Merudanda mudra can be used in meditation. It centers and calms the mind and quiets the breath.
The first position wth the thumbs pointing toward each other is called adho merudanda mudra. It helps to relieve pain in the low back. The next gesture with thumbs pointing upward is called merudanda mudra and helps to straighten the back and relieve pain in the middle of the back. The last one with thumbs pointing away from each other is called urdhva merudanda mudra and helps with pain in the upper back.
The merudanda mudra sequence is great for improving the awareness and the experience of directing the breath to different parts of the body. It teaches to notice the movement of the breath, its quality and origin during the sequence.