Lawrence Kane is the author of Surviving Armed Assaults and Martial Arts Instruction, and co-author of The Way of Kata (all from YMAA). Over the last 30 or so years, he has participated in a broad range of martial arts, from traditional Asian sports such as judo, arnis, kobudo, and karate to recreating medieval European combat with real armor and rattan (wood) weapons. He has taught medieval weapons forms since 1994 and Goju Ryu karate since 2002. He has also completed seminars in modern gun safety, marksmanship, handgun retention and knife combat techniques, and he has participated in slow-fire pistol and pin shooting competitions.
Since 1985, Lawrence has supervised employees who provide security and oversee fan safety during college and professional football games at a Pac-10 stadium. This part-time job has given him a unique opportunity to appreciate violence in a myriad of forms. Along with his crew, he has witnessed, interceded in, and stopped or prevented hundreds of fights, experiencing all manner of aggressive behaviors as well as the escalation process that invariably precedes them. He has also worked closely with the campus police and state patrol officers who are assigned to the stadium and has had ample opportunities to examine their crowd control tactics and procedures.
To pay the bills he does IT sourcing strategy and benchmarking work for an aerospace company in Seattle where he gets to play with billions of dollars of other people’s money and make really important decisions. Lawrence lives in Seattle, Washington with his wife Julie and his son Joey. He can be contacted via e-mail at email@example.com.
This article covers shock blocks and is adapted from Lawrence’s great contribution to the must read book “Fighter’s Fact Book 2: Street Fighting Essentials” which was written and edited by Loren Christensen. It is a great book and a great article and I’m very grateful to Lawrence for sharing it with members and visitors to this website.
All the best,
Shock Blocks by Lawrence Kane
“Try to understand this. If you wait for the attack, defend against it, and only then go in the attack by parrying and striking, you are making extra work for yourself. Moreover, there is always the possibility of missing the ‘block.’ If you approach the enemy with the attitude of defeating him without delay and with utter resolve then you will certainly be a better position to finish him off. ” – Miyamoto Musashi
The reality of a real fight
Real violence sucks! If you lose a street fight, the result could be considerable pain, debilitating injury, disfigurement, or even premature death. If you successfully defend yourself, your attacker will often try to press criminal charges or pursue civil litigation, leading to significant expenses, adverse publicity, and oftentimes irreparable harm to your reputation. You might spend time in jail or even in prison. There is also the potential of long-term psychological trauma should you maim or kill someone. Consequently, fights are best avoided. Unfortunately you don’t always have the option of walking away. Bad guys simply don’t play fair. They cheat to win, attacking the weak and ambushing the unaware. Once they get the jump on you, bad things inevitably happen.
Working stadium security since 1985, I have witnessed or interceded in well over 300 violent altercations and have yet to see a combatant try to throw only a single blow, even if he knocked out his opponent with the first strike (a rare occurrence). Assailants often move faster, strike more suddenly, and hit more powerfully than you’d expect. Consequently, trying to successfully counter after an adversary has already ambushed you is extraordinarily challenging, particularly if you are already stunned, injured, trying to make sense of what just happened, or out of position from the force of his initial blow(s).
Even if you manage to block the bad guy’s first or second strike, there is inevitably another punch or kick already on its way. You are effectively behind the count before you even begin fighting back. To counter his offense, you need to (1) observe his motion, (2) orient, mentally digesting what is happening in order to formulate a response, (3) decide how to execute that response, and (4) act, performing a technique with which to defend yourself. It’s a four step process: observe, orient, decide, and act, or OODA Loop, as it’s termed.
This process of observing, orienting, and deciding takes a certain amount of time, even a fraction of a second, before you can act in a coherent manner. As a flurry of blows comes in, it is easy to get stuck in the observe/orient stage, falling farther and farther behind as each new blow makes you begin the cycle over again. You see the punch, begin to formulate a response, get hit, and then see another punch or kick coming. Before you begin to respond to each new blow you’re already encountering a new situation. Consequently once you get behind in a fight it becomes progressively harder to regain momentum, particularly once you are injured or badly out of position. Okay, that’s the bad news.
Continuum of responses
The good news is that martial artists (budoka) can train to the point where they can near instantly react to a threat without much, if any, conscious thought. It’s not easy to achieve that level of proficiency but over the long term all advanced practitioners eventually get there. In Japanese this is often described as a continuum of responses going from go no sen , to sen no sen , and ultimately sen-sen no sen .
