Calcium supplementation effect on calcium balance in endurance-trained athletes during prolonged hypokinesia and ambulatory conditions

Calcium (Ca) supplements may be used to normalize Ca-balance changes but little is known about the effect of Ca supplements on Ca balance during hypokinesia (decreased kilometers per day). The aim of this study was to evaluate the effect of daily intakes of Ca supplements on Ca balance during hypoki...

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Bibliographic Details
Published in:Biological trace element research 2000-03, Vol.73 (3), p.231-250
Main Authors: Zorbas, Y.G, Petrov, K.L, Kakurin, V.J, Kuznetsov, N.A, Charapakhin, K.P, Alexeyev, I.D, Denogradov, S.D
Format: Article
Language:English
Subjects:
Adult
Ambulatory care
Athletes
Calcium
Calcium - metabolism
Calcium, Dietary - pharmacology
Diet
dietary mineral supplements
Dietary supplements
Electrolytes - blood
Electrolytes - metabolism
Electrolytes - urine
excretion
Humans
Hypokinesia - metabolism
Kinetics
Male
nutrition
Oxygen Consumption - physiology
physical activity
Physical Endurance - physiology
Physical Fitness - physiology
Radioimmunoassay
sedentary life style
Water-Electrolyte Balance - physiology
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Summary:Calcium (Ca) supplements may be used to normalize Ca-balance changes but little is known about the effect of Ca supplements on Ca balance during hypokinesia (decreased kilometers per day). The aim of this study was to evaluate the effect of daily intakes of Ca supplements on Ca balance during hypokinesia (HK). Studies were done during 30 d of a pre-HK period and during 364 d of a HK period. Forty male athletes aged 23-26 yr were chosen as subjects. They were divided equally into four groups: unsupplemented ambulatory control subjects (UACS), unsupplemented hypokinetic subjects (UHKS), supplemented hypokinetic subjects (SHKS), and supplemented ambulatory control subjects (SACS). The SHKS and UHKS groups were kept under an average running distance of 0.7 km/d. In the SHKS and SACS groups supplemented with 35.0 mg Ca lactate/kg body weight. Fecal Ca loss, urinary excretion of Ca and phosphate (P), serum concentrations of ionized calcium (CaI) total Ca, P, and Ca balance, intact parathyroid hormone (iPTH) and 1,25 dihydroxyvitamin D (1,25(OH)2D), anthropometric characteristics and peak oxygen uptake were measured. Fecal Ca excretion, urinary Ca and P excretion, serum CaI, total Ca, and P concentration, and negative Ca balanced increased significantly (p < or = 0.01) in the SHKS and UHKS groups when compared with the SACS and UACS groups. Serum, urinary, and fecal Ca changes were much greater and appeared much faster in the SHKS group than in the UHKS group. Serum iPTH and 1,25 (OH)2 D, body weight, and peak oxygen uptake decreased significantly (p < or = 0.01) in the SHKS and UHKS groups when compared with the SACS and UACS groups. In contrast, the corresponding parameters remained stable in the SACS and UACS groups when compared with the baseline control values. It was concluded that during prolonged HK, urinary and fecal Ca excretion and serum Ca concentration increased significantly despite the presence of a negative Ca balance; thus, Ca supplements cannot be used to normalize negative Ca balance during prolonged HK.
ISSN:0163-4984
1559-0720
0163-4984
DOI:10.1385/BTER:73:3:231