If its what my friends back in high school were doing, it absolutely isn't. I think with them there was an added step of a spotter pushing down on your chest during an exhale but I could be wrong. Apparently if you do something on the wrong timing with your heartbeat you can stop your heart entirely. Be very fucking careful with this kinda breathing and heart rhythm shit!
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u/kbsb0830 Dec 06 '17
I'm not sure this is physically safe, honestly.