Artificial oxygen carriers - The new doping threat in endurance sport?

Maximal oxygen uptake is the major performance limiting factor in endurance sports. Sophisticated training methods have been developed to increase thi s variable. On the other hand, attempts have been made to improve maximal o xygen uptake by artificial means: blood doping and the misuse of recombinan t human erythropoietin have beneficial effects on aerobic exercise capacity . Both methods have been banned by international sporting federations. A ne w class of substances might represent the next step of fraudulent improveme nt of the maximal oxygen uptake: artificial oxygen carriers, such as soluti ons based on recombinant, bovine or human hemoglobin and perfluorocarbon-em ulsions have been shown to improve oxygen delivery to the muscle. Hemoglobi n-based solutions improve aerobic exercise capacity in animal and human tes ting. Both substances have potentially lethal side effects including renal toxicity, increased systemic and pulmonary blood pressure and impairment of the immune system. Hemoglobin-based carriers can be detected in drug testi ng with routine laboratory tests based on the detection of free hemoglobin. Perfluorocarbon is not metabolized by the body and exhaled through the lun g and can be measured with chromatography. No screening for these substance s in drug tests has been performed so far. International sporting federatio ns should be aware of this new, emerging doping threat.