Go no sen means “late initiative,” blocking and riposting after an adversary has already attacked. This is the method that almost all new martial artists are initially taught. It means to receive or block a blow and then to strike back. It is a great learning method, because it breaks advanced techniques down into small movements, but it is not practical on the street where you are likely to become overwhelmed by a determined aggressor. This is elementary martial arts (budo), abandoned quickly once any significant level of skill has been achieved. Unfortunately, if you miss an opponent’s tell or walk into an ambush this is the best you can do at the beginning of a fight.
Sen no sen means “simultaneous initiative,” intercepting the adversary’s blow just after it begins. This is an intermediate form of budo , using quickness and power to simultaneously attack and defend, cutting off the opponent’s strike before it makes contact. This is where we begin to find street-worthy application. It is the minimum we want to strive for in a violent encounter.
Sen-sen no sen means “preemptive initiative,” cutting off a blow before it even starts. It looks an awful lot like a first strike yet is still a defensive movement. Practitioners sense that an attack will be forthcoming and then cut it short before the aggressor has the chance to transform his mental desire to attack into the physical movement necessary to execute that desire, in other words disrupting the bad guy’s OODA cycle between decide and act. This is the ultimate goal of martial training insofar as self-defense is concerned; it is advanced budo .
Even better news is that a martial artist who has been caught flat-footed or who has not yet developed the ability to respond preemptively with sen-sen no sen can still turn the tide and regain lost momentum in a fight. We can do that through blocks that act like strikes, movements that simultaneously protect us from harm and cause damage to our adversaries. I like to call them “shock blocks.”
Preemptive initiative (sen-sen no sen) can be problematic on the street. While it is very useful for keeping yourself safe, it also looks like you are the one who started the fight, particularly to untrained observers. Never forget that the majority of witnesses who may oversee your confrontation will have no experience with violence beyond the occasional movie or television show. It is prudent, therefore, to consider how your actions might look to an independent observer who may be called to testify about you in court. Yelling something that sounds like you are a fearful victim rather than a crazed attacker may help. Consider shouting something along the lines of “Don’t hit me,” “I don’t want to fight,” “Get away from me,” or “Help, he’s attacking me” even as you strike.
As trained martial artists we have an obligation to understand not only how to hurt someone, but also to know when it is appropriate to do so. If your adversary has the ability and opportunity to harm you, places you in imminent jeopardy, and leaves you with no safe alternatives other than fighting, you have a pretty good case for the use of countervailing force in the eyes of the law. However, you must be able to articulate clearly how you knew your adversary was about to attack. You cannot just say that you had a feeling; you must be able to make clear to a police officer and a judge what tangible actions you saw that indicated he was about to attack.
Before I describe how shock blocks are performed, it is important to point out that there really is no such thing as a block in traditional martial arts, at least not in the commonly understood sense. The Japanese word uke means “receive” rather than “block” as it is commonly, though incorrectly, translated. Your defensive technique receives the attack and makes it your own. Once you own the attack, you can do with it what you will. A fast, hard block, therefore, has the potential to drop an opponent in his tracks, ending the fight before you even need to throw what is commonly thought of as an offensive blow. The most successful of these applications keep you from getting hit while simultaneously stopping your adversary from continuing his attack.
A shock block in action
As you can see, focused, hard-hitting blocks are really attacking techniques, causing pain and disruption to the assailant so that you can retake momentum. I saw a great example of this type of defense during an altercation at a college football game in 1993. A drunken fan of the visiting school (whose team was losing) became belligerent, jumping up and down on the bleachers, taunting a home team’s fan who was standing one row behind and slightly above him, and screaming obscenities at the crowd.
I had noticed the escalating confrontation, but before I could gather a team together to react, the drunk spun around and threw a roundhouse punch at the other man, putting all his weight into the blow. In one smooth movement, the other guy shifted slightly and executed what looked like, from my vantage point some 50 feet away, just a basic block.
The result, however, was far removed from any basic technique. The drunk staggered forward, let out an ear-piercing shriek that I could easily hear over the roar of the crowd of 72,000, and collapsed to his knees clutching his injured limb. The man who executed the block saw us coming, rushed down the stairs, held his arms placatingly in front of himself, shouting something along the lines of, “Hey man, I never punched him,” and beat a hasty retreat out of the stadium, no doubt thinking that we were about to arrest him. I actually had no intention of doing that, but he bailed nevertheless. His erstwhile attacker turned victim, on the other hand, was not so lucky. He was rushed to the emergency room to deal with his dislocated elbow and subsequently arrested (beyond the physical altercation he initiated, he was also underage and quite drunk with a blood alcohol level well over twice the legal limit).
