Foot Fist Way: Hae Sul 1: Dan-Gun rotary throw

I've decided to try a different format for these posts. Rather than long, encyclopedic explanations of forms, I'm going to focus on single sets at a time. This will hopefully make things more digestible. For the inaugural post, let's return to Dan-Gun.

The twin outer-forearm block has changed between karate and ITF taekwondo. In both karate and kukki-taekwondo the front fist faces inward. This works well for one of it's main applications: a simultaneously rising block and strike to the jaw. The chamber is also down at the hips, meaning both arms travel upwards.

Twin block from Choi's 1965 book

Oddly, ITF taekwondo made two changes to the movement, and not at the same time. By the time Choi's 1965 book Taekwon-do: The Korean Art of Self-Defense was published, the front fist faced outward, but the trajectory of the technique was the same as in karate (right image). By the time the Encyclopedia of Taekwon-do was published 20 years later, the chamber had altered into the cross-arm setup we practice today.

Because of these two changes, the applications differ from the karate version. The orientation suggests that both hands could be grasping something. Take a look at this shoulder lock from an old Judo self-defense manual.

Source: Art of Manliness.
Originally from Modern Judo and Self-Defense by Harry Erwin

In case you can't see it, the back hand rising "block" is used to lift and turn the opponent's arm, while the front hand grabs the opponent's shoulder, pinning them. Even the initial defense looks like the low chamber from Choi's 1965 book. A common variant is to grab the head rather than the shoulder. Although the defender uses a 180-degree turn, often a three-quarters turn makes this lock easier. This brings us to Dan-Gun. The set we'll analyze is:

Front stance high punch
Front stance high punch
Three-quarters turn into back stance twin outer-forearm block, sliding the back leg
Front stance high punch

An application for the first three movements are shown in the gif by two Krav Maga instructors below:

Source: Stewart McGill

Details:

Use the setup hand to parry a round punch as you enter and thrust your elbow over your opponent's shoulder (first high punch). Make sure you grab and pull your opponent's arm with the reaction hand
Take another step forward, raising the opponent's arm while you pull down their shoulder (second high punch)
Continue by stepping out with your back leg and doing a three-quarters turn into the twin outer-forearm block, raising their arm and pinning their shoulder or head. This twists the opponent's arm behind their back, putting them into a shoulder lock.

Although the example gif above is against a round punch, I've also seen Krav Maga instructors use this technique against a blunt weapon -- like a bottle or club -- similar to the Judo knife defense above. Twisting the opponent's arm back in this way makes it difficult for them to hold onto their weapon.

The Rotary Throw

You have a few options from this position. You could knee strike your opponent, attempt to pin them, or you can do what in Aikido is called a kaiten nage, or "rotary throw." The latter is what the form recommends, with the final high punch.

Source: Rogue Warriors

As you walk forward into front stance, use the opponent's own arm as a lever to throw their body (remember: they are in a shoulder lock). You can also use your reaction hand to press down their head so they are forced to flip over.

There are a lot of online tutorials on this throw if you're interested in more detail. Just be warned that the entry for aikidoka is very different -- they don't really defend against punches -- but the throw itself works.