Loppas, if you have time, can go to read all the scientific articles posted in a previews post.
You can see that all the researches had the following subjects :
* Athletes living high and training low
* Athletes living and training at sea level, with periods of altitude of limited duration (max 4 weeks)
* Athletes living and training in altitude after moving sea level for few days only
The normal category of African runners is : Athletes living high and training high, with adaptation to altitude, for them a nomal condition.
In all these studies, NEVER we found a quantification of the performances of the athlete, and the detail of the purposed training.
In all these studies, NEVER there is the evaluation of the effects of training (how for the researchers training didn't exist).
The following words are from the article "The Influence of Training Load on Hematological Athlete BP variables in Elite Cyclists" :
Our results support that acute training load variations significantly affect (Hb), likely due to short-term PV fluctuations, underlining the importance of considering training load when interpreting individual ABP variations for anti-doping purposes.
Also if the human machine works the same way in different individuals under physiological point of view, IT'S THE LEVEL OF TRAINING (both volume and intensity) WHICH PRODUCES VARIATIONS IN HEMATOLOGICAL VALUES.
All the studies regarded a duration of maximum 40 days. We know that the most talented athletes of endurance can increase their total volume of blood till 25%, but this process has to last 3-4 months, the time occurring for reaching the max personal levels of training without going in overtraining. This means that, from the beginning of the period of hard and proper training, THE HEMATOCRYT OF THE ATHLETE GOES DOWN, AND THE NUMBER OF RBC DECREASES, WHILE THEIR VOLUME INCREASES IN THE PLASMATIC PART.
This means, also, that with the increasing of a NATURAL TRAINING there is a period (coinciding with the best shape) where the blood has the lowest viscosity, and this can help the velocity of circulation.
This is the reason because I continue to think EPO is useless, if talented athletes (not necessary African) have patience and continuity for growing WITH TRAINING ONLY till their physiological limit, and in this case NOTHING can be added to their shape in order to improve the performances.
But, of course, researchers (biologists, physiologists, chemists...) know about training methodology (systems, limits and goals) exactly like LetsRun posters : NOTHING.