, Volume 86, Issue 5, pp 442-449

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

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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.