When receiving attacks from an adversary, most classical martial systems use a check/control type of methodology. The hand that is closest to the adversary (e.g., just punched or blocked) performs the actual check, jam, or deflection, while the hand that is in chamber executes a technique designed to strike the opponent and/or control his limb. The arm-break block that I witnessed at the stadium was performed in this manner. The man who was attacked checked the incoming blow with one hand, pressing the limb to immobilize it for a split second, then struck hard enough with his other arm to hyperextend and damage his adversary’s elbow.
The following is a more detailed description of the technique that I believe he used (he was too far away for me to be absolutely certain). We’ll assume the bad guy has thrown a right-handed punch as happened at the stadium. If it comes in from the left side simply reverse which arm you use for each portion of the technique. You can block with either arm, of course, but you cannot get leverage against the joint to damage it if you pick the wrong side. If that should happen, the second movement would have to be altered into some other type of strike. This application has been broken down into three steps for clarity but it must be performed as one continuous movement in order to be effective on the street. Here’s how it works:
First, check the incoming blow with your left hand, pulling it in and down. Second, control the limb by shooting your right hand up underneath as you would do for a normal chest block (chudan uke). Make sure your motion is out, across, then back in an elliptical movement rather than straight across. Third, set the block while pivoting your body to hyperextend your opponent’s elbow. In order to achieve maximum impact it is important to leverage with your whole body rather than just your arm, particularly if your adversary is bigger and/or stronger than you. In practical reality you may or may not be able to damage the joint with this technique, yet done properly it will, at minimum, disrupt the follow-on blow, giving you a moment to counterattack. At best it will dislocate your adversary’s elbow in the same fashion I witnessed at the stadium, ending the fight.
Simple works best
When both your limbs are in play you gain an inherent advantage in thwarting a bad guy’s attack, typically making the most of a check/control or check/strike technique in doing so. While the resultant application could be an arm break, it is more common for it to be a strike. In this fashion, a head block (jodan uke), for example, can be performed with a deflection from the lead hand followed immediately by a forearm smash to the bad guy’s head with the other arm. In an ambush situation, however, this type of thing does not always work. You may only be able to make contact with one limb before being struck again, so I will focus on techniques that can strike or control using only the hand that makes first contact. If that first contact is sufficiently damaging, that will be all you will need to regain control of the encounter and set yourself up to escape to safety (possibly immediately but more likely after thumping the other guy at least once more in the process).
Shock blocks work because they are based upon simple body movements that can be performed under the affects of adrenaline. Since your heart rate can easily double in less than half a second during a sudden violent encounter, it is important to use straightforward techniques that will remain effective under extreme stress. Adrenaline can make you tougher, more resilient, and more or less impervious to pain in combat, but it also degrades your motor skills, hand-eye coordination, precise tracking movements, and exact timing, making complicated techniques very challenging if not impossible to perform. Simple, straightforward applications, on the other hand, remain quite feasible, particularly those involving pre-programmed muscle reflex actions.
Duel in the sun
Following a time honored tradition of dueling (kakidameshi), budoka in ancient Okinawa routinely tested each other’s fighting skills through actual combat. Like the feudal samurai before or the Old West gunfighter that would follow, the more famous the practitioner, the more often he was challenged to combat by those seeking fame. These fights were sometimes initiated by ambush and were often to the death, so such confrontations were not undertaken lightly.
According to legend, famed Shuri-Te karate master Itosu “Anko” Yasutsune traveled to the port city of Naha in the summer of 1856 to find relief from a particularly long period of heat and unbearable humidity. He found a large rock that provided some relief from the sun, settled down to enjoy the ocean breeze, and was about to doze off when he overheard several of the local villagers cracking jokes and disparaging Shuri karate.
Insulted by this banter, he decided to uphold the honor of his style by challenging the local champion, Naha-no-Tomoyose, to a duel. Making his way to the challenge area (ude-kake-shi), he made himself known to the crowd by quickly defeating three lesser practitioners in order to attract the local champion’s attention.
