Uddiyana Bandha: technique

Uddiyana bandha and https://www.julianalucky.com/post/mommy-and-me-yoga-benefits is performed by pulling up the front of the lumbar spine, pulling the navel back into the spine and up into the diaphragm.

Uddiyana bandha is performed standing, sitting, or lying down. At the initial stage, you should first master the performance from a standing position.

Note that this technique is performed strictly on an empty stomach, and preferably also on an empty bowel.

Consider the technique of doing uddiyana bandha from a standing position:

Stand up straight, with your feet a little more than pelvic width apart.
The feet should be firmly rooted, with the heels pressing into the floor.
Take a full deep breath.
As you exhale, lean forward with your back straight.
Bending your legs at the knees, rest your arms, straightened at the elbows, on your hips (allowing your chest to expand). With your shoulders pulled up to your ears, place your palms on your feet above your knees on the inside of your hips, with your thumbs pointing inward.
Perform Jalandhara bandha, pulling the chin up to the sternum without straining the neck.
Draw your stomach in, keeping it relaxed, allowing it to pull up freely to the diaphragm. When you exhale very hard, your lungs empty and press against the top of your chest, pulling your diaphragm up behind you as well. As the empty space appears, the bowels move upward. In this movement, which your belly normally goes through when you inhale, there is what is called a false breath, but in fact there is no inhalation through your nose or mouth.
Extend the sides of your lower back, iliopsoas muscle.
There should be a sensation that internal organs rise up.
Linger in this position.
Finish the bandha with a deep long inhale: lower your belly down and smoothly return it to the natural, relaxed position, release the throat lock, only after that you can inhale, gently and without effort.
Relax into Balasana.
The technique of performing Uddiyana bandha is similar in the sitting position with your back straight and your legs crossed. With your palms on your knees, your arms are straight.