My first attempt to hold my breath as long as possible ended at 1:16 about two months ago. Since then I was practicing 2-3 times a week with an iOS app (Apnea Trainer) and could improve my breath hold to more than 5 minutes. This video shows my best try so far. I also measured my heart rate and my blood oxygen level (SpO2), which dropped to scary 52%.
This is not a tutorial, it's just my way of breath holding. I'm a beginner freediver and there is a lot to improve. For example all the movement due to showing SpO2 and checking the stopwatch ;-)
If you're bored to watch the full video just seeing a guy lying there trying not to breathe, here are some markers to jump to key scenes:
00:29 end of breath up with last total lung fill
00:33 starting apnea time and trying to relax
01:19 trying to find a more relaxed position
02:50 leaving comfort phase with small contractions starting
03:50 diaphragm contractions getting stronger
05:15 blood oxygen saturation dropping quickly from 70% to 54%
05:48 last seconds fighting
06:04 ending apnea time, breathing heavily
06:51 blood saturation raising quickly from 52% to 98% within seconds
06:57 table of record attempts so far
