According to a study, EPO, a doping drug that was used by American cyclist Lance Amrstrong - for which his seven Tour de France titles was taken away from him- may have little effect on the performance of athletes.
One of the most celebrated athletes, the road racing cyclist Armstrong was the 1993 professional world champion, and had won the Tour de France a record seven consecutive times from 1999 to 2005.
However, in 2012, he was banned from sanctioned Olympic sports for life and stripped off his seven Tour de France titles after he confessed to using the drug erythropoietin (EPO).
Researchers from Centre for Human Drug Research in the Netherlands conducted a trial on about 48 well-trained non-professional male cyclists aged between 18 and 50 years.
They found that while performance was improved in high intensity tests, endurance and road race performances were similar for those who took the drug rHuEPO and those who did not.
They found that the drug led to elevated levels of haemoglobin and adhesion molecules which could potentially increase the risk of thrombosis.
In the trial, half of the participants were given weekly injections of rHuEPO, and half were given a placebo (saline solution) over 8 weeks.
The aim was to increase the levels of haemoglobin in the participants of the rHuEPO group by 10-15 per cent compared to the start of the study. The doses used were consistent with known practises in professional cycling.
The trial involved a series of tests to evaluate different types of performance parameters.
The first test involved a ramp test, where pedalling resistance was increased every 5 minutes until exhaustion (taking between 30-50 minutes).
The second test involved a 45 minute endurance test at the highest power output. The final test, 12 days after the final injections, involved a 110 kilometre (km) cycle followed by a 21.5 km road-race up Mont Ventoux, which often features in the Tour de France race.
Mean haemoglobin concentrations, and performance parameters in the high-intensity laboratory test were higher in the rHuEPO group compared to placebo. Gross efficiency, heart rate and other respiratory parameters did not differ between groups.
In the endurance tests, mean power output, oxygen consumption and Mont Ventoux race times did not differ between groups.
The same was true for cycling economy, mean heart rate, and lactate levels, researchers said.
There was no difference in adverse events between the two groups, however the endothelial function markers E-selectin and P-selectin were significantly increased in the rHuEPO group, potentially increasing the risk of thrombosis.
"We found that while rHuEPO increased performance in a laboratory setting on high intensity tests, the differences largely disappeared in endurance tests, and were undetectable in a real-world cycling race," said Jules Heuberger from the Centre for Human Drug Research.
The study was published in the journal The Lancet Haematology.