Effects of prolonged low doses of recombinant human erythropoietin during submaximal and maximal exercise

The aim of this study was to characterise the effect of prolonged low doses of recombinant erythropoietin (r-HuEPO) on the responses to submaximal and maximal exercise. Volunteer recreational athletes (n=21) were divided into three groups: r-HuEPO+intravenous iron (EPO+IV, n=7), r-HuEPO+oral iron (EPO+OR, n=9) and placebo (n=5). During the 12 week study, r-HuEPO or saline injections were given three times a week for the first 8 weeks and for the final 4 weeks the subjects were monitored but no injections were administered. The r-HuEPO doses were 50 IU·kg–1 body mass for 3 weeks and 20 IU·kg–1 body mass for the next 5 weeks. An exercise test comprising three submaximal intensities and then increments to elicit maximal aerobic power (\(\dot V{\rm O}_{{\rm 2max}} \) ) was conducted during weeks 0, 4, 8 and 12. During week 0, the mean intensity of the submaximal stages was 60%, 72% and 81% \(\dot V{\rm O}_{{\rm 2max}} \) . Blood taken at rest was analysed twice a week for haematocrit (Hct). The relative increases in \(\dot V{\rm O}_{{\rm 2max}} \) at weeks 4, 8 and 12 were 7.7%, 9.7% and 4.5%, respectively, for the EPO+IV group; 6.0%, 4.7% and 3.1% for the EPO+OR group; and –0.5%, –0.1% and –1.0% for the placebo group, where the improvements at week 12 for the EPO+IV and EPO+OR groups remained significantly above week 0 values. The Hct was significantly elevated by 0.06 and 0.07 units at week 3 in the EPO+IV and EPO+OR groups, respectively, and was stable during the 5 weeks of low-dose r-HuEPO. After 8 weeks of r-HuEPO use, plasma lactate concentration tended to be lower at exercise intensities ranging from 60% to 100% \(\dot V{\rm O}_{{\rm 2max}} \) . This study confirmed the ability of low doses of r-HuEPO to maintain Hct and \(\dot V{\rm O}_{{\rm 2max}} \) at elevated levels.