Cyclic hyperventilation involving 25 breaths greatly increases autonomic arousal and can deploy adrenaline.

“what happens if you do hyperventilation training well my lab studies cyclic hyperventilation is one of our many uh deliberate protocols and one of the most prominent things that one observes is that levels of adrenaline increase very quickly extremely quickly people feel jittery anxious stressed”

“Cyclic hyperventilation, as you recall, is a bout of 25 or so breaths inhaling deeply through the nose and then passively exhaling or sometimes actively exhaling, typically through the mouth.”