Aragon, for understanding the validity of the studies you mentioned, we need to know some particular, that NEVER are clear in ANY research.
For example, when they speak about "performance" for the tested Group, what exactly this performance is ? Is something on teadmill lasting 5 or 10 minutes at max intensity, is an incremental test, or is a Marathon ?
And which is the level of the performance ?
One thing everybody must understand is that the "statistical parameters" for scientists, and for a coach, are completely different.
For researchers, the Group "elite" when they study the effects of running a Marathon includes athletes from the WR holder till 2:45. The Group of generally considered "well trained athletes" is between 2:45 and 4 hours.
The Group of "athletes with moderate training" includes runners between 4:00 and 5:00.
Instead, for a coach, athletes running in 2:11 are part of a totally different Group, as demonstrated by the all-time lists, because till now there are 1189 runners who ran under 2:11.
Personally, I already have problems to consider an athlete running 2:05:42 in the same class of the best, since at the moment this athlete is number 50 all time.
More data the researchers collect around average athletes, more deviation there is from the values of elite athletes.
The reality is that THERE ARE NOT RESEARCHES SPECIFICALLY CARRIED OUT with elite athletes.
In more than 30 years of my activity as coach of athletes of international level (not only African), too many times I saw situation well different from what the "classic" methodology had teached, and I found a lot of data very far from the data produced by the "official" physiology.
I agree that physiology should explain the effects of training, and of doping, on the athletes, but the reality is that almost the totality of scientific investigation are carried out on a sampling very far, and very different, from every elite athlete.
Of course, the human body is Always a human body, like a cas is Always a car. However, also if their mecanical principle are the same, I can't study a Fiat 500 for evaluating a Formula One.
There are too many assertions in the study of the Swedish scientists that are not correct, if referred to elite runners. For example, "the results show a close relationship between VO2 max and Hb" that really doesn't exist, since we have athletes with very high VO2 max but low Hb, and athletes with high Hb and low VO2 max. Not only, but VO2 max, in spite of the fact that physiologists continue to consider it an important parameter, has very little influence on the performance of endurance, of course inside a range very wide, but including high values. For example, the first athletes able running a Marathon under 2:10, the Aussie Derek Clayton, had a VO2 max of 69, very far from athletes who never were able to run so fast.
The fact is that I can't explain with the positions of the official physiology what I often see in training. And is not the training depending on physiology, but physiology depending on training, such as any experimental science.
So, I can describe what happens (this is a fact), and physiologists must explain the reason. The problem is that they are not able to explain what training of high level produces, because they don't know what this training is, and never have the opportunity to study a period of training of the best athletes, since training is a dynamic process, while their tests, following the classic protocolls, are "static pictures" of the final situation.