I finally got around to trying apnea walking that everyone's been
doing. The track I used was from my garage down to the street and
back. That's 340' round trip. It started getting a little
uncomfortable 3/4 of the way through it. Think I counted 120 paces.
You can really feel the lactic acid in the legs the last few seconds.
It took about 1:10. The second time I tried it was easier. I had just
finished a 10 mile run an hour before, so don't know if that helped
or hurt.
By the way, I got my wife to bring home the portable pulse
oximeter from her nursing agency, and noticed interesting results.
Saturday the reading kept a steady 100% blood oxygen saturation, even
with shallow breathing. I want to note that the last 10 mile run was
2 days prior. Doing some statics, it took 3 minutes for the 02
saturation to even start dropping below 99 or 98%, even when
the "struggle phase" began. It seemed to really avalanche fast toward
the end, and my wife confirmed this is typical from charts she has
observed. I could not hold my breath below 72% saturation. I want to
mention how fast it began dropping. Once it dropped into the 80's,
the rate of decay was about 1% for each heartbeat, which happened to
be about 38 beats per minute at the end. The interesting thing was
that once I started breathing again, the reading kept dropping for a
few more seconds, then began climbing extremely fast, and the last
few percent (between 98-100%) took a few seconds longer, fully
recovering to 100% in about 45 seconds. The need for a longer
breathup must be to purge C02 trapped in the tissues and fat. (It is
claimed that fat tissue retains C02 and nitrogen 6 times longer that
other tissues). If I only had a method of measuring residual C02, it
would prove the other piece of the puzzle.
Day 2 (Sunday): Tested my 02 Sat. an hour after finishing a 10
mile run and washing the car. Could not get a "normal breathing"
reading of over 96-97%. This continued all day, although I could
breathe-up and force it to 100%. Note the day before, shallow
breathing yielded 100% all day. This reduction may have been
to electrolyte and mineral losses from a stressfull workout at 90% of
maximum heart rate, or maybe the apnea walking I performed that day.
This morning (monday) I still did not get a "normal breathing"
02 reading of over 98-99%. It seems apnea and hard workouts carry
over into the next day. I've suspected this from times that I dove
consecutive days at Dutch. The bottom times are never as good on the
second day of diving as the first day.
In conclusion, I suspect that the discomfort at the onset of the
struggle phase (that still indicated a 98% saturation), may be due to
C02 tolerance being low and not really low 02 at all. We all know how
practice can raise C02 tolerance, and now realize that practice will
improve that aspect. I haven't really practiced statics this year
like last year, so the C02 tolerance is probably lower than it used
to be.
Now if someone would develope a dive computer that has the finger
sensor attached (or wireless) to wear under the glove. That would be
the ideal diver "fuel gauge" that surely would prove usefull.
Especially if incorporated with an audible alarm, set to say 85 or
90% oxygen saturation.
Sorry for the long post, but the tests were long too, and I
felt I had to share them, so we gather a better understanding of our
physiology and our sport.
More tests to come someday,