Hae Sul 4: Gae-Baek elbow lock takedown

12-22-2017: This post has gone through some rewrites. I now interpret the arc hand block followed by the upset punch as creating a wrist lock.

So much for the first double arc hand block in Gae-Baek. Now for the second.

Movements 25-28 of Gae-Baek can be used to create a couple wrist and arm locks. The double arc hand "block" can used to set up an S-lock, also called a Z-lock or nikkyo. The way this lock works is similar to the standing armbar (ikkyo). Both require you to pronate the opponent's arm, but whereas in the armbar the opponent's arm is straight, in the S-lock the opponent's elbow is bent. As you bend and force the opponent's wrist towards their body, this forces their elbow upwards. So all you have to do to complete the lock is prevent the opponent's elbow from rising up.

Sources: coshigould, Black Belt Magazine

The reaction hand for the upset punch pulls down the opponent's elbow while the upset punch bends their wrist in towards their body. This creates the lock. Applied literally, the movements create a Z-lock against a cross hand grab. But with minor modification you can create the lock against a same-side wrist grab as well.

There are other ways to apply the Z-lock. Rather than directly hooking the elbow with your second arc hand, you could trap the opponent's hand as you twist their wrist.

Another way of applying the S-lock. Source: ExpertVillage

Notice that in the form, we are creating the lock on the opponent's left arm. If the lock fails, we can then use move 27 (180-degree turn into horizontal elbow strike) to follow with waki gatame (also called hiji kime osae in Aikido). This lock is functionally similar to the S-lock and standard armbar. It involves pronating the opponent's arm while placing your elbow on top of theirs, locking their arm. The supporting hand pushes the opponent's hand in towards their body, getting a secondary wrist lock. From here, we can use the "leap" into the double forearm block as a takedown.

Movements 27-28 as an armlock followed by a takedown. Note that in the example the tori controls the right arm, whereas in the form we control the left arm.
Source: Budo Shingikan School, coushigould

"Leap" is in quotes because a literal leap is not necessary (although that would be a quick-and-dirty takedown). Look at the variation from Hapkidoin Alain Burrese below. Rather than leaning forward onto his opponent, he leans backwards and sits down, forcing his opponent to the ground with him.

Source: Your Warrior's Edge

Although it's not a leap, you can still see the use of the double forearm block, bending both the wrist and arm in towards the opponent's body.

Because both of these techniques follow from a wrist grab attack, the preceding move in the form -- the twin vertical face punch -- may be used as an initial strike: a quick pop to the face if an opponent grabs your wrist.