A Supporting Block (also called an Augmented Block, an Assisting Block, or geodeureo makgi) is a block in which the off-hand is held in front of the sternum, usually palm-up. The wrist of the supporting hand should be immediately in front of the sternum.
Usually, the idea of an Augmented Block is that the augmenting hand is now chambered for a short strike that might follow the block. For some types of augmented blocks though, the augmenting hand touches the blocking arm to literally provide extra push to the block.
In Kukkiwon/WTF-style taekwondo, the blocking arm is usually chambered fist-up at the ribs (i.e., palm facing up), while the augmenting arm is chambered out to the side, with the palm turned away from the body. That allows the blocking arm and the augmenting arm to rotate during the block.
If the outward block is performed with the inner-forearm, the chamber for the blocking arm is fist-down (i.e., palm facing down) at the waist.
- When the augmented block is performed with knife hands, it is a Double Knifehand Block, also called an Augmented Knifehand Outward Block.
- When the blocking arm is a Low Block rather than an Outside Block, the block is an Augmented Low Block.
- Blocking on the Kukkiwon website