When Tomoyose arrived on the scene, Itosu discovered to his chagrin that he faced a much larger, more powerfully built opponent. He realized that he would need to end the fight quickly or risk becoming overwhelmed by Tomoyose’s superior size and strength. As the fighters began to circle each other, members of the crowd observed this disparity too, wagering at odds of ten to one against the challenger from Shuri. Tomoyose threw the first blow, a mighty lunge punch (oi tsuki). As Tomoyose’s fist came screaming toward his head, Itosu shifted aside and blocked with a sword-hand technique (shuto uke), neatly breaking his adversary’s arm. The crowd heard a loud snap, like the breaking of a branch, and the fight was over. This great victory, won through a basic block, solidified Itosu Yasutsune’s reputation for all time.
There are two major types of shock blocks. I like to categorize them as torques and weight drops. In physics, torque can be informally thought of as “rotational force,” which is why I use this terminology even though it may not be precisely correct in the world of science. It’s the rotation that is important, working much like the crack of a whip. Examples of torquing techniques include things like rising head blocks jodan uke) and inside forearm blocks (uchi uke).
Weight drops use the effect of gravity and bodyweight to amplify your striking energy, much like boxing legend Jack Dempsey demonstrated with his drop-step in the ring. Examples of weight drops include palm-heel blocks (shotei uke), mountain blocks (yama uke), backhand blocks (ura uke), and press blocks (osae uke).
Some techniques combine both torque and weight drop. A good example is a down block (gedan uke) when performed as you drop into a low posture such as sumo stance (shiko dachi). We will go through each of the aforementioned examples in detail in a moment. A couple more principles need to be explained first. When you perform a blocking movement you will either be opening your opponent up or closing him down.
To open means that you are on the inside of your adversary’s arms giving outward pressure, while closing means that you are on the outside of his arms giving inward pressure. If you open the opponent you expose his centerline, facilitating your attack yet leaving yourself more vulnerable to a counter threat. The centerline contains high-value targets such as the eyes, throat, solar plexus, and groin.
If you close your opponent, on the other hand, your maneuver cuts off his attack, leaving you comparatively safer. On the downside there are fewer vital areas to aim for with your follow-on technique. You should still have access to decent targets such as the side of the head, floating ribs, kidneys, or knee. While the tactical situation will often force you to take whatever opening your opponent gives you, less experienced practitioners are usually best off closing for safety while more experienced practitioners may be best off opening to more quickly end the fight.
One last item before we get to the technique descriptions. To be most effective, contact must be an aggressive, powerful movement, much more like a strike than a block. It must cut off the attacker’s technique before it gains too much speed and power, catching it as close to his body as possible. Even though I use the term “block,” think “strike” as you perform these techniques.
Torque blocks use rotational force to shock your opponent, causing pain and disruption that may enable you to regain momentum and take control of the fight. To get a feel for how this is done, have a partner throw a half-speed punch at you. Hold your arm out and up, like you are a weightlifter flexing your biceps muscle, and then rotate your upper body to bring your arm straight across and cut off the blow with the inside of your forearm, hitting with the meaty part of your upper arm and then pushing through. This movement should readily deflect the punch but not hurt your partner.
Now try it again a little differently. As soon as you make contact with the incoming punch, immediately rotate your arm inward so that the ulna bone (outside of the arm on the little finger side) makes contact with the incoming limb. Make this revolution quick and explosive, tensing your whole body as you complete the rotation. Even at half speed this should be painful to your partner if you do it correctly.
Jodan uke (head block): This is one of the simplest torque blocks you can perform and is also one of the first taught in traditional karate schools, most likely because the initial blow in most fights is a strike to the head. Not only is the head a high-value, easily damaged target, but it is also a psychologically compelling one. Performed one-handed, jodan uke is very much like a punch. To begin the technique, the leading arm closest to your opponent moves straight up, palm facing inward toward you. As your fist passes head height, your arm rotates over at an angle with your elbow pushing out such that your fist remains centered above your forehead. Finally, the forearm arm rotates outward, palm facing toward your opponent. This last movement generates most of the torque.
