ABSTRACT
UNLABELLED: Recombinant human erythropoietin (rHuEpo) increases haemoglobin mass (Hb(mass)) and maximal oxygen uptake (v O(2 max)). PURPOSE: This study defined the time course of changes in Hb(mass), v O(2 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. METHODS: 19 trained men received rHuEpo injections of 50 IUâ¢kg(-1) body mass every two days for 4 weeks. Hb(mass) was determined weekly using the optimized carbon monoxide rebreathing method until 4 weeks after administration. v O(2 max) and 3,000 m time trial performance were measured pre, post administration and at the end of the study. RESULTS: Relative to baseline, running performance significantly improved by â¼6% after administration (10:30±1:07 min:sec vs. 11:08±1:15 min:sec, p<0.001) and remained significantly enhanced by â¼3% 4 weeks after administration (10:46±1:13 min:sec, p<0.001), while v O(2 max) was also significantly increased post administration (60.7±5.8 mLâ¢min(-1)â¢kg(-1) vs. 56.0±6.2 mLâ¢min(-1)â¢kg(-1), p<0.001) and remained significantly increased 4 weeks after rHuEpo (58.0±5.6 mLâ¢min(-1)â¢kg(-1), pâ=â0.021). Hb(mass) was significantly increased at the end of administration compared to baseline (15.2±1.5 gâ¢kg(-1) vs. 12.7±1.2 gâ¢kg(-1), p<0.001). The rate of decrease in Hb(mass) toward baseline values post rHuEpo was similar to that of the increase during administration (-0.53 gâ¢kg(-1)â¢wk(-1), 95% confidence interval (CI) (-0.68, -0.38) vs. 0.54 gâ¢kg(-1â¢)wk(-1), CI (0.46, 0.63)) but Hb(mass) was still significantly elevated 4 weeks after administration compared to baseline (13.7±1.1 gâ¢kg(-1), p<0.001). CONCLUSION: Running 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 v O(2 max) and Hb(mass).
