Biology Reference
In-Depth Information
anonymous hot-line for athletes to call to request information about drugs and
sport. Committee reports indicate that the number of calls regarding rHuEPO
increased during the 1990s.
The lay sport literature reports widespread doping with erythropoietic pro-
teins in endurance sports such as track,cycling,and cross-country skiing.
These reports are largely confined to elite athletes competing in major events.
From the frequency of these sensational reports, one gains the impression that
such doping is common, but prevalence cannot be estimated from such data.
To date, neither college sport administrators nor the media have reported dop-
ing with erythropoietic proteins in the college sport population.
Now that a urine test for erythropoietic proteins (discussed later) is begin-
ning to be deployed, some additional data will be forthcoming from sports
organizations. The IOC, World Anti-Doping Agency, and international sport
federations are likely to periodically make summary data available. The nature
of these reports will vary, but in some cases, they will include the names of ath-
letes and the specific events. Since late in 2000, the media have reported sev-
eral cases of doping with erythropoietic proteins [21]. The media reports occur
many months before the adjudication proceedings that could find that doping
did not occur. By late 2002, CAS had heard two cases of alleged doping with
rHuEPO. In one case, the Court upheld the laboratory result and determined
that the athlete had doped with rHuEPO [22]. In the second case, CAS con-
cluded that rHuEPO doping had not been proven due to a flaw in the analysis
[23]. Although no one knows to what extent athletes use erythropoietic pro-
teins, it is increasingly obvious from all sources of data that they are being
used. Although the use currently appears to be confined to the highest echelons
of endurance sport, if the history of doping with other agents (notably steroids)
is any indication, their use will spread.
Does expanding the red cell mass enhance performance?
The underlying theory of doping is that increased oxygen-carrying capacity
increases performance of muscle tissue by increasing oxygen supply. The abil-
ity to perform sustained aerobic exercise depends on both oxygen delivery to
muscles and ability of the tissues to use it. Which of the two limits exercise
capacity has been the subject of many investigations and debates [13, 24-26].
VO
2 max
, a widely accepted index of physical fitness [27], correlates with red
cell mass [28], thereby supporting the hypothesis that an expanded red cell
mass enhances performance by increasing the amount of oxygen delivered to
muscle. The increase in blood viscosity due to increased concentrations of
hemoglobin does not limit delivery, as long as the hemoglobin concentration
is <20 g/L [29]. Other possible theories advanced to explain the increase exer-
cise capacity are that the expanded blood volume leads to increased cardiac
output, improved buffering capacity for the lactic acid accumulated during
exercise, and enhanced heat dissipation.
