Under scientific point of view, there are too many factors in the darkness when we speak about systems for enhancing the performances.
We have some DIRECT proof about the effects of some doping : for example, it's acclarated that with EPO and similars we can raise the level of Hb anf Hct.
But the reason because some athlete is able to improve his times till the top of the world, is not in the level of Hb and Hct.
We have too many components, which works together, and for some component able to produce advantages we have other components producing some disandvantage.
At the end, the performance is the product of a balance within bioenergetic and metabolic system, neuroendocrinal system, biomechanics, mental level, motivation and enviroment.
I like somebody asking a different question : "Taking EPO, which are the problems we go to create in the body" ? Because of sure when we introduce some pharmac in our body there is some activity of compensation, since we go to change the Equilibrium between several components.
One, for example, is the increase of viscosity.
But we can reduce the viscosity using some pharmac able to dilue the blood.
Which is the reaction of the body to this new pharmac ?
And, if we can increase the total blood volume in the body of some athlete of top level during 3-4 months of tough aerobic training (about 1 and half liter more), the same thing can happen also if the athletes take EPO ?
And, in this case, when he has to take EPO ? At the beginning of his training (but in this case the blood density becomes higher, and he can't be able to produce this 1 and half liter of blood more), or at the end, when he can already have this 1 and half liter of more blood in his body ?
And somebody can understand the difference between the REACTION of the body for a new stimulus (the case of athletes going from sea level to altitude), producing, not Always, but in 80% of cases, some increase in the number of reticolocytes (medulla is stimulated to produce new cells), and the ADAPTATIONS of people born and living and training in the same conditions ?
So, if for athletes going altitude we can speak about an ANSWER to some new stimulus, for athletes living and training in those conditions which is the advantage ?
With EPO we can increase the ability to transport Oxygen. But, before thinking to transport some material, we must have the material, and we can see a big difference in the affinity between Hb and Oxygen, among top athletes of altitude, and athletes at sea level.
So, the athletes living and training in altitude develop a higher affinity, in order to have in altitude the same quantity of Oxygen the other have at sea level, and, of course, when they go sea level for some competition, they can have MORE OXYGEN than the athletes of sea level, because their system was able to develop the ability to catch the gas from the air.
The velocity of blood circulation is the same for arterial blood, transporting oxygen and "fuel" to muscle fibers, and venous blood, which carries deoxygenated blood for tissues back to the heart, but when we are able to increase the velocity of circulation we are also able to remove the effects of "rubbish" produced by the activity in the fibers faster, and if we reduce the velocity of circulation because of higher viscosity, we reduce also the velocity of elimination of the products of fatigue.
We have really too many points to discuss, which in many cases depends on individual factors, for having a certainty in one direction or in the other.
So, while I'm sure EPO can help the most part of athletes to increase their PB, I continue to think that can't enhance the performances for the very small category of athletes with the following requirements :
1) Born, living and training in altitude
2) Having top talent
3) Using an advanced smart and hard training
4) With full focus in athletic
5) With max level of self confidence in their "natural" possibility
But these are the qualities for being Champions, and this is the reason because I strongly believe ALL the athletes in this category are clean.