It can be performed as an opening or closing technique, of course, but I will show an opening technique in this example. If you move in on your adversary to close distance and your contact provides sufficient shock, you should be able to disrupt the integrity of his stance. Physiologically this will force a small delay before his follow-on punch can come in with any force, as he will have to straighten, re-align his spine, and then throw the blow. During this momentary disruption you will be able to counterattack. In this example the counter is a simple strike from the off hand:
Uchi uke (inside forearm block): This is another great torque technique that is performed in the same fashion as the drill I described at the beginning of this section. Because we can physiologically move outside-in (toward our centerline) faster than we can move inside-out (away from our center), it is naturally quick and very useful in a surprise attack. An instinctive follow-on is a sword-hand strike (shuto uchi). In some forms (kata), such as hookiyu andgekisai , this movement is combined with a simultaneous sweeping movement to extend the opponent’s leg and stomping movement to damage his knee and/or ankle. While attacking both high and low at the same time in this fashion is much more effective than either technique alone, we’ll focus solely on theuchi uke for the moment.
Like the previously described jodan uke, uchi uke can be performed as an opening or closing technique. In this case I will show a closing example. Once again, if you move in on your adversary to close distance and your contact provides sufficient shock, you should be able to cause a great deal of pain and disruption from this application. During this momentary disruption you will be able to counterattack. In this example, the counter is a sword hand strike commonly seen in kata. While it may not be obvious while performing the kata, this application is typically an elbow strike (hiji ate) and then a shuto uchi, performed as one continuous movement. You simply lead with the elbow and the rest happens naturally.
As mentioned previously, real fights are not static events. While a single application may certainly be able to end the confrontation, you simply cannot count on that happening every time. Consequently combinations of techniques become very important. The aforementioned jodan uke and uchi uke make an excellent combination. It is natural, quick, and relatively easy to perform.
Here is an example of using the uchi uke to open an opponent with a follow-on jodan uke that, in effect, becomes a forearm smash. While shown in two steps it is performed as one continuous movement, using the bounce as the first block contacts your adversary’s limb to facilitate a faster riposte with the second movement. Done properly, the first strike should be disruptive enough to give you time for the second which will hopefully end the fight, or at least put you on solid ground for doing so.
These blocks use gravity and bodyweight to amplify your striking energy. To be most effective, you will need to be extremely rigid at the moment of impact, connecting your arms to your body and aligning your spine so that all of your weight is transferred through your limb. If your body is loose, your arm will flex, diffusing much of your power. To get a feel for how this is done, place your hand against a partner’s chest and push him backward using just your arm strength while your partner moderately resists (holding good stance, not punching or pushing back at you). Begin by standing close enough to your partner that you have plenty of room to extend your arm without having to step forward to move him.
Now try the same thing again but put your whole body into it, dropping forward into a low posture such as sumo stance (shiko dachi). Be sure to move all your body as one unit so that your arm does not push all by itself. The power should come from your hips and bodyweight through your forward and downward movement. Done properly, you should notice that while pushing with your arm alone is good, pushing with your whole body is much, much better. Try it again with your partner strongly resisting (by stance alone) to get a good feel for the technique.
Shotei uke (palm-heel block): This is a basic but very effective weight-drop block. It is often performed as a strike to the opponent’s shoulder, pectoral muscle, or upper arm to cut short his attack, using a weight drop into shiko dachi for added emphasis. It can easily be followed-up by a blow from your off hand. In practical application, this technique must be performed with preemptive or simultaneous blocking. Used responsively, you will land your blow too late, almost assuredly getting hit on your way in by either the initial strike or its follow-on. When done properly, however, it can be very disruptive to your opponent. When you drop in place, throwing your arm out as your weight drops it can be extraordinarily fast, too. Body drops, arm shoots out. A good follow-on blow is to rotate your hips over into a forward stance (zenkutsu dachi) and punch with your other hand.
Yama uke (mountain block): This is an outstanding weight-drop block, somewhat safer than shotei uke since you automatically protect your head better in case you fail to connect with the incoming blow or otherwise mistime your technique. It is more offensive too, since it contains a simultaneous elbow strike. Furthermore, it has the additional benefit of working off your natural flinch reaction; many people automatically duck and cover their head when startled. In both cases you are dropping to shiko dachi , a rather immobile stance, so you must not only be very close to your opponent but also strike swiftly and strongly so that you do not get caught flat-footed.
Yama uke can be very powerful on the street when you drive forward into or through your opponent. You not only strike with your lead elbow but may also be able to connect against your adversary’s legs or groin with your knee, depending on what type of stance he uses. Because you are so close, your rear arm (the one farthest away from the enemy) actually performs the defensive technique. If your lead elbow connects with the opponent’s solar plexus you may not even need a follow-on offensive technique. While he is gasping for air you can escape to safety.
