AUTHOR=Hoffmeister Torben , Schwenke Dirk , Krug Oliver , Wachsmuth Nadine , Geyer Hans , Thevis Mario , Byrnes William C. , Schmidt Walter F. J. 

TITLE=Effects of 3 Weeks of Oral Low-Dose Cobalt on Hemoglobin Mass and Aerobic Performance

JOURNAL=Frontiers in Physiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2018.01289

DOI=10.3389/fphys.2018.01289

ISSN=1664-042X

ABSTRACT=<p><bold>Introduction:</bold> Cobalt ions (Co<sup>2+</sup>) stabilize HIFα and increase endogenous erythropoietin (EPO) production creating the possibility that Co<sup>2+</sup> supplements (CoSupp) may be used as performance enhancing substances. The aim of this study was to determine the effects of a small oral dosage of CoSupp on hemoglobin mass (Hbmass) and performance with the objective of providing the basis for establishing upper threshold limits of urine [Co<sup>2+</sup>] to detect CoSupp misuse in sport.</p><p><bold>Methods:</bold> Twenty-four male subjects participated in a double-blind placebo-controlled study. Sixteen received an oral dose of 5 mg of ionized Co<sup>2+</sup> per day for 3 weeks, and eight served as controls. Blood and urine samples were taken before the study, during the study and up to 3 weeks after CoSupp. Hbmass was determined by the CO-rebreathing method at regular time intervals, and VO<sub>2max</sub> was determined before and after the CoSupp administration period.</p><p><bold>Results:</bold> In the Co<sup>2+</sup> group, Hbmass increased by 2.0 ± 2.1% (<italic>p</italic> &lt; 0.001) while all the other analyzed hematological parameters did not show significant interactions of time and treatment. Hemoglobin concentration ([Hb]) and hematocrit (Hct) tended to increase (<italic>p</italic> = 0.16, <italic>p</italic> = 0.1) and also [EPO] showed a similar trend (baseline: 9.5 ± 3.0, after 2 weeks: 12.4 ± 5.2 mU/ml). While mean VO<sub>2max</sub> did not change, there was a trend for a positive relationship between changes in Hbmass and changes in VO<sub>2max</sub> immediately after CoSupp (<italic>r</italic> = 0.40, <italic>p</italic> = 0.11). Urine [Co<sup>2+</sup>] increased from 0.4 ± 0.3 to 471.4 ± 384.1 ng/ml (<italic>p</italic> &lt; 0.01) and remained significantly elevated until 2 weeks after cessation.</p><p><bold>Conclusion:</bold> An oral Co<sup>2+</sup> dosage of 5 mg/day for 3 weeks effectively increases Hbmass with a tendency to increase hemoglobin concentration ([Hb]) and hematocrit (Hct). Because urine Co<sup>2+</sup> concentration remains increased for 2 weeks after cessation, upper limit threshold values for monitoring CoSupp can be established.</p>