Do not beat the buttocks too hard on the floor; if you do then you may injure yourself. Do not let the coccyx bone (tailbone at the bottom of the spine) land directly on the floor. The buttocks and the back of the folded legs should hit the floor at the same time. This will cushion and distribute the force of the fall over a wider area.
Inhalation and exhalation should be done with ujjayi. Inhale while drawing prana down to mooladhara (figure 1). Hold the breath while beating the buttocks (figure 2). Exhale while feeling the diffusion of prana from mooladhara (figure 3). If you wish you can breathe in and out once between each round.
You should be aware of breath, eyebrow centre (in shambhavi mudra), physical movement and the accumulation and diffusion of prana at the mooladhara chakra.
Number of beatings
You have to hold your breath while beating the buttocks. Beginners should beat their buttocks only 3 times. Add 1 more beating every few days to a maximum of 11 full beatings.
The practice takes about 1 minute per round. Therefore, the complete duration is about 7 minutes.
Tadan kriya should be done after manduki mudra and before naumukhi.