Psychophysiological Effects of Controlled Respiration and Mindfulness

Participants are informed they should sit down in a chair or, if they preferred, to lie down, and then to set a timer for 5 minutes. Then they are told to close their eyes and to start breathing while focusing their mental attention on their forehead region between their two eyes. They are told that if their focus drifted from that location to re-recenter their attention by focusing back first on their breath and then on the forehead region between their eyes. They are told that as thoughts arise, to recognize that as normal, refocus their attention back to their forehead region and to continue the practice until time has elapsed.

Participants are informed they should sit down in a chair or, if they prefer, to lie down, and to set a timer for 5 minutes. Then they are told to inhale slowly, and that once their lungs are expanded, to inhale again once more to maximally fill their lungs -- even if the second inhale was shorter in duration and smaller in volume than the first, and then to slowly and fully exhale all their breath. They are told to repeat this pattern of breathing for 5 minutes. They are also informed that ideally, both inhales would be performed via their nose and the exhale would be performed via their mouth, but that if they preferred, they are welcome to do the breathing entirely through their nose. They are also informed that it is normal for the second inhale to be briefer than the first.

"Participants are informed they should sit down in a chair or lie down, and to get a timer. Then they are told to take the CO2 tolerance test as follows: Take 4 breaths through the nose. Then take a maximally deep breath and once your lungs are full, exhale as slowly as possible through your nose or mouth. Time how long it takes to empty your lungs; this will be your C02 discard duration. Use your discard duration to determine how long your inhales, exhales, and breath holds should be (CO2 discard time) by using this table: \<20 sec = 3 - 4 sec, 25 - 45 sec = 5 - 6 sec, 50 - 75+ sec = 8 -10 sec. They are then told to inhale, hold, exhale, hold (for the duration determined by the C02 discard table) and to repeat this pattern for the entire 5 minutes. If at any point they had to strain to reach these times, they should simply reduce the duration of inhales, exhales, and breath holds. We ask participants to perform all breathing through their nose, if possible."

"Participants are informed they should sit down in a chair or, if they prefer, to lie down, and to set a timer for 5 min. Then they are told to inhale deeply (ideally through their nose but if that is not possible, to inhale through their mouth) and then exhale by passively letting the air fall out from the mouth. We inform them that for sake of this protocol, that pattern of a deep inhale through the nose and passively letting the air fall out from the mouth = 1 breath.~Then they are instructed to perform 30 breaths (in and out) in this manner, and after those 30 breaths, to exhale all their air via their mouth and to calmly wait with lungs empty for 15 seconds."