Taekwondo Reaction HandPull back hand. The reaction hand. The fist chambered at your side. (Japanese 'Hikite')
When performing a front lunge punch, the pull back or reaction hand of the opposite arm is drawn directly back towards the side of the body. It should not be snapped downward to the hip but should more so be pulled back towards the side of the ribs. If you perform a shuto, the reaction hand floats in front of your solar plexus when you present one side of your body forward. In a punching scenario, the pull back hand is at the level of the shuto pull back position.
The pull back motion is accredited with being able to perform an elbow 'backwards' to an opponent standing beside you. This is not the primary reason why the pull back motion exists in a hard style martial art. The reaction hand is a tactical move to hold an opponent still (to be struck with other hand), creates a great deal of shearing force (when trying to break opponent's joint or when performing a throw), and allows a practitioner to learn proper upper body tension in order to transmit the power of your legs and hips into strikes levelled on your opponent.
To create such a force, both hands must work in unison to create a balanced tensional force in the upper body. The pull back hand or hikite tightens the shoulders and helps link the upper body to the torso.
Many beginners get confused with the pullback hand especially during self defence or sparring. One of the most important things in sparring is to provide defence and coverage to the body. Pulling the hand back to the hip creates a void between yourself and your opponent - allowing openings that your opponent can take advantage of.
The pull back motion should be used in such a scenario when you attempt to pull or hold onto your opponent whilst hitting him with the other hand. Or if you intend to break his arm - meaning you hold onto the limb while striking it perpendicularly. Otherwise, the hikite need not be positionally pulled back to the hip UNLESS your opponent is not going to hit you with either of his two weapons.
The other major mistake beginners do is that the pull back hand does not work in synchronicity with the striking (or blocking) hand. Without both hands working together - crossing over, spreading apart, forward-backward ... there cannot be dynamic fluid nor reiterative movement. Meaning your upper body techniques whether you do karate or traditional taekwondo or whatever will suck. Or at most you'll be able to get off one strike or block while the opponent peppers you with several strikes.
To end off, the hikite should be performed as hard as the striking or blocking technique going out, the elbow should be held tightly to your body, and the pull back hand should be at least on the floating ribs or a little higher. The application of the pull back hand should be a lesson in point for the beginner that the theory as taught in basics are not always a facsimile for 'real' combat - and that the beginner should look for the 'takeaway lesson' of the hikite, rather than focus on pulling one of your defences back onto your hip.
For a continuation of this post, please see the discussion I've had on Traditional Taekwondo Ramblings Taekwondo Punch v Boxing Punch.
Check out related posts:
Dangun Reaction Hand
Chon-ji Lower Block Against a Kick
Lower Block Beginner Drill
Karate Thoughts Blog
FightingArts.com - Chambering
Ikigai: Hikite - The Withdrawing Hand