Ura uke (backhand block): This is most effective when you shift off the line of your opponent’s main force, striking downward at an angle. This technique is frequently performed in cat leg stance (neko ashi dachi) to facilitate a simultaneously swift evasion and body drop. Because this stance is very mobile, it is relatively easy to follow-up with an offensive technique. In practical application, it is important to think of this as a strike rather than a block. You are either evading the incoming blow or checking it with your off hand (or both) and then blasting down on the adversary’s arm with the back of your wrist. Your weight drop into neko ashi dachi facilitates power for your technique and there are several pressure points along the arm that you may be lucky enough to hit as an added bonus.
A common follow-on technique is an uppercut (age tsuki). This is often performed by striking again with your off hand to momentarily pin the opponent’s arm while simultaneously shooting out the age tsuki with the hand that first blocked. If you shift forward into a more solid stance such as sanchin dachi(hourglass stance) your follow-on blow will have even more impact.
Osae uke (press block): This is generally considered an advanced weight-drop block. This is because the press is often executed with an internal weight drop where you lock into your stance, align your body, and lower your center of gravity, rather than as an external one where you drop in place by shifting to a lower posture. Even if you do drop into a low stance to take advantage of an easier to perform external weight drop, osae uke is executed by striking downward with your palm. This application requires more accuracy than blocks which utilize your whole arm. It is often performed in kata with a simultaneous palm heel strike (shotei uchi). As one hand drops downward to perform the press the other shoots out to strike your opponent.
In practical application osae uke is frequently used as an opening technique where you hold your ground, simultaneously cutting down the incoming attack and striking back with shotei uchi. Like ura uke, you may be able to hit a pressure point on the arm for added affect. As the techniques finish, your body should be rigid with arms extended, one downward and one outward. Your shotei uchi strike may end up becoming a block if you have mistimed the application or your opponent turns out to be faster than you thought. Strike or block, either way it can keep you safe.
Some defensive techniques use a combination of both torque and weight drop for added effect. The rotational energy of the arm movement is combined with the gravity/bodyweight drop to amplify your striking energy even further than can easily be done with either application alone. This becomes very important when working against a much larger or stronger opponent, or in cases where you wish to defend against a kick with an arm technique by striking rather than deflecting the adversary’s energy with a sweep block (gedan barai uke) or hook block (sukui uke).
A good example of a combined torque/weight drop technique is the traditional down block (gedan uke). It works by both dropping into a low stance, such asshiko dachi, as well as driving the arm down with rotation at the point of impact. In this case, the torque is nearly identical to a jodan uke . You get more power if you use a push/pull technique (hikite) by simultaneously pulling your off hand into chamber.
This is a very common technique found in a plethora of kata yet it is much more powerful than many practitioners imagine. It can be used offensively or defensively, as a strike or even as a throw. For example, your arm returning to chamber may have an opponent’s hand or arm captured in it rather than just using hikite to increase your shocking force. To stick to the theme of shock blocks, however, I will demonstrate only an impact application, using gedan uke to defend against a kick.
When performed in this fashion, you will frequently turn off-line away from your opponent’s force and then strike his leg as it passes through the space where you just stood. You should tense your whole body at the moment of impact for best effect. This can be very powerful, indeed. In fact I have nearly had my leg broken in this manner by someone who wasn’t even trying to hit all that hard. Of course he’d been doing this for more than 40 years so his light taps are stronger than most folk’s full-strength strikes. Nevertheless, it’s a robust technique, one that should not only shock the leg but also knock your adversary off balance if you do it right, facilitating your escape.
The faster you can dispatch your opponent in a real-life confrontation the safer you will be. To be most effective, your technique must simultaneously be able to keep you from getting hit while preventing your opponent from continuing his attack. That is why you should think of your defensive applications not as blocks, but rather as strikes. The Japanese word uke means receive rather than block; a significant difference in more than just the terminology. Solid, well executed blocks can shock your opponent, causing damage and/or disruption that will let you regain control of a fight.
The two main methods of performing shock blocks utilize torque and/or weight drop to generate power, confound your opponent, and keep you safe. The applications I have described here represent a mere sampling of the various shock blocks found in budo. I encourage you to delve into your own martial art to find more. Tandem practice in the training hall (dojo) is a great way to internalize these techniques, facilitating your ability to use them effectively, should you ever need to do so, on the street.