Hi, just my humble contributions.
Motivated by this thread I've been doing similar experiments for a week or so. Anyway, I've never experienced ringing ears before, but in the past couple of days I get it every time. The difference is, that I've changed from "hyperventilation and full static" to no ventilation and timing only the part after 1st contraction. The statics I've done these few days can't have been more than 4-5 minutes (don't know actual time, since I don't time them), but still I get ringing ears and a slight headache from each trial and I get really warm, hot even. So at least in my part, I'd say the ringing definately comes from co2. This feeling passes within a few breaths after the hold.
It also seems that I always peak on the second try for maximizing the time of contractions. But my first hold is getting closer all the time, so maybe some day I only need one. We'll see...
One thing I've noticed is that with this kind of training, relaxation becomes easier. I think I sort of got "there" a couple of times, where after some 40 contractions, where I would usually bail, I just sort of fell into my mind and surfed them, reaching 100 for the first time today
I'm pretty anxious to get to try this in the water tomorrow for the first time.
On a side note, according my girlfriend I actually packed in my sleep last night. That's kind of freaky
I was dreaming I was in a competition getting ready for a start...Sheesh. Gives whole new meaning to sleep apnea though
