The Science Behind Board Breaking

Legend has it that on the island of Bawean in ancient Indonesia, a woman named Rama Sukana was washing clothes by a stream when she observed monkeys engaged in fierce battles among the trees. Intrigued, she meticulously studied their fighting styles and started practicing them herself.

Perfecting her combat skills required dedication, and her delayed return home left her husband furious and starving. Overcome with rage, he refused to hear her out and launched an attack.

Rama Sukana swiftly employed her monkey-inspired techniques to subdue him. Her repeated success eventually wore him down, and he requested lessons in her innovative hand-to-hand combat style. This marked the birth of the Indonesian martial art, pentjak silat [source: Blackbelt Magazine].

During the 16th and 17th centuries in Japan, the government, fearing armed rebellions, opted to disarm the populace. While peasants were unlikely to challenge sword-bearing Samurai unarmed, they faced a new dilemma: protecting themselves from bandits. Their solution was karate, meaning "empty hand" [source: Biryukov].

It’s perhaps no coincidence that these legendary origins are tied to two martial arts renowned for "tameshiwari," the awe-inspiring act of breaking boards, bricks, and concrete slabs barehanded. Born from the need to combat domestic abuse and lawlessness, pentjak silat and karate were crafted to empower the defenseless. In uneven battles, the underdog must rely on unconventional tactics. Tameshiwari showcases the extraordinary power these methods can unleash.

Why chop wood with bare hands when we have axes for that?

Imagine a martial arts practitioner, let’s call her Jane, who has trained diligently and achieved a high level of skill. One day, after leaving her training studio, Jane is ambushed by a group of thugs around a corner.

Thanks to her rigorous training, Jane’s body reacts instinctively before fear can set in. She swiftly escapes Thug 1’s grip, pivots, and delivers a powerful kick to his knee, causing it to buckle with a gruesome crunch as he falls. Thug 2 lunges at her, but Jane doesn’t retreat. Instead, she engages, closing the gap, sidestepping his attack, and using her shoulder to deflect his momentum while smashing her elbow into his face, shattering his nose.

Thug 1 is now incapacitated, unable to walk, while Thug 2 lies on the ground, blood pouring from his broken nose. Both are writhing in agony. As Jane stands victorious, adrenaline coursing through her veins, she hears applause. Her sensei steps out of the shadows, awards her a black belt, and students quickly remove the injured "thugs" from the scene.

Of course, this scenario is entirely fictional. However, it reflects the kind of real-world situations martial arts training prepares individuals to handle. While an ambush might seem like the ultimate test of a student’s skills, it’s fraught with practical and ethical issues, such as the risk of severe injury and the difficulty of finding willing participants. Moreover, the possibility of a student failing under pressure could lead to disastrous consequences, something no dojo wants to risk.

To circumvent these challenges, many martial arts have adopted board-breaking as a testing method. Viewed in this context, it’s a logical solution. Instead of causing harm to others, practitioners can demonstrate their power and precision by breaking pieces of wood.

When teaching beginners to break boards, instructors focus on overcoming the natural fear of self-inflicted pain. Striking a solid object with full force using bare hands isn’t instinctive, and the fear of injury is well-founded. To succeed, students must channel their energy correctly, applying precise force and follow-through. Surprisingly, the small bones in the hand can endure immense stress—up to 40 times more than concrete, as incredible as it may sound [source: Newton's Apple].

After mastering the basics, students progress to the intermediate stage, where they start breaking larger quantities of materials. The greater the number of objects, the more force and concentration are needed. Instructors must monitor students closely during this phase, as overconfidence can lead to serious hand injuries.

From there, students refine their energy and focus until they can shatter a massive stack of concrete blocks with a single strike. This isn’t an exaggeration—people genuinely achieve this. Board-breaking has evolved into a competitive discipline, with global events showcasing incredible displays of power and precision [source: Serrano].

But how is this possible?

How can hands break boards to pieces?

Imagine this scene: A man stands atop a platform, towering over seven enormous ice blocks, each weighing close to 300 pounds (136 kilograms). With his hands clasped behind his head, he bends forward, touching his forehead to the top slab. After several repetitions, he finally drives his skull into the ice with full force. Astonishingly, all seven blocks shatter and crash to the ground.

This actually occurred. J.D. Anderson, known as the Iceman, shattered 2,000 pounds (907 kilograms) of ice using only his head on "The Tonight Show with Jay Leno." While this feat is extreme and not advisable (see How Chronic Traumatic Encephalopathy Works), it highlights the extraordinary power the human body can achieve through training and focus.

Breaking boards with your bare hands is far simpler and less risky than the ice-shattering stunt described above, though your hands are still valuable and should be protected. Beginners typically start with a single pine board, about 1 foot (30 centimeters) wide. Pine, a softwood, is much easier to break than hardwoods like oak, and the board should be free of knots for optimal results.

