Human Limits

Over the weekend, I joined Medical Edge Radio to talk about what makes Olympics athletes so successful in their chosen sport.  We also discussed how we can enjoy a little Olympics-inspired athleticism in our own life.

You can listen to the full segment online.

The Tour de France ended today and the Olympics will start in little less than a week.  My first two posts have been about doping in cycling and I thought it might a good time to look at this issue more broadly and ask if doping control can work.  This is a complex issue with differing interpretations of the same data.

1) There are a very limited number of positive tests.  Some argue that this is evidence that drug testing is working.  Others argue the tests are beatable and the limited number of positive tests prove the point.  In 2008 Joris Delhanghe and I wrote an editorial in the Journal of Applied Physiology related to testing for EPO and took the position that the tests are beatable.

The doping control agencies also seem to acknowledge this because a number of individuals who have been banned passed numerous tests and people can be banned with “non-analytical” evidence.  If the tests are so great who needs non-analytical evidence?  The best example is Marion Jones, one of the stars of the Sydney Olympics who was later banned and spent time in prison.  The bottom line is that the tests are beatable and the limited number of positive tests doesn’t tell us much about how well doping control is working.

2) Another argument is that performances are continuing to get faster and when large databases from elite cycling are considered increases in the average speed since the early 1990s “question the role of extra-physiological parameters in this recent progression.”  However, there is more recent data showing that things are slowing down suggesting that doping control might be having an effect.

Analysis of power outputs during climbs in the 2012 Tour suggests this is true.  A newer analytical approach to testing is the so-called biological passport which tracks blood parameters that might be altered by doping over time and looks for suspicious changes.  While this approach can’t ensure that doping isn’t happening, it may be able to level the playing field and keep excessive values for a number of factors related to performance in check.

In summary, this is a very complex topic with enough information, controversy, and angles for several books!  However, at least for EPO and drugs designed to improve oxygen transport there is some evidence that the biological passport is keeping doping in check.  However, doping is a cat and mouse game and there are a host of innovators out there who are looking for next best undetectable compound to use for an illegal edge.

During the Olympics I will focus on specific events to highlight issues related to human performance and focus on the factors that have led to improved records over time.

Note: when possible I will link to full copies of scientific papers.  If this is not possible due to copyright and access issues the links will be to a summary of the article of interest.

As noted in the first link below, Frank Schleck “withdrew” from the Tour de France after a positive test for a banned diuretic.  Diuretics have been used as “masking” substances to help beat routine testing for performance enhancing drugs.  They work by increasing urine output and can help “flush” banned substances out of the body or make the concentrations in the urine more dilute and less detectable.  Diuretics themselves would not improve performance.

In chatting with my colleague Dr. Alejandro Lucia from Spain, a leading expert on the physiology of cycling, current rumors suggest that a new class of experimental drugs that increase production of EPO are the next big thing in the peloton.  I am attaching links to a Washington Post article on the Schleck incident, a scientific paper on the new class of drugs that boost EPO production, and a paper by Dr. Lucia on the physiology of the Tour.

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.

With the Olympics kicking off next week, I was on Minnesota Public Radio’s “The Daily Circuit” this morning for a discussion on the making of elite athletes.

You can listen to the 40-minute segment online.