Pada means the foot. Angustha is the big toe. This posture is done by
standing and catching the big toes.

Technique

Stand in Tadasana. Spread the legs a foot apart.

Exhale, bend forward and hold the big toes between the thumbs
and the first two fingers, so that the palms face each other. Hold them
tight.

Keep the head up, stretch the diaphragm towards the chest and
make the back as concave as possible. Instead of stretching down
from the shoulders, bend forward from the pelvic region to get the
concave shape of the back from the coccyx.

Keep the legs stiff and do not slacken the grip at the knees and
toes. Stretch the shoulder-blades also. Take one or two breaths in
this position.

Now exhale, and bring the head in between the knees by tightening the knees and pulling the toes without lifting them off the floor. Remain in this pose for about 20 seconds, maintaining normal breathing.

Inhale, come to position 2 release the toes and stand up.
Return to Tadaasana.