Cycling performance enhancer rHuEPO ineffective, potentially harmful
Lance Armstrong was recently banned from cycling for life and stripped of his seven Tour de France titles following allegations of doping. In recent years, the sport of cycling has been tainted by doping with performance enhancing substances, including steroids, reinfusion of one’s own blood, and injections of recombinant human erythropoietin (rHuEPO). Although Armstrong may have used rHuEPO to increase his competitive edge, a new study has reported that the substance is unlikely to benefit elite athlete’s performing at Armstrong’s level. In addition, it poses a significant health risk. Dutch researchers published their findings online on December 6 in the British Journal of pharmacology.
Recombinant human erythropoietin is commonly used to treat anemia in patients with chronic renal failure; however, athletes of Armstrong’s caliber are not debilitated renal failure patients. The study authors note that rHuEPO is commonly used to enhance performance in cycling; thus, they conducted a qualitative systematic review of the available literature to obtain evidence whether the substance would significantly boost athletic prowess. They found no scientific basis to conclude rHuEPO has performance enhancing properties in elite cyclists. The noted that the studies that they reviewed had many shortcomings regarding translation of the results to professional cycling endurance performance. Furthermore, they cautioned that possible harmful side effects from taking rHuEPO were worrisome.
The researchers discussed VO2 max, or maximal oxygen uptake (VO2max, which is one factor that can determine an athlete’s capacity to perform sustained exercise; it is related to aerobic endurance. VO2 max refers to the maximum amount of oxygen that an individual can utilize during intense or maximal exercise. It is measured as “milliliters of oxygen used in one minute per kilogram of body weight.” The authors note that in elite endurance athletes, VO 2max can be 50% to 100% greater than those in normal healthy young people; however, that VO 2max plateaus in elite athletes while performance continues to improve. They suggest that this may be because of other factors involved in endurance such as high muscle capillary density, muscle metabolic adaptations such as increased mitochondria and oxidative enzymes, or more efficient biomechanics. Moderately trained athletes can improve a variety of factors to increase endurance performance; however, elite athletes primarily improve endurance performance by changes in lactate threshold, lactate turn point, and work economy or efficiency. None of these is directly altered by e rHuEPO.
In addition to be of unlikely benefit, rHuEPO increases the risk of serious side-effects such as a rise in systolic blood pressure, increased risk for thrombotic events (blood clots), increased blood viscosity (thickness), enhanced coagulation (blood cltting), endothelial activation and platelet reactivity, and inflammation. The authors warned that the aforementioned risk factors might increase the risk of thrombotic events (i.e., blood clots or strokes) in endurance performance athletes using rHuEPO. An increased red blood cell count might lower cerebral blood flow; thus, limiting oxygenation of the brain; thus, predisposing to cerebral infarction (ischemic stroke). They cited a case report that described a professional cyclist who was hospitalized for a cerebral sinus thrombosis. He admitted to three months of 2,000 IU rHuEPO use every two days, in combination with 15 days of growth hormone and continuous high doses of vitamin A and E.
The authors concluded that rHuEPO use in cycling is rife but scientifically unsupported by evidence and its use in sports is medical malpractice. They noted that a single well controlled trial in athletes under real life circumstances would provide a better indication of the real advantages and risk factors of rHuEPO use; however, it would be an oversimplification that this would eradicate its use.
Lance Armstrong won the Tour de France a record seven consecutive times between 1999 and 2005; however, in 2012 he was disqualified from all his results since August 1998 for using and distributing performance-enhancing drugs and was banned from professional cycling for life. Armstrong began his cycling career as a triathlete and became a national sprint-course triathlon champion in 1989 and 1990. In 1992, he began his career as a professional cyclist with the Motorola team. He had notable success between 1993 and 1996, including the 1993 World Championship, Clásica de San Sebastián in 1995, an overall victory in the penultimate Tour DuPont and a handful of stage victories in Europe, including the stage to Limoges in the Tour de France. In October 1996, he was diagnosed with testicular cancer that had spread to his brain and lungs. His cancer treatments included brain and testicular surgery and extensive chemotherapy. In February 1997, he was declared cancer-free and the same year he founded the Lance Armstrong Foundation for cancer support, which was later renamed the Livestrong Foundation. Due to pressure from the allegations, he stepped down as chairman of Livestrong last October and many of his personal sponsors dropped their contracts with him. To this day, Armstrong denies doping.
Reference: British Journal of pharmacology