Contractions Schmontractions

Very weird day today. I did a pretty normal warmup, but just wasn't feeling right. On what I thought was the final warmup hold, I got contractions at 3:45 thinking I'm just not going to make it today. Then, out of the blue contractions at 4:45 and finally on the last try 5:15. What happened? I watched a video of Tom Sietas doing 8:56 and noticed that even a couple of minutes before the end, he starts to exhale slightly. So I started thinking, maybe there's a reason. Perhaps offloading co2 when the partial pressure is getting high in the lungs allows more of it to be offloaded from the blood and blowing out air at a late phase wouldn't matter, because most of the o2 that can be used from the air is already in the blood. Or something, I'm not a scientist so don't take this as a solid theory, but it sure feels better. Anyway, just when I started to feel the 1st contraction approaching, I exhaled a bit, very little, only a mouthfull or so. I kept doing this until finally I just couldn't block it anymore. But to my surprise, on the second try, I was well past 5 minutes. I don't know if the exhale is actually needed or if, like Eric F suggests, just "exhaling" with mouth closed, not actually letting any air escape, is enough. But I'll definently need to play around with this.

The thing is, I could only stand 20 contractions after that, so in total the time is about the same. But it sure makes the whole thing more comfortable and it must also have an effect on the absolute time, since the diaphragm must be consuming lots of energy with aggressive contractions. Anyway, reached 6:20 again, which gives me great confidence. And it was relatively easy too.

Empty lung 0:40
Empty lung 1:00
Empty lung 1:20
FRC 2:20
FRC 2:30
4:30 (5*5:0:5, 15 packs, 25 contractions, 1st 3:15)
4:00 (5*5:0:5, 15 packs, 28 contractions, 1st 2:50)
5:00 (10*5:0:5, 20 packs, 30 contractions, 1st 3:45)
5:40 (10*5:0:5, 25 packs, 20 contractions, 1st 4:45)
6:20 (12*5:0:5, 20 packs, 20 contractions, 1st 5:15)