Human Limits

Recent news reports about the ongoing Lance Armstrong doping investigation raise some interesting issues.

The arguments that Mr. Armstrong was a serial doper go something like this:

• Doping was endemic in cycling, and there is no way he could have been so dominant for so long when the competition was clearly doping.
• Testimony from former teammates about systematic doping on the Armstrong-centered teams.

The arguments that Mr. Armstrong is clean go something like this:

• He passed an extraordinary number of doping control blood tests.
• At least for now, no trails of incriminating cell phone, FedEx, and/or financial records have emerged suggesting a series of suspicious transactions with suspicious people.

We know from the Marion Jones case that it is possible to beat the testing system, and that in many cases those who advise elite athletes about doping are one step ahead of the enforcement technology. We also know that many high-profile doping bans have centered on non-analytical findings, such as paper or electronic trails of suspicious transactions.

Now there is a report in the NY Daily News that offers a glimpse into data from blood tests that might be incriminating for Mr. Armstrong. The article reports that over a period of a couple of weeks in 2009, Mr. Armstrong’s hematocrit, an index of the ratio of red cells to plasma in the blood, increased by about 19% — from 38.2 to 45.7.

While that is certainly interesting and could be associated with EPO use or blood doping, it is well-known that hematocrit can vary widely on the same day in the same person.

Hematocrit variability

A 2005 study, Postural Pseudoanemia: Posture-Dependent Change in Hematocrit, shows that with just 30 minutes of standing, hematocrit can increase by an average of 11%, but by as much as 25%, as water essentially leaves the blood vessels and the red cells remain. There is also a 3-5% test-retest variability on the same sample from the same person.

Also, in addition to posture, hematocrit can be influenced by:

• Time of day
• Hydration status
• Recent exercise
• Use of a tourniquet during collection
• Variability when samples are run on different machines in different labs
• Altitude exposure

The bottom line: If this is the most incriminating biological data that the USADA has on Mr. Armstrong, it will be a piñata for a smart lawyer.

This entry was posted on Thursday, July 19th, 2012 at 3:53 pm and is filed under Current Events, Elite Sports Performance, Physiology. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.