I am a 3rd Degree black belt in Taekwondo and regularly break both wood and concrete. I have a few questions that I wonder if you or another might know the answer to? I have three questions
When stacking concrete slabs with spacers, how much force does it take to break the first and, is the same force required for each succeeding slab in the stack?
Also, I keep hearing people speak of striking and then immediately retracting the striking hand (foot) to limit its contact time and ability to reabsorb the energy. This seems counter-intuitive to me since when you power break stacks of concrete you make a deliberate effort to involve not only your whole body mass, but also to drive all the force through your target (and only stop after all has broken). Can you explain these two seemingly different approaches to contact time?
With this in mind, might we suggest that the concrete is broken both from the shock-wave of energy and from the ensuing mass that follows - or is there no such thing as kinetic energy being transferred without continual contact time on the target?
First, breaking concrete is not the same as striking an opponent. Breaking is a training tool (or at least that was its original intention; now it is just entertainment); just as lifting weights is a training tool. As training tools, they add to your striking power, but there is little correlation between any training tool and the actual action that they train, which in this case is striking another human. Lifting weights will add to your strength and mass, which will increase your striking force, but it does not training your actual striking technique. Breaking trains certain aspects of striking technique, for example, in punching, it trains you in maintaining proper hand shape, locking your wrist straight, and transferring the force of your mass into the target. However, breaking only trains you to break inanimate objects, which is not the same as hurting or injuring an animate object.
Answer to Question 1: Assuming all the concrete slabs are identical in size, consistency, and density, and there are spacers between the slabs (which means you are actually breaking each slab separately) then the same amount of force will be required to break each slab. This means that, in the breaking motion, you must maintain the amount of force needed to break the first slab as you hit each succeeding slab. When you are no longer able to maintain this force at a slab, it will not break.
Answer to Question 2: As stated above, breaking inanimate object is not the same striking a human body. You are not trying to injure boards, you are trying to break them; since boards do not feel pain, merely striking them accomplishes nothing. A strike that does not crack or weaken the board accomplishes nothing, other than teaching the striker a valuable session. Breaking boards, or slabs, requires you to bend them until their structural integrity fails and they break; striking a person can cause pain and devastating injury without breaking anything.
If you break a stack of eleven 2-inch thick slabs with quarter-inch high spacers between them (a total of about 24 inches high), it means you were able to maintain the amount of force required to break one slab over a 24-inch distance. It does not mean you were able to generate the amount of force required to break one 22-inch thick slab. If you could generate this much force, it would only need to be maintained for less than a one-inch distance.
Breaking eleven slabs with spacers between them means there were eleven separate impacts, each requiring a equal unit of impact force. Breaking one 22-inch slabs require one impact requiring approximately 11 times the impact force required in each impact of the stacked break. Since humans are one piece, not separate parts with spacers, striking a person with the stacked force impact would result in some injury and then push the person backward; while striking the person with the second impact force would cause massive injury but little backward movement.
As the old saying states, “boards don’t fight back.” You can take the time and effort required to punch through a board and you can throw your entire body into the technique since the board will not be avoiding, blocking, or counterattacking. If the break fails, you have time to regroup and prepare yourself for the next attempt. When the target fights back, such as when striking a human opponent, if you use the same striking technique you use to break boards when you attack the opponent, if the first attack fails, you will leave yourself vulnerable to counterattacks and may never get a opportunity to attack again.
If your watch boxing, you hear the commentators talking about how a fighter is losing the fight because he keeps “going for the knockout.” The fighter is concentrating on making powerful, follow-through, mass-committing punches, which take too much time and energy, usually miss the target, and leave the fighter vulnerable; while the opponent is using short, quick, snappy punches that hit their targets and cause pain and cumulative injury,
which usually leads to the fighter winning the fight.
Take the example of a side kick to the opponent’s midsection. If you try to kick through the person, there will be an initial impact force that does some damage, but any additional force is used to merely push the person backward, which causes little to no additional damage. If the kick is a snap kick that penetrates only a few inches, delivers its initial massive force, and then retracts before it has an opportunity to absorb the rebounding force from the target, then the target will receive the maximum force of kick, you will conserve energy, you will be able to regain your guard position quickly in case the kick misses it target and you are counterattacked, and you will be able to attack quickly again.
As a fighter, sometimes, you want an attack to push the opponent backward. For example, you may want to push the opponent into a range that permits you follow-up with a more powerful attack. However, pushing attacks should be avoided since they use up precious time and energy and may leave you vulnerable.