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In the Taekwon-Do Theory of Power, it is explained that the sine wave motion is used to add body weight to the movement, and then generates more power.

However, is there any evidence, viewed from scientific measurements that show by what proportion the power is increased?

do you have a link ?

Thanks :)

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    I should point out that critics of this theory show from Physics that the downward force can not contribute to the forward force. I would say that's too simplistic, since this is a human being, not a point force model. In a human being, the dropping motion can be translated into a wave through the body, as it travels to the legs. Then it bounces off of the ground and pushes upwards through the legs, where the force is then channeled out the arms. I don't know if this increases the actual force of the strike in a significant way than the non-sinusoidal way of striking does, however.
    – Steve Weigand
    Sep 30, 2015 at 20:17
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    Well I think what would make sense would be for someone to study punch power with and without sinusoidal motion. Because otherwise just looking at force vectors from a Physics standpoint isn't really going to get anyone anywhere (as I mentioned before, humans are not accurately portrayed by point force models). But the challenge of this sort of experiment is making sure the people being studied are really trying to give it their all in each case. And with TKD, maybe they don't really know how to punch well without the sine wave motion. Experimental methodology may be inadequate.
    – Steve Weigand
    Oct 1, 2015 at 10:33
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    @SteveWeigand: my branch of TKD split off before WTF/ITF had split, decades before sine wave, but from occasional training I've done with ITF folks and my own reading, I gather the movement involves a lowering of the body then an upward bounce and the punch or block being timed with the descent, so it's not a plyometric upward bounce into the strike as you describe. Personally, I see two reasons for sine wave: 1) it's unarguably not karate, so Choi finally could argue he'd created something new and distinct, 2) with Shotokan hip mechanics long lost, almost anything was an improvement.
    – Tony D
    Oct 1, 2015 at 13:15
  • For reference for how the "sine wave" is applied to TKD, there is an existing question: martialarts.stackexchange.com/q/1772/5961
    – mattm ♦
    Oct 1, 2015 at 13:35
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    @TonyD Yes, that's the non-politically correct version. Hehe. Thing is, I do see the possibility for the sine wave motion to work out for them, but they need some understanding of internal mechanics for that to happen. And you get that from studying Tai Chi and other internal arts. What I'm referring to is the "bounce jing" and "p'eng jing". The problem is that when they use the sine wave motion, they lose the connection with the ground and sort of "float" up high until they come down. Maybe that's better for TKD, since it involves so much kicking. But defensively it's not so good I think.
    – Steve Weigand
    Oct 1, 2015 at 19:33

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There are plenty of articles on the Internet (for example, http://www.saskgtf.com/theory.html) that talk about the 'science' of sine wave, but none of those articles appear to have any references to actual studies.

So, no evidence and no links, I'm afraid.

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    And indeed the formula for power on that website is wrong - it is an equation for energy, not power - which doesn't exactly inspire scientific confidence.
    – DNA
    Sep 30, 2015 at 21:03
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As Steve Weigand mentioned in the comments it is a very difficult task to objectively measure.

Having trained ITF for many years I would struggle to perform a punch powerfully without sine wave. It also takes a lot of practice to get the sine motion right. So to measure someone without sine wave and then teach them - they would have to train it. Some of the difference in power may be from the sine wave - but some of it may also be from training.

In the UK there is a big split between hip-twist and sine-wave groups. I have seen practitioners of both break multiple boards with ease. So whether you are training in sine wave or hip twist there is plenty of power to be found from YOUR body. Its about training hard under a good instructor.

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    Board breaking isn't a proper, objective measurement of power, though. So we'd need impact force measurements from some standard measurement device. (There are many out there, so you just need to select one and prepare a study.)... And that was a big caveat I mentioned. When you teach people how to punch both ways, you have to ask them to actually get good at both and really try to hit as hard as they can. You can gather many people together and look at averages. You can also look at people who just learned one and not the other. From these you might be able to glean something useful. Tricky.
    – Steve Weigand
    Oct 1, 2015 at 19:36
  • @SteveWeigandL "standard measurement device / many out there / just need to select one" - couldn't disagree more - my take on that here. Studies using half-baked measuring devices create more untrustworthy disinformation. Classic example of getting it wrong is that "fight science" BS from National Geographic.
    – Tony D
    Apr 28, 2017 at 19:44
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The upward downward motion of sine wave makes ITF practitioners very vulnerable to a Ju-Jitsu/Aikido/ninjitsu throw (the downward motion opens up 'O soto gari', and the upward motion would result in a devastating 'ippon'). The body movement makes them easy targets for a variety of throws. A static punch would be equally as effective, but reduces the options for a counter-attack throw.

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    That may or may not be true (I don't know), but the question is more about power, so this would be better posted as a comment rather than answer.
    – Tony D
    Apr 28, 2017 at 19:46
  • No responsive. Might be interesting if the theory were supported.
    – MCW
    May 1, 2017 at 1:18
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The most powerful punchers in the world are boxers. They do not seem to use sine wave; I've never really noticed Mike Tyson or George Foreman using sine wave.

MMA fighters who have experience in many martial arts, such as TKD, Karate, Muay-Thai, or boxing, do not seem to use sine wave, when it is all on the line (i.e. knock the other guy out while being at risk of being knocked out).

No doubt some will try to stretch the idea of stepping into a punch as sine wave, but it is not really sine wave in the context of what we are seeing in ITF TKD.

Observations based on reality are your best bet for a correct answer.

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  • sine wave is utilizing body weight dropping to increase the mass part of the force equation. Hip twist in ITF is about body rotation. Both of those come from natural movements (but are massively over exaggerated in the quest for power). So yes a normal step forward is natural sine wave (most straight attacks will be delivered with some sine wave naturally - some styles will just make/try to make far too much of it).
    – Collett89
    Oct 7, 2019 at 7:13
  • The question is not about the efficiency of sine wave for fighting. It is about the efficiency of sine wave for generating power. There could be many reasons not to use sine wave in fights that are not related to power generation.
    – Vakarm
    Apr 1, 2021 at 14:20

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