BumDoh (Bum:general, Doh:step)
SoDoh (So:small, Doh:step)
Beginners may benefit from holding the BumDoh and SoDoh positions (placing all weight on one leg) for as briefly as 30 seconds. As the inner force of the leg improves, the positions should be sustained for at least 5 minutes.
The powerful central abdomen formed by NaeGa ShinJang will be strengthened and expanded to the left and right sides with BumDoh & SoDoh.
BumDoh and SoDoh are especially effective in improving Gi flow in two channels located in the legs: JokSoYang DamGyeongRak (Jok:foot, SoYang:bright, Dam:gall bladder) GyeongRak, one of Gi channels which runs between the foot and gall bladder; and JokYangMyeong Wi (Jok:foot, YangMyeong:shining, Wi:stomach) GyeongRak - one of Gi channels which runs between the foot and stomach.
As with NaeGa ShinJang, the key functions of this position are natural abdominal breathing and YeokGeun (Yeok:changing, Geun:muscle). YeokGeun changes the muscles and ligaments of the body that tend to lose flexibility and elasticity and eventually become stiff and weak. DaeDoh brings about YeokGeun of the muscles surrounding the spine, greatly improving the flow of Gi throughout the body.
GeumGye resembles the one-legged stance of the long-lived crane, and is held to be conducive to longevity. Maintaining the balance of the body with one leg heightens the sense of equilibrium. It intensifies the inner force of the lower abdomen, which facilitates the smooth movements of the stomach and small and large intestines.
This is the most difficult position for beginners, who usually cannot hold it for more than a few seconds. It requires great flexibility and power of the waist, and also the most fully stretched leg. HurGong helps the Gi circulate throughout the arms and legs by expanding and stretching the waist and legs to the utmost degree.
See also DahnBaeGong pictorial (images 1, 2, 2-1, & 3-1; Sentences (1), (2), & (3).