Phosphate deposition capacity of athletes during hypokinesia, phosphate loading, and ambulation |
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Authors: | Yan G Zorbas Vassily J Kakurin Nikolai A Kuznetsov Vladimir L Yarullin Ivan D Andreyev Kirill P Charapakhin |
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Institution: | (1) Kosmic Biology and Medicine Institute, Krasno Sello, Sofia, Bulgaria;(2) Hypokinetic Physiology Laboratory, Athens, Greece |
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Abstract: | Hypokinesia (diminished movement) induces significant phosphate (P) excretion; however, little is known about the P deposition
ability of the body during hypokinesia (HK). Using P loads, the aim of this study was to establish the deposition ability
of the body to retain P during prolonged HK. Studies were done during a 30-d period of pre-HK and a 364-d period of HK. Forty
male trained athletes aged 24.7 ± 8.0 yr were chosen as subjects. They were equally divided into four groups: unloaded ambulatory
control subjects (UACS), unloaded hypokinetic subjects (UHKS), loaded ambulatory control subjects (LACS), and loaded hypokinetic
subjects (LHKS). All hypokinetic subjects were limited to an average walking distance of 0.7 km/d. Loading tests with 85.0
mg of calcium phosphate/kg body weight were performed on the LACS and LHKS.
Fecal P loss, urinary calcium (Ca) and P loss, serum P, Ca, and the ionized calcium (CaI) levels increased significantly (p≤0.05) in the LHKS and UHKS groups when compared with the LACS and UACS groups, respectively. Serum intact parathyroid hormone
(iPTH) and the 1,25-dihydroxyvitamin D3 1,25-(OH)2 D3] levels decreased significantly (p≤0.05) in the LHKS and UHKS groups when compared with the LACS and UACS groups, respectively. After the P load, significant
(p≤0.05) differences were observed between LHKS and UHKS groups regarding serum, urinary, and fecal P changes. Thus, the deposition
capacity of P decreased significantly (p≤0.05) more in the LHKS group than in the UHKS group. The deposition of P, fecal P, urinary P and Ca, serum CaI, P, Ca, 1,25-(OH)2 D3, and iPTH changed insignificantly (p>0.05) in control groups when compared with their baseline values.
It was shown that after the P load, significant differences were observed between the loaded and unloaded hypokinetic subjects
regarding serum, urinary, and fecal P values and P retention. The oral P load intensified P loss from the body. It was concluded
that the higher the P intake increased the greater P loss and the lower P deposition and thus the less likely it is for the
P load to benefit hypokinetic subjects. |
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Keywords: | Phosphate deposition phosphate metabolism calcium parathyroid hormone 1 25-dihydroxyvitamin D |
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