Hemoglobin Mass, Blood Volume and VOmax of Trained and Untrained Children and Adolescents Living at Different Altitudes.

To a considerable extent, the magnitude of blood volume (BV) and hemoglobin mass (Hbmass) contribute to the maximum O-uptake (VOmax), especially in endurance-trained athletes. However, the development of Hbmass and BV and their relationships with VOmax during childhood are unknown. The aim of the present cross-sectional study was to investigate Hbmass and BV and their relationships with VOmax in children and adolescents.

Quantification of testosterone-dependent erythropoiesis during male puberty.

New Findings: What is the central question of this study? To what extent does testosterone influence haemoglobin formation during male puberty? What is the main finding and its importance? In boys, testosterone might be responsible for about 65% of the increase in haemoglobin mass during puberty. The underlying mechanisms are assumed to be twofold: (i) indirectly, mediated by the increase in lean body mass, and (ii) directly by immediate testosterone effects on erythropoiesis. Thereby, an increase in testosterone of 1 ng/ml is associated with an increase in haemoglobin mass of ∼65 g.