# hematocrit levels and cycling...



## Winston Mcfail (Mar 7, 2011)

so recently my hematocrit levels testede at 56, which is a bit higher than i am comfortable with. ive been doing some reading and (i know nothing about cycling) almost across the board cyclists and endurance athletes have lower htc levels, and apparently a lot of you guys even try to raise it for performance reasons.

my question is, did any of you who have regular bloodwork done notice a drop in htc when you started cycling seriously? if so, then how much and at what point did you notice it?

also i found this study i thought i would post as i found it very interesting, and considering the MHP thread, i wanted to show that i do not find scientific studies useless.

http://www.ncbi.nlm.nih.gov/pubmed/3243695

ive been eating 1 grapefruit everyday....we will see.


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## Kerry Irons (Feb 25, 2002)

*Drop in Hct*



Winston Mcfail said:


> so recently my hematocrit levels testede at 56, which is a bit higher than i am comfortable with. ive been doing some reading and (i know nothing about cycling) almost across the board cyclists and endurance athletes have lower htc levels, and apparently a lot of you guys even try to raise it for performance reasons.
> 
> my question is, did any of you who have regular bloodwork done notice a drop in htc when you started cycling seriously? if so, then how much and at what point did you notice it?
> 
> ...


When the season is in full swing, most people experience an increase in plasma volume and therefore a drop in Hct. Yours is obviously very high, but whether that number puts you at risk is probably something to discuss with somebody in sports medicine. 

Before they had EPO tests, you couldn't race professionally if your Hct was over 50 unless you had a medical waiver. Some Dutch cyclists died because they juiced so heavily on EPO that their blood went to sludge. I don't remember ever seeing what their Hct numbers were, but both Bjarne Riis and Marco Pantani were tested at 60% and survived. YMMV


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## krisdrum (Oct 29, 2007)

I'm not totally following. Isn't hematocrit the oxygen carrying capacity of your blood (red blood cells)? Granted, there is a point where it can get too high and your blood thickens and could cause adverse effects (70% or more). But if memory serves, anti-doping considers anything between 41-50 normal range. So you have a greater capacity to carry oxygen, what's wrong with that? Are you worried about your blood thickening?


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## sdeeer (Aug 12, 2008)

krisdrum said:


> I'm not totally following. Isn't hematocrit the oxygen carrying capacity of your blood (red blood cells)? Granted, there is a point where it can get too high and your blood thickens and could cause adverse effects (70% or more). But if memory serves, anti-doping considers anything between 41-50 normal range. So you have a greater capacity to carry oxygen, what's wrong with that? Are you worried about your blood thickening?


Hematocrit is the percent of packed cell volume (red cells mainly) compared with the plasma. The typical range for men is 40-52%, so 56% is high. Dehydration can artificaially raise hematocrit. So will donating plasma (but most places load you up with saline after).

The actuall ability to carry O2 is based on red blood cell count. So for maximal O2 carrying capacity, you would want high blood volume and high hematocrit (with-in reason). Plasma volume increases with training and can decrease with exercise (causing hematocrit to creep up).

But just increasing O2 carrying capacity does not necessarily increase performace per se. The whole O2 kinetics as part of the Fick equation as well as the ability of the muclse to use that O2 are the rest of the picture.


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## Winston Mcfail (Mar 7, 2011)

sdeeer said:


> Plasma volume increases with training and can decrease with exercise (causing hematocrit to creep up).


im confused by this part of your post...it seems contradicting. did you mean it can decrease without exercise? maybe im missing it.


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## eddya (Aug 7, 2009)

Winston Mcfail said:


> im confused by this part of your post...it seems contradicting. did you mean it can decrease without exercise? maybe im missing it.


I think that was meant to read that during exercise, or right after exercise, dehydration can cause plasma levels to be lower than when you started.


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## sdeeer (Aug 12, 2008)

eddya said:


> I think that was meant to read that during exercise, or right after exercise, dehydration can cause plasma levels to be lower than when you started.


What I meant is that hematocrit goes up during exercise bouts. So if it is 45 at baseline, it may creep up to 46 at 15m, 47 by 45m, and 47.5 by 60+. 

In horses, their hct increases due to 'extra' red cells in the spleen. but in humans, hct goes up due to water loss to sweat and into interstitial spaces.


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## Zipp0 (Aug 19, 2008)

So....what I got out of this thread is "avoid grapefruit."

Ask your doc if you are concerned. People who live at higher altitudes have naturally higher crit and are perfectly fine. Are you a Sherpa by chance?


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