Abstract
Recombinant human erythropoietin (rHuEpo) increases haemoglobin mass (Hbmass) and maximal oxygen uptake ( O2 max).PurposeThis study defined the time course of changes in Hbmass, O2 max as well as running time trial performance following 4 weeks of rHuEpo administration to determine whether the laboratory observations would translate into actual improvements in running performance in the field.Methods19 trained men received rHuEpo injections of 50 IU•kg−1 body mass every two days for 4 weeks. Hbmass was determined weekly using the optimized carbon monoxide rebreathing method until 4 weeks after administration. O2 max and 3,000 m time trial performance were measured pre, post administration and at the end of the study.ResultsRelative to baseline, running performance significantly improved by ∼6% after administration (10∶30±1∶07 min:sec vs. 11∶08±1∶15 min:sec, p<0.001) and remained significantly enhanced by ∼3% 4 weeks after administration (10∶46±1∶13 min:sec, p<0.001), while O2 max was also significantly increased post administration (60.7±5.8 mL•min−1•kg−1 vs. 56.0±6.2 mL•min−1•kg−1, p<0.001) and remained significantly increased 4 weeks after rHuEpo (58.0±5.6 mL•min−1•kg−1, p = 0.021). Hbmass was significantly increased at the end of administration compared to baseline (15.2±1.5 g•kg−1 vs. 12.7±1.2 g•kg−1, p<0.001). The rate of decrease in Hbmass toward baseline values post rHuEpo was similar to that of the increase during administration (−0.53 g•kg−1•wk−1, 95% confidence interval (CI) (−0.68, −0.38) vs. 0.54 g•kg−1•wk−1, CI (0.46, 0.63)) but Hbmass was still significantly elevated 4 weeks after administration compared to baseline (13.7±1.1 g•kg−1, p<0.001).ConclusionRunning performance was improved following 4 weeks of rHuEpo and remained elevated 4 weeks after administration compared to baseline. These field performance effects coincided with rHuEpo-induced elevated O2 max and Hbmass.
Highlights
Erythropoietin is a glycoprotein hormone produced primarily in the kidney that regulates red blood cell mass by stimulating the survival, proliferation and differentiation of erythrocytic progenitors [1]
These field performance effects coincided with recombinant human erythropoietin (rHuEpo)-induced elevated v O2 max and heamoglobin mass (Hbmass)
Neocytolysis, the selective hemolysis of young circulating red blood cells which contributes to the regulation of red cell mass, seems to appear during specific conditions that cause a rapid decrease in erythropoietin levels such as spaceflight, high altitude exposure or blood doping [5,6,7,8,9]
Summary
Erythropoietin is a glycoprotein hormone produced primarily in the kidney that regulates red blood cell mass by stimulating the survival, proliferation and differentiation of erythrocytic progenitors [1]. Administration of recombinant human erythropoietin (rHuEpo) increases haemoglobin concentration by the well known increase in red blood cell mass and by a decrease in plasma volume [2,3,4]. The decrease in plasma volume, which precedes the increase in red cell mass, appears to be a rapid responding mechanism regulated by the renin-angiotensin-aldosterone system to control haematocrit [2,3]. Neocytolysis, the selective hemolysis of young circulating red blood cells which contributes to the regulation of red cell mass, seems to appear during specific conditions that cause a rapid decrease in erythropoietin levels such as spaceflight, high altitude exposure or blood doping [5,6,7,8,9]. Heamoglobin mass (Hbmass) and related blood volumes were repeatedly determined using the optimized carbon monoxide (CO)
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