Bahl Deung Cha Ki is the staple kick of all kick-oriented martial arts. From offensive or defensive stance, either the lead or trailing leg can execute this kick. I will describe it from the rear leg, which is a more powerful kick than when executed with the lead leg. The student should first bring their knee up while rotating the hips fully. At the same time, the foot the student is standing on needs to pivot on the ground until the toes are pointing at least 90°, and up to 180°, from the attack vector*. When chambered, before actually kicking, the knee should be on its side and the hips completely open. The leg is then extended, and the striking surface is the instep of the foot. It is important to rechamber the kick before returning to stance. The rotation of the hips should complete at the exact moment the leg reaches full extension to deliver maximum force. As will all bent-legged kicks, it is important to avoid "snapping" the kick, which causes damage to the knee. Hold the kick at full extention for at least a second before rechambering and returning to stance.
In Muy Thai and American Kickboxing, this kick is performed differently. The hip is opened up at the very begining of the kick, and the the leg swings on the outside into its target. While this is powerful, it is easily read by your opponent and more easily blocked than the Korean style Bahl Deung Cha Ki, which masks its target until the last moment, and cannot be blocked until the leg is ultimately extended. Bahl Deung Cha Ki also lends itself to a fake or double kick, where after chambering, the kick is delivered low and then high in quick succession. This is not possible in the Muy Thai or American Kickboxing version of the kick, which is another of the reasons it is considered inferior to the Korean version.
- Attack Vector - the imaginary line bisecting the heel of the back leg and the foot of the front leg, pointing in the direction of your opponent. In sparring, maintaing an awareness of this line allows the student to better position himself in relation to his opponent.