Students can employ various techniques, such as the "hammer fist" (driving a clenched fist downward), "palm heel" (striking with the base of the palm), or "knife hand" (the classic karate chop). The board can be held by someone or placed on supports, but it must be secured on the sides to allow breaking along the grain. Attempting to break against the grain is significantly more challenging.

No matter the technique, instructors stress the importance of preparation through practice. Repeated strikes on padded surfaces help improve accuracy, speed, and strength while conditioning the striking area of the hand or foot.

Mental readiness is just as crucial as physical preparation in this context. Delivering an accurate strike demands intense concentration. Practitioners enhance their focus through specific breathing methods, such as exhaling sharply or even yelling during the strike.

When breaking a board, striking near the center is essential. A major mental hurdle is overcoming the body’s natural tendency to slow down before hitting a hard surface to prevent injury. Ironically, slowing down prevents the board from breaking, causing the force to rebound and injure the hand. To counter this, instructors teach students to aim not at the board itself but at a point a few inches beyond it. Visualizing this target helps maintain speed and ensures follow-through, transferring the full force of the strike to the board and breaking it without harming the hand or foot [source: American Martial Arts Academy].

While technique is important, it doesn’t fully explain how soft, flexible body parts can shatter hard objects.

Board-breaking Physics

What is a newton, exactly? No, not the delicious cookie, but the unit of force. Specifically, a newton is the force required to move one kilogram of mass one meter [source: Merriam-Webster]. Interestingly, this is roughly the same force as the legendary apple that supposedly struck Isaac Newton, leading to his discovery of gravity. Coincidence? Perhaps. But that’s another tale. The newton is relevant here because it helps measure the force needed to break objects like boards.

In the 1970s, two physicist-martial artists combined their passions to study board-breaking. They questioned how humans, with their relatively weak hands and feet, could overpower solid wood. The key advantage lies in speed. Revisiting Newton’s principles (Isaac, not the cookie or the unit), we recall that force equals mass multiplied by velocity. Essentially, the faster a punch, the greater its impact. But how fast is fast enough?

Their research revealed that a beginner in karate can achieve a hand speed of 20 feet (6 meters) per second, sufficient to break a standard 1-inch (2.5-centimeter) pine board. Some students even use reusable plastic boards designed to break under similar stress.

One of the physicists, Ron McNair (who later tragically died in the Challenger space shuttle disaster), was a black belt. He could execute a karate chop at 46 feet (14 meters) per second, generating 2,800 newtons of force. To put this in perspective, only 1,900 newtons are needed to break a 1.5-inch (4-centimeter) concrete slab.

As previously mentioned, speed alone isn’t enough. Even combined with accuracy, it’s insufficient without follow-through. This isn’t just about overcoming fear of injury; it’s about countering the natural tendency to slow down. Another physicist-martial artist discovered that a hand reaches peak speed at 80% of its strike trajectory. This underscores the importance of aiming beyond the board’s surface to ensure maximum force transfer.

When a hand or foot strikes the board at the perfect spot with sufficient speed, the wood, like all materials, begins to vibrate until it reaches its breaking point. Once the material’s elastic limits are exceeded, it gives way with a loud snap, surrendering to the force [source: Rist].

This is how board-breaking is achieved. But the bigger question remains: Why do it? While proponents argue it’s a valuable measure of skill, is breaking boards truly beneficial or necessary?

Is board-breaking a good idea?

One apparent reason for incorporating board-breaking into martial arts training is that it provides a safe, controlled way to assess students’ progress without sparring. However, not all instructors agree. Some strongly oppose board-breaking for various reasons.

One concern is the potential danger, particularly for children. The human hand is a marvel of complexity, with 27 small bones enabling remarkable dexterity. Capable of intricate tasks like playing a violin, performing surgery, or crafting delicate items, skeptics argue that the hand is too valuable to risk by repeatedly striking hard objects. It’s a part of the body we should protect for future use.

Board-breaking isn’t without risks. Critics highlight cases where young martial artists have fractured carpals, metacarpals, and proximal phalanges (bones in the palm and fingers). Should we endanger the hands of future musicians, drivers, doctors, artists, or writers?

Another critique of board-breaking, often introduced at beginner levels, is that it promotes the idea that performing flashy but meaningless feats is commendable. Critics argue that board-breaking has no practical application in real-life scenarios. As Bruce Lee famously remarked, "Boards don’t hit back." The essence of martial arts lies in self-defense, not breaking wood. Students should focus on improving agility, speed, fitness, and technique to achieve this goal.

Skeptics suggest that the real appeal of board-breaking for instructors lies not in assessing progress but in its visual impact, serving as a promotional tool to attract new students [source: Salick].

While some objections hold merit, the claim that board-breaking is inherently dangerous lacks solid evidence. Although specific statistics on board-breaking injuries are scarce, studies on martial arts safety generally indicate that injuries are mostly minor, such as bruises and cuts. Research suggests that martial arts, especially karate, are relatively safe [source: Zetaruk]. Given that tameshiwari is a common aspect of karate training, it’s likely that board-breaking is safe—provided proper preparation and practice are observed.