Just saw this post, and it's a very good subject, and timely too...

By "normal" ways, I guess you mean "natural", right?

One's hematocrit is pretty much genetically determined, with a few factors thrown in. The main one is altitude (oxygen tension, or partial pressure). The kidneys have "sensors" that measure O2 availability. Anything that lowers the level of oxygen in the blood, or it's ability to be used by tissues, will stimulate Epo production and the corresponding rise in hematocrit...or more accurately, red cell mass. Hematocrit can be temporarily affected by changes in plasma volume, but red cell mass cannot.

Things that lower 02 delivery, that I can think of, are: increased altitude (or lower 02 levels), and carbon monoxide exposure. Yes, smoking (a lot) will raise the hematocrit since CO renders the red cells (or more specifically hemoglobin in the red cells) unable to carry 02 correctly.

In short, the hematocrit is pretty much fixed genetically and individually, depending on a few environmental factors. This of course, is assuming the individual is not deficient in anything needed to actually make red cells, such as vitamins and iron. And: No, taking extra iron or vitamins will not raise the HCT past the set point.

I am interested in finding out how hard aerobic training affects the Hct. And when I say Hct, I mean Epo levels. I don't think it does, but I am not an expert in sports physiology so I can't say at this point. I also wonder if oxygen debt/anaerobic training will have any affect on Epo levels. I will do some research and see what I can dig up.