Abstract des Autors

The diurnal variations of serum-erythropoietin concentration (<s-EPO>) were investigated in six physically trained (T) and eight untrained (UT) men. The T subjects had a higher mean maximal oxygen uptake than UT subjects (75.7 (SEM 1.6) ml/mm/kg versus 48.3 (SEM 1.4) ml/min/kg, P<0.0001) and a lower mean body mass index (BMI, 21.7 (SEM 0.7) kg/m**2 versus 24.4 (SEM 0.6) kg/m**2, P=0.02). Each subject was followed individually for 24 h as they performed their normal daily activities. Venous blood samples were collected from awakening (0 in) until the end of the 24-h period (1440 min). Both T and UT had a nadir of <s-EPO> 120 min after awakening (10.0 (SEM 0.3) U/l versus 11.5 (SEM 2.1) U/l, P>0.05). The UT and T increased their <s-EPO> to peak values at 960 min and 960-1200 min, respectively (ANOVA P=0.03) after awakening (UT: 18.4 (SEM 2.8) U/l; T: 16.2 (SEM 2.5) U/l, P>0.05). The mean 24-h <s-EPO> were 14.5 (SEM 1.0) U/l and 14.9 (SEM 0.9) U/l in T and UT, respectively (P>0.05). The individual mean 24-h <s-EPO> were not correlated to body mass, BMI or maximal oxygen uptake. Significant diurnal variations in <s-EPO> occurred in these healthy subjects irrespective of their levels of physical activity.