Clerk wrote:
Not sure what plasma expansion- the regular phenomena of hematocrit dripping after periods of intense exercise- has to donwith anything. It is not unique to East Africans, or altitude, or fully aerobically developed athletes. It has nothing to do with the claim Renato makes that the effect of EPO cannot enhance performance on top of the gains made from being fully trained at altitude.
disgraceful_admin wrote:You're clueless. How do you get internet in your van down by the river? Must've fallen on your head once too many while adjusting the antenna.
In the recent word of your likely hero: Wrong.
Can you show me a peer-reviewed publication in which already-developed athletes show sustained plasma expansion after months of training? Most literature states that contributions from erythropoiesis and plasma are of similar order and hematocrit is maintained, after an initial period up to a few weeks' training during which plasma volume rises faster than rbc volume.
If you've maxed out total blood volume and take EPO, you're not going to increase blood volume. You'll increase hematocrit at the expense of plasma volume, which is likely to decrease mean erythrocyte pulmonary transit time which will likely decrease oxygenation.
^There's the secret for all you LetsRun geniuses.
Here's the Simple English version:
Running lots builds pipes for your blood in the form of capillaries. You can only fit so many capillaries in your muscles, and can only fit so much blood in your body. Properly trained Kenyan world class distance runners (prokwoks) born and training at altitude essentially reach their limiting maximum blood volume.
If you take a prokwok and give him/her EPO, that'll increase their number of red blood cells. But since they're at their max blood volume, the plasma - the liquid component of blood outside of cells - volume will have to decrease or stay the same - there's hardly any place for more blood, it'll just get urinated out through the kidneys. So now you have a lower amount of plasma volume compared to red blood cell volume than you did before - a higher "hematocrit". And it's been shown that a lower plasma volume for a given hematocrit decreases the amount of time that a red blood cell spends in the capillaries of the lungs grabbing onto fresh oxygen and disposing of CO2. So now your prokwok's red blood cells are effectively worse per cell at oxygenating blood and fixing acidosis.
On the other hand, the prokwok has more red blood cells. Does this make up for having slightly less-oxygenated hemoglobin in the blood cells? No, because it is the gradient in oxygen which drives its diffusion, and on the relevant timescale of a red blood cell's passage through active muscle, the magnitude of the gradient matters much more than the density of red blood cells in getting that oxygen out and into the muscles. Not only that but more red blood cells increases blood viscosity which required higher energy expenditure by the heart and lowers venous return of blood from the extremities.
Giving a prokwok EPO effectively makes their blood slower and less useful.
My mistake. You are not talking about regular plasma expansion. I read your post quickly because I remembered an uninformed poster in the past who really harped on the topic. I remember the posts by Renato, he brought up data from his Chinese athletes, with other information brought up in later posts. (http://www.letsrun.com/forum/flat_read.php?thread=6669078&page=3#ixzz4Lg5pfnzw)
But with regard to blood viscosity (from EPO without any other products) interfering with performance, I posted this in that old thread, addressing the same issue:
Clerk wrote:
Even if, as you say, their lactate threshold would go down because of the higher viscosity (and the increased difficulty to clear blood lactate), that is a minimal effect compared to the increased energy output being produced. With performance improvements (albeit in non elite athletes) in the 10% range, even the fraction of that which a maximally trained athlete would get from increased HGB outweigh the impeded clearance at steady states of of 2,4, or 8 mmols of lactate caused by increased viscosity. Even more, this review claims that EPO allows the cardiac output to maintain itself despite the increased viscosity. The increased viscosity doesn't matter. This study wrote:
However, recent studies suggest that cardiac power rises after erythropoietin allowing an unchanged cardiac output in spite of increased viscosity.
http://www.ncbi.nlm.nih.gov/pubmed/20617487
Clerk wrote:With a further explanation here:
http://web.as.uky.edu/Biology/faculty/cooper/Cardiovascular%20issues-blood%20flow-%20viscosity-plaque/blood%20doping.pdf
At a first glance a change of the heart function after Epo is surprising. One might suggest that at exhaustion the heart is working to its limit because it reaches similar maximal heart rates under different conditions. However, in his review Ekblom [22] mentions that Epo causes an increase in arterial blood pressure during exercise in contrast to blood infusion. Also in Lundby ’ s et al. [33] doping experiments in humans, blood pressure but not heart rate at V O 2 peak was increased after Epo: The heart delivered a markedly higher mechanical power ( + 18 %) estimated from the rate pressure product as well as calculated from stroke volume, systolic pressure and heart rate [10] at equal cardiac output as before Epo
Clerk wrote: That it is blood pressure, not the abilities of the heart that caused the effect, it is not an effect dependent on training status; elite athletes could still receive the increase in blood pressure that allows that pulminary output to accommodate the higher blood viscosity.
Full data for that claim is available on page 224
(That paper also does well to explain that there are benefits to EPO beyond carrying capacity. Although, like you point out, some are in contention.)
This paper
http://health120years.com/cn/pdf/hd_Nobel_1920_HD_Blood.pdfsays that
... there is about a 4% increase of blood viscosity per unit increase of hematocrit (e.g., a change from 45 to 46% hematocrit increases blood viscosity by 4%).19
Clerk wrote:. And given that well trained east african runners have a much lower hematocrit to start, the increase in viscosity is less at lower levels (see the chart linked.)
All in all, the body compensates for the increased viscosity. What you claim to be a negative effect that outweighs the benefits is not apparent. Moreover, we have seen athletes compete successfully at high levels of HCT (55%+), there is anecdotal evidence to show that the increased viscosity is not a large detriment, and that the benefits have outweigh any negatives.
