The evolving science of detection of 'blood doping'

Abstract

Blood doping practices in sports have been around for at least half a century and will likely remain for several years to come. The main reason for the various forms of blood doping to be common is that they are easy to perform, and the effects on exercise performance are gigantic. Yet another reason for blood doping to be a popular illicit practice is that detection is difficult. For autologous blood transfusions, for example, no direct test exists, and the direct testing of misuse with recombinant human erythropoietin (rhEpo) has proven very difficult despite a test exists. Future blood doping practice will likely include the stabilization of the transcription factor hypoxia-inducible factor which leads to an increased endogenous erythropoietin synthesis. It seems unrealistic to develop specific test against such drugs (and the copies hereof originating from illegal laboratories). In an attempt to detect and limit blood doping, the World Anti-Doping Agency (WADA) has launched the Athlete Biological Passport where indirect markers for all types of blood doping are evaluated on an individual level. The approach seemed promising, but a recent publication demonstrates the system to be incapable of detecting even a single subject as 'suspicious' while treated with rhEpo for 10-12 weeks. Sad to say, the hope that the 2012 London Olympics should be cleaner in regard to blood doping seems faint. We propose that WADA strengthens the quality and capacities of the National Anti-Doping Agencies and that they work more efficiently with the international sports federations in an attempt to limit blood doping.

Figure 1

Influence of changes in (A) [Hb] and (B) nHb at the individual level on VO_2max. All data have been collected by the authors during experimental work conducted at the Copenhagen Muscle Research Centre between 2002 and 2006.

Figure 2

(A) Correlation between [Hb] (mmol·L⁻¹) and haematocrit (%) values in world class cross-country skiers; (B) Effect of various daily activities in world class cross-country skiers (n = 12) on [Hb; mmol·L⁻¹] on two separate days (black and white bars). ‘20 min sitting +½ L’ indicates that the athlete drank ½ L of water while sitting for 20 min; ‘after training’ indicates that the sample was obtained after normal endurance training of 2–3 h of duration without fluid intake; ‘1 h + 2 L’ indicates that the sample was taken 1 h after completion of the training bout and that 1 L of water was drunk during this period); (C–F) correlation between haemoglobin mass (g·kg⁻¹ body weight) and haematocrit (%) with VO_2max (mL·min⁻¹·kg⁻¹ body weight) and 26 km time trial performance (W⁻¹·kg⁻¹ body weight) in elite cyclists (adapted from (Jacobs et al., 2011); and (G) Time span for %-changes in haematocrit (Htc), haemoglobin mass (nHb) and maximal aerobic power (VO_2max) (adapted from (Lundby et al., 2008a).

Figure 3

Based on testimonies from caught cyclists, confiscated diaries, etc., it is easy to unravel the blood doping strategy in present-day cycle sports. Here is the example of a cyclist aiming to perform well in Paris-Nice (seven stage race in March), a spring classic (one day race) in late April, and then in the Tour de France (three week stage race) in July, and also the world championships held in the autumn. Epo could then be abused in December, January and February in order to increase red cell mass. Once a sufficient red cell mass has been synthesized, one to three bags of blood are withdrawn and stored for later use. One to 2 days before Paris – Nice two blood bags will be infused and there will be likely no trace of Epo in blood or urine at this time point (Lundby et al., 2008a). Once the race is completed, the two blood bags will be withdrawn, stored and re-infused 1 to 2 days before the spring classic and again withdrawn and stored upon completion of the race (likely on the very same day). Epo injections are likely to occur in May where no major competitions are planned. Following 2–3 weeks of treatment, the gained blood is withdrawn and stored for later use. For the Tour de France in July, two blood bags are infused 1 to 2 days before the start, and then one blood bag is re-transfused on the two resting days. Since there is no direct doping test against autologous blood doping, this makes the doper very difficult to detect during competition, whereas a chance of getting caught exists during the Epo injection period by direct test, whereas the chance of getting caught by the blood passport seems minimal – again highlighting the importance of frequent out-of-competition testing. In this regard, it is surprising that a cyclist finishing within the very top in the 2010 world championships, and hence also a top contender for the 2011 championships, has not been tested since October 2010 (as of July 1st 2011, personal communication). Black circles indicate rhEPO injections, open red circles each indicate the withdrawal and storage of a one unit blood bag (i.e. two dots = two bags), and closed red circles each indicate the re-transfusion of one unit of blood. Red vertical lines indicate competitions. It should be kept in mind that this review only deals with blood doping and that substances such as growth hormone, IGF-1, anabolic steroids and doping ‘maskers’ are very likely also misused by this type of athlete.