing over whether it was even legal. Berry was back in action a few months later but it almost immediately turned many fans off the kick.

Back in 2012, this writer had the opportunity to ask Mike Winkeljohn about the public perception of this kick and the great coach had this to say:

I definitely have my fighters throw a front kick to the knee. I see it as a very legit technique and not nearly as dangerous as punching or kicking someone in the head. I believe it is starting to add a new dynamic to the game because fighters have to worry about their base being taken out of their attacks even more than before. I also would rather have dinner in twenty years with a fighter who limps into the restaurant than with the fighter who can't remember his own name, because he never stopped his opponent's striking advances. The knee joint is very strong if people know how to defend that kick properly.

It is Stephen Thompson’s MCL tear at the foot of Darren Till that has this debate back in the MMA headlines, but a lesser known and perhaps more severe example is Teemu Packalen. After Marc Diakiese knee-capped him in the early going of their March 2017 fight, Packalen’s demeanor immediately changed and he ran onto a counter which saw him take a knockout loss. After the fight Packalen had surgery on his knee and was out for a few months. He was scheduled to fight again in October 2017 against Marcin Held but the knee took him out of action again.

We aren’t seeing the kind of bone-through-the-skin, inverted-knee-joint injuries that martial artists used to imagine would come from a side kick to the knee, but to pretend that thrusting connections to the knee joint don’t have the proven potential to cause massive damage is just daft.

Dealing with It

Here’s the truth, though: low line straight kicks probably aren’t going anywhere any time soon and they work very well. They work even better if your main defense is to be indignant that the kicker would even attempt such a thing against you. Many fans imagine these kicks as somehow unanswerable but there are, so far, a handful of proven ways to deal with them and the more fighters start using these on the regular, the less important the low line kicks will seem.

While low line side kicks have been around since the dawn of martial arts, Bruce Lee was one of the first martial artists writing extensively about this weapon in a striking context and it has taken fifty years but top mixed martial artists have demonstrated his ideas perfectly. Lee believed in standing southpaw, so as to lead with the strong hand and leg, and put the lead leg in line with the (normally orthodox) opponent’s lead leg. The low line side kick was therefore the longest, nearest weapon into the closest target. No one has yet found a way to step in and punch without planting the foot ahead of them, and I wouldn’t hold my breath on that breakthrough happening in the next couple of years. Lee’s entire self defense book consisted of him, in white jeans, being attacked in different locations and side kicking his assailant in the knee in almost every scenario. He even found a way to shoehorn it into an appearance on Longstreet.

Generally the low line side kick and oblique kick are at their best as a method to jam the opponent’s advance. Occasionally you will see fighters leaping in to attack with the low line side kick, but the answer to that is very simple: step back. This comes back to our favorite side-kicking comparison: Lando Vannata and Yair Rodriguez. Vannata will step on his opponent’s leg. Sometimes he will glide a good distance, sometimes he’ll just pick it up out of the stance, but it is there as an annoyance to set up other things. Vannata annoys opponents and can fake the side kick and glide in with punches, or step on his opponent’s knee and then spin into a wheel kick, knowing they may be close enough.

This sort of needling and nudging actually encourages Vannata’s opponents to overcommit and try to push through. The moment he takes that ramrod away he can try to run them onto a counter.

When Yair Rodriguez throws the low line side kick it is drawn up to his chest and stomped down with leg-breaking force. The problem is that you would have to be a dummy to stand there and take it. So Rodriguez tries to flow the low line side kick into wheel kicks and so on, but his opponent has always run a mile from the first attack and he is left wasting energy and looking flashy to no effect.

And that’s the key: if you aren’t timing the opponent’s lead leg placement with your kick you are just standing on one leg or stomping violently and uncontrollably into nothing. If all you do is leap in with side kicks, the opponent need only move. That’s what Robert Whittaker managed to do for every side kick after he had his knee destroyed by Yoel Romero. It doesn’t have to be an inch-perfect retraction of the lead leg accompanied by Saenchai-style mean-mugging. Simply getting the knee the hell out of dodge is enough—Whittaker was throwing his lead leg a mile behind him each time Romero jumped to initiate the kick.

Just as the traditional martial arts expectation of reverse knee joints was subverted the moment the low line side kick started being used in MMA, Whittaker showed us another neat trick that most wouldn’t have thought of as a viable answer to the side kick. Whittaker started entering, and countering, with a right front kick to the body. Most of us would think the last thing you want to do when taking a low line side kick is get up on one leg. When Michelle Waterson brushed a couple of side kicks on Rose Namajunas’s standing leg as Namajunas threw round kicks, it seemed like we might be on the verge of a horrendous knee injury. Yet Whittaker’s aggressive, pre-emptive front kicking seemed to prevent Romero from actually applying his weight to the kick.

The fact that he was really extending into the kick, getting more side on and leaving his standing leg behind him, also seemed to hide the target from Romero quite well. Both Whittaker-Romero fights contained dozens of instances of both men leaping in and colliding almost chest to chest. If the point of the low line side kick is to beat the opponent’s leg up and keep them at range, a deep front kick that carries the fighter into trading range seems a great answer. The best part is that the front kick doesn’t need to connect to the solar plexus or ribs, it just needs to be a whole footed stomp against the chest, shoulder, hip—anything that catches the opponent’s weight and forces it out of their kick.

