Eka Padasana follows Urdva Prasaritha Eka Pada Uttasana (or "upward-split-one-leg-stretch-position"); it is the fourth position in the Prana Vashya Yoga™ sun salutation. Eka Padasana translates as "one-leg-position".
How to get into the position
Starting, then, with one leg raised in Urdva Prasaritha Eka Pada Uttasana, you should hold your breath, step back with the same leg that was raised in Urdva Prasaritha Eka Pada Uttasana, and place knee on the floor. To complete the position you then free the hip by un-tucking the toes so the foot is flat to the floor before tucking the toes back under again (in readiness for the next position in the sun salutation). The centre of gravity is on the thigh; hence the name for this pose: Eka Padasana or "one-leg-position".
Pay attention to the position of your forward knee in Eka Padasana; do not let your knee go in front of your ankle. This is important because otherwise the thigh is not engaged, and your will end up straining your knee and/or groin.
If you cannot square your hips with your palms flat on the floor in this position, then come up on your finger-tips; it is important to keep the hips square for good posture.
This pose stretches the thighs, groin, ankles, knees, and feet.
It also improves posture and tones the pelvic muscles.
Avoid this asana if you have any issues with your lower back, ankle(s), or knee(s).