title: Diurnal variations of serum erythropoietin in trained and untrained subjects.
abstract: 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.min-1.kg-1 versus 48.3 (SEM 1.4) ml.min-1.kg-1, 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 min) 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-1 versus 11.5 (SEM 2.1) U.l-1, 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-1; T: 16.2 (SEM 2.5) U.l-1, P > 0.05]. The mean 24-h [s-EPO] were 14.5 (SEM 1.0) U.l-1 and 14.9 (SEM 0.9) U.l-1 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 uptaken. Significant diurnal variations in [s-EPO] occurred in these healthy subjects irrespective of their levels of physical activity.
authors.affiliation: Department of Rheumatology, Hvidovre Hospital, Denmark.
authors.forename: T
authors.initials: T
authors.lastname: Klausen
authors.forename: F
authors.initials: F
authors.lastname: Dela
authors.forename: E
authors.initials: E
authors.lastname: Hippe
authors.forename: H
authors.initials: H
authors.lastname: Galbo
mesh_terms: D000704:Analysis of Variance; D015992:Body Mass Index; D002940:Circadian Rhythm / Q000502:physiology*; D004921:Erythropoietin / Q000097:blood*; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology; D013997:Time Factors
chemical_list: D004921:Erythropoietin