The entire purpose of low line kicks, be they side kicks or oblique kicks, is that they stop an opponent from plodding into punching range. Whether they hit the knee, the thigh, or the crease of the hip, they throw the opponent’s hips back and break his posture momentarily. Holly Holm did this a few times to Ronda Rousey and it demonstrated perfectly that break of posture and need to reset while Holm was already moving away.

Considerate Holly Holm kicking into the thigh rather than the knee joint itself.

For any fighter from the Rampage Jackson school of complaining, for whom the low line kicks are cheap because they stop him from stepping in and banging, it would be good to make like Whittaker and jump in behind the front kick. You will end up in banging range anyway.

But if you are by chance not a plodding banger, you are already half way to beating the kick. The low line side kick and oblique kick are straight line kicks which immediately become more difficult if the target begins even slowly drifting to the left or right. Jon Jones stopped throwing low line kicks at Alexander Gustafsson because Gustafsson was constantly in motion and circling the cage. Instead Jones went to round kicks and back kicks—techniques with which it is far easier to put a lead on a circling opponent and that are far more forgiving. Jones still went to the low line straight kicks occasionally and, often because of Gustafsson’s constant feints, messed up his timing and ate punches on one leg. When Jones mistimed an oblique in the first round, Gustafsson parried it and stepped in to complete a takedown against Jones. Jones had never been taken down in the UFC before, but he was completely out of position due to his kicking with impunity against a guy who wasn’t just going to stand there and try to take it.

The low line straight kick can be used as a lead, but it is similar to the uppercut in that it is a counter to the opponent’s positioning. You can’t effectively uppercut a completely upright opponent, and you can’t kick the leg if it isn’t there. As with any other tactic in the book, low line kicking becomes considerably more difficult if the opponent is feinting. Putting the lead foot in and out—the old hokey pokey method—works well to frustrate fighters who are waiting to stomp on it. At present fans are convinced that the low line side kick is just an unstoppable force through every phase of the motion, but the margin for error is actually pretty slim. Pick the leg up and connect too late and you are just on one leg, stepping on the well-braced thigh of someone whose weight is already in on top of you. Poor Oliver Enkamp found that out after showing the kicks a couple of times against Danny Roberts.

In the second match between T.J. Dillashaw and Raphael Assuncao, Assuncao was having a hard time getting a read on the switch hitting American. So Assuncao opted to try mirroring Dillashaw’s stance and stepping on his lead leg to slow him down and keep him out of boxing range.

Assuncao’s job was made considerably more difficult by the sheer number of fakes and feints that Dillashaw used. Each time Dillashaw pumped a shoulder or showed a level change, Assuncao would look to counter, reconsider, and then reconsider again because Dillashaw was already on top of him. The constant changing of stances also made it hard for Assuncao to keep up with which foot was forward. Here Dillashaw picks up his lead foot and performs a switch step, stepping deep with his other foot and getting into boxing range. Assuncao actually tried to check hook T.J., but that draw of the counter and switch of feet would have worked even better if Assuncao had been looking for his side kick at that moment.

The low line side kick is best set up to work from mismatched stances—what we term "open guard" or "open stance." But when both fighters are orthodox or both fighters are southpaw, the lead-leg side kick has to be thrown across oneself which puts the fighter in danger of that cross-legged landing that Jon Jones suffered against Gustafsson. Whittaker surprised everyone by using the side kick across himself against Yoel Romero in their rematch but that was aided enormously by Romero offering a stationary target. When Dillashaw changed stances against Assuncao his lead knee—the target—was a foot and a half to the left or right of where it had been a second ago. That long, linear fencing game suddenly becomes Whack-a-Mole with a spear.

Finally, if a fighter can draw the low line side kick he can readily counter it. If the purpose of the side kick is to keep the opponent off, he knows it will come when he threatens to step in. Too many fighters are afraid to reach down and parry the low line side kick. The danger of the opponent going from side kick to high round kick is minimal—it’s a tough feat to perform in a fight and even Stephen Thompson only uses it when he and his opponent are in the same stance.

When in an open guard position the round kick—which is more flicking than thudding, anyway, because it has to change trajectory from the side kick chamber—tends to catch the opponent’s lead shoulder and back more often than not. The hook kick is a real danger, but the fighter can effectively reach down to parry the low line side kick while keeping his rear forearm high and wide. Effectively the low line forearm parry can be made into a shoulder roll with an extended arm. However a fighter opts to perform it, the result is that position Stephen Thompson dreads: the advancing fighter can slide down the back side of the side kick and attack his opponent from a dominant angle, while they are on one leg.

A final method for those who don’t have neat feet, don’t want to kick, and don’t have any idea what to do when faced with the low line side kick: keep your toes pointing forward. This is the difference between being pissed off and ground down by accumulation and having your knee busted up on the first kick. Just as having your lead foot toed in is the worst possible way to take round kicks, it is also the worst possible way to take straight kicks because you are taking all of the force of the kick on the side of the knee. If you’re getting kicked in the front of the knee you can try to keep that foot heavy and keep the leg bent. Obviously, you can’t bend your knee sideways.