Witnesses watched through a window at an Alabama prison as Kenneth Eugene Smith became the nation's first person to be put to death using nitrogen gas.
Beyond the burning in your lungs, the signals your body gets from your brain when your C02 levels are too high, include strong, painful, and involuntary contractions or spasms of the diaphragm and the muscles in between your ribs. At some point the spasms become so frequent and unbearable that you can no longer hold your breath.
Spasms for holding your breath? Uh, no?
Give it a try while recording yourself. Don’t worry, you won’t die. Just have someone with you while doing it, for safety reasons.
https://www.scq.ubc.ca/waiting-to-inhale-why-it-hurts-to-hold-your-breath/
Beyond the burning in your lungs, the signals your body gets from your brain when your C02 levels are too high, include strong, painful, and involuntary contractions or spasms of the diaphragm and the muscles in between your ribs. At some point the spasms become so frequent and unbearable that you can no longer hold your breath.