I specifically practice this method. The basic protocol is 4 rounds of 40–45 breaths, with a 3-minute hold after the last round. The longest hold was during the intensive protocols of 6–8 rounds: 3 min. 45 sec. I do not force it (when I want to breathe in, I do so; with this method, you must not hold your breath by force) — “small forces create, medium forces slow things down, great forces destroy.” In icy water for 7–10 minutes. Everything is fine. I first learned about Wim from the “Your Yoga” website. Great thanks to Sergey Vasilyevich for this!
1st cycle, 15 breaths, hold 40 sec.
2nd cycle, 15 breaths, hold 45 sec.
3rd cycle, 15 breaths, hold 60 sec.
1st cycle, 15 breaths, hold 50 sec.
2nd cycle, 15 breaths, hold 50 sec.
3rd cycle, 15 breaths, hold 60 sec.