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Blood Value trends in a Stage Race: Understanding the Bio-Passport

October 17, 2013
basso_giro

Figure 1: Ivan Basso blood test results showing Hematocrit and Hemoglobin variations over a 21-day stage race from the Giro d’Italia 2010 (source: http://www.velonation.com/News/ID/4607/Bassos-biological-passport-numbers-from-Giro-dItalia-published.aspx).

Many simplify the notion of stress and blood changes to say that we should expect a downward trend in Hg/Hematocrit during a stage race – you’re body accumulates fatigue/stress and it supresses these values, makes sense right?  People hold up examples of this as indicative of a “clean” performance (see Figure 1 and the linked article discussing Ivan Basso’s 2010 GdI values).

A slight variation on the “downhill ride” shown in the Basso dataset, was that one in Figure 2, which shows Bradley Wiggins blood test values during his 2009 near-podium at the TdF.  Many commentators (not, to my knowledge, the Bio-Passport panel of experts) were skeptical of the “bump” in Wiggins values (see here for one such commentary in NYVelocity).  Some still argued that it was OK, since his overall trend was downward, while others made great issue of the 3rd value (labeled “Sion” in the graph) of 4.

Figure 2: Plot of OFF-score and Hemoglobin values for Bradley Wiggins from the 2009 Tour de France.

“V” is for Victory
Despite the allure of the simple notion, “if they have a downward trend, they are clean, if not, they’re doping”, it seems that the reality may be a bit more complex.  A recent study was released, which tracked values of over 250 cyclists through the “Baby Giro” a 10-day stage race.  This study found a trend that contradicted this simplistic “downhill” trend, stating that

Compared to baseline values, erythrocyte, hemoglobin, hematocrit, MCHC, platelet and reticulocyte counts were all consistently lower at mid-race, but returned to normal by race-end, while leukocytes were increased in the final phase

In other words, it was a “V” shaped curve (see figure 3).  What does this mean?  Well, this is of course open to speculation.  Some might say that since these are cyclists, who are therefore by definition dopers, that it is evidence of how it looks when you are doping.  Others might say, no, this is how the body responds to stress.  Still another point of view might be that this is only a 10-day stage race, so we cannot infer too much from this to a race of 21 stages.  Whatever the perspective, it’s complicated, and it if we accept that the majority of Baby Giro participants were clean, then it paints the “downhill = clean” notion as far too simplistic.  From my point of view, I don’t necessarily know what it means, but I would love to see this data from the TdF, Giro or Vuelta published year in and year out.  This would give yet another lens into comparison amongst individuals and trends within the peloton as a whole.

babygiro_HgHt

Figure 3: Plots of median value of Hematocrit (Ht) and Hemoglobin (Hg) for 253 riders from the 2010 and 2012 “Giro Bio”.

Disclaimer: I am not a physician, hematologist, anti-doping expert, or even a veterinarian.  I am just a coach and athlete who has a passion for data analysis, visualization and clean and fair sporting.

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