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I think this is a good read:
Sanjay Doraiswamy
Some years ago, a kinesiologist named Sean Flanagan did a study on this and wrote an article in the Journal of Asian Martial Arts. The twist punch makes you significantly more prone to injury, is slower, and is not as powerful as a vertical punch. Amongst other things, he found that when the arm is loaded with forces from the fist, a twist punch puts a disproportionate amount of force on the ulna, which is the smaller bone.
Some people say that the twist adds power, but this idea is pseudoscience at best. First off, the rotation is perpendicular to the motion. Even if you could claim the twist adds power, the energy from the twist in a punch would be 12Iω2, where I=mr2.
According to Weighing in on individual body parts , the arm is about 6% of your body mass. If you weigh 100 kg, that's 6 kg. The radius of a MASSIVE bicep would be maybe 7 cm. (I have a 13" bicep, which would put my radius at maybe 5 cm.) Let's say your rotational velocity ω is about 4π/s, which I get from a half rotation in .25 s - quite generous values, I would say. This gives us a total added kinetic energy of
12(6 kg∗(.07 m)2)∗(4π
2s2=2.32 J.
Wow! So much energy! </sarcasm>
The next claim I've heard is that twist provides stabilization, similar to why bullets rotate when they are fired out of a gun. However, this is not possible at the slow speed of rotation - not anywhere close to the 3,000 RPS that a bullet might do. You can test out the stabilization yourself. Take a partner and try pushing on your arm in various directions, both with the arm extended and with the arm at post. You will find that the vertical punch is more stable (and hence more powerful and less injury-prone).
There are some other disadvantages as well:
Your elbow is exposed and quite vulnerable to an armbar/break.
Your opponent needs to be at the EXACT right distance; if he steps in, your wrist will get jammed.
The shoulder (for reasons I don't know, I'm not a kinesiologist) is typically not locked the right way, again making you more prone to injury (this goes back to what I said above about stabilization). This can be remedied by "squeezing a marble" under your armpit. The vertical punch automatically does this. Indeed, when Flanagan introduced the vertical punch over the twist punch in USMC boot camp, he documented a 20% decrease in shoulder injuries.
The twist punch is an unnatural movement; the vertical punch is similar to how we swing our arms when we walk.
The twist punch goes straight into the opponent's solar plexus; a vertical punch rises and therefore uses the opponent's weight against him. In addition, the solar plexus is more vulnerable against a rising punch. (You can try this; hold your fist right against a partner's solar plexus and "punch" him straight in, downward, and upward. You will find that the effect on your partner increases in that order, even though your "punch" had the same power every time.)
Sanjay Doraiswamy
Some years ago, a kinesiologist named Sean Flanagan did a study on this and wrote an article in the Journal of Asian Martial Arts. The twist punch makes you significantly more prone to injury, is slower, and is not as powerful as a vertical punch. Amongst other things, he found that when the arm is loaded with forces from the fist, a twist punch puts a disproportionate amount of force on the ulna, which is the smaller bone.
Some people say that the twist adds power, but this idea is pseudoscience at best. First off, the rotation is perpendicular to the motion. Even if you could claim the twist adds power, the energy from the twist in a punch would be 12Iω2, where I=mr2.
According to Weighing in on individual body parts , the arm is about 6% of your body mass. If you weigh 100 kg, that's 6 kg. The radius of a MASSIVE bicep would be maybe 7 cm. (I have a 13" bicep, which would put my radius at maybe 5 cm.) Let's say your rotational velocity ω is about 4π/s, which I get from a half rotation in .25 s - quite generous values, I would say. This gives us a total added kinetic energy of
12(6 kg∗(.07 m)2)∗(4π
2s2=2.32 J. Wow! So much energy! </sarcasm>
The next claim I've heard is that twist provides stabilization, similar to why bullets rotate when they are fired out of a gun. However, this is not possible at the slow speed of rotation - not anywhere close to the 3,000 RPS that a bullet might do. You can test out the stabilization yourself. Take a partner and try pushing on your arm in various directions, both with the arm extended and with the arm at post. You will find that the vertical punch is more stable (and hence more powerful and less injury-prone).
There are some other disadvantages as well:
Your elbow is exposed and quite vulnerable to an armbar/break.
Your opponent needs to be at the EXACT right distance; if he steps in, your wrist will get jammed.
The shoulder (for reasons I don't know, I'm not a kinesiologist) is typically not locked the right way, again making you more prone to injury (this goes back to what I said above about stabilization). This can be remedied by "squeezing a marble" under your armpit. The vertical punch automatically does this. Indeed, when Flanagan introduced the vertical punch over the twist punch in USMC boot camp, he documented a 20% decrease in shoulder injuries.
The twist punch is an unnatural movement; the vertical punch is similar to how we swing our arms when we walk.
The twist punch goes straight into the opponent's solar plexus; a vertical punch rises and therefore uses the opponent's weight against him. In addition, the solar plexus is more vulnerable against a rising punch. (You can try this; hold your fist right against a partner's solar plexus and "punch" him straight in, downward, and upward. You will find that the effect on your partner increases in that order, even though your "punch" had the same power every time.)
