Friday, September 04, 2009

Demystifying the UCI's Biological Passport

For help in understanding the results captured by the UCI's Biological Passport system, or at least in trying to interpret them - may I suggest "A Tale of Two Cyclists" by Local Cyclist, here.

[NOTE: As I am not a hematologist, I take no responsibility for the accuracy of the information contained within the article that I link to or the excerpts presented here. But perhaps if you are of a science/medical background, you'll read the article and leave the appropriate feedback if necessary... You can also download a brochure by UCI on the Passport here.]

Some excerpts from "A Tale of Two Cyclists":

"Any minute now the cycling media is going to unleash a deluge of in depth articles analyzing the recently released bio passport data. Actually, that’s a lie. No instead, you the average cyclist will have to do your own analysis. I know, I know every time bio-passport data gets mentioned it comes with a disclaimer that only super doping experts are capable of looking at it without going blind. Fortunately, that’s not exactly true either.

So lets dive in and look at some Grand Tour data from two cyclists, MJ and BT.

MJ
Hgb 14.8 13.6 13.0
Hgb z 0.39 -1.42 -2.32
Retic 1.3 0.7 0.9

BT
Hgb 14.3 13.7 14.4 14 14.5
Hgb z -0.36 -1.19 -0.2 -0.7 -0.05
Retic 0.5 0.5 0.7 0.5 0.7

So what are we looking at. Hgb stands for Hemoglobin mass. Hemoglobin is the stuff in the red blood cells that carries oxygen. For simplicity, red blood cells = hemoglobin = oxygen = performance.

Rider MJ starts the tour with Hgb 14.8 and drifts down to 13.0. Rider BT starts at 14.3 starts to drift down pops up, drifts down, and pops up again to 14.5 just higher than where he started.

Hgb z stands for Hemoglobin z score. A z score is an indicator of where you are within your normal range, also called standard deviation. Typically, you are considered to be out of your normal range if you are higher than +2 (2 standard deviations above average) or less than -2 (2 standard deviations below your average).

Rider MJ starts the tour with a Hgb z of 0.39, just above average but well within the normal range. By the end of the tour he’s at -2.32, out of his normal range on the low side.
Rider BT starts the tour at -0.36 just below average but well within the normal range. Initially, he also trends down, to -1.19, below average but within the normal range. Then he recovers to -0.05 or basically back to average by the end of the Tour.

Retic stands for reticulocytes or immature (new) red blood cells. For simplicity Retic = how fast your body is making red blood cells.

Rider MJ starts out with a Retic of 1.3 at the upper end of normal. His Retic comes to the low side before recovering to 0.9. Overall MJ came in producing a lot of red blood cells and maintained decent production.

Rider BT starts out at 0.5 at the lower limit of normal trending up a little but still low. Overall, BT had a suppressed production of red blood cells.

To summarize, MJ comes in with an above average Hgb and a ramped up red blood cell production, maintains decent red blood cell production but his Hgb still drops low, well outside his normal range. BT on the other hand comes in with with a low Hgb and suppressed red blood cell production, never really ramps up red blood cell production yet finishes with a higher Hgb than when he started.

Before we try to make an interpretation, lets consider the relationship between Hgb and Retic, and the factors that effect blood values.

Hgb level is a balance between red blood cell destruction and production. It goes up when red blood cells are being produced faster than they are destroyed. It goes down when cells are destroyed faster than they are produced.

Accelerated destruction of red blood cells can be caused by, normal wear and tear, significant physical stress, and illness.

Slowing of destruction can be caused by; rest (less normal wear and tear).

Production of red blood cells (high Retic) can be caused by; low Hgb, altitude training, rest after physical stress, and EPO.

Suppression of red blood cell production (low Retic) can be caused by; high Hgb, physical stress, and illness.

Special considerations:

Dehydration: Hgb looks higher than it really is.

Volume expansion: Hgb looks lower than it really is.

Normal Patterns:
Grand Tour: Hgb decreases despite decent Retic count although retic should trend down as well.

Altitude: A modest rise in Retic is followed by modest rise in Hgb, that should not overcome significant physical stress. Returning to lower altitude should cause a tapering off of Retic and Hgb.

Recovery from physical stress: Initially Hgb and Retic are low followed by a moderate rise in Retic and Hgb. The effect should be suppressed by significant physical stress.

Chronic stress: Low Hgb, low Retic, and poor performance.

Dehydration: Hgb is higher than expected, variable Retic, and performance is decreased.

Enhanced patterns

Epo: Look for a large rise in Retic followed by rise in Hgb, persistently elevated Retic despite high Hgb, and the effect is strong enough to overcome significant physical stress.

Sudden stop of EPO: High Hgb combined with a very low Retic. Retic should fall dramatically and precede a significant fall in Hgb.

Blood transfusion: High Hgb very low retic, maintenance of Hgb despite significant physical stress and low Retic.

Blood withdrawal: Low Hgb despite high retic without some other explanation for red cell destruction.

Masking:

Transfusion plus volume expansion: Very low Retic despite what looks like a low to normal Hgb without other cause for suppression.

EPO plus volume expansion: High retic normal HgB, and an effect that can overcome significant physical stress.

Transfussion plus EPO micro dose: High Hgb, low normal Retic, and an effect that can overcome significant physical stress.

Transfusion plus volume expansion with EPO micro dose: Low to normal Hgb, low normal retic, and an effect that can overcome significant physical stress..." - A Tale of Two Cyclists

Full Article HERE. Again, hopefully those of you who are credentialed with provide LC with your feedback.

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