Electrolyte changes in plasma and urine of athletes during acute and rigorous bed rest and ambulatory conditions |
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Authors: | Yan G Zorbas Vassilly J Kakurin Viktor B Afonin Nikolai A Kuznetsov |
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Institution: | (1) Kosmic Biology and Medicine Institute, Krasno Selo, Sofia, Bulgaria;(2) Hypokinetic Physiology Laboratory, Odos Agias Sophias 81, GR-16232 Athens, Greece |
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Abstract: | Rigorous bed rest (RBR) induces significant electrolyte changes, but little it is not known about the effect of acute bed
rest (ABR) (i.e., abrupt confinement to a RBR). The aim of this study was to measure urinary and plasma electrolyte changes
during ABR and RBR conditions.
The studies were done during 3 d of a pre-bed-rest (BR) period and during 7 d of an ABR and RBR period. Thirty male trained
athletes aged, 24.4 ± 6.6 yr were chosen as subjects. They were divided equally into three groups: unrestricted ambulatory
control subjects (UACS), acute-bed-rested subjects (ABRS), and rigorous-bed-rested subjects (RBRS). The UACS group experienced
no changes in professional training and daily activities. The ABRS were submitted abruptly to a RBR regimen and without having
any prior knowledge of the exact date and time when they would be subjected to an RBR regimen. The RBRS were subjected to
an RBR regime on a predetermined date and time known to them from the beginning of the study.
Sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), and phosphate (P) in plasma and urine, plasma renin activity (PRA)
and plasma aldosterone (PA), physical characteristics, peak oxygen uptake, and food and water intakes were measured. Urinary
Na, K, Ca, Mg, and P excretion and plasma Na, K, Mg, Ca, and P concentration, PRA, and PA concentration increased significantly
(p ≤ 0.01), whereas body weight, peak oxygen uptake, and food and water intakes decreased significantly in the ABRS and RBRS
groups when compared with the UACS group. However, urinary and plasma Na, K, Mg, P, and Ca, PRA, and PA values increased much
faster and were much greater in the ABRS group than in the RBRS group. Plasma and urinary Na, K, Ca, Mg, and P, PRA and PA
levels, food and water intakes, body weight, and peak oxygen uptake did not change significantly in the UACS group when compared
with its baseline control values.
It was shown that RBR and ABR conditions induce significant increases in urinary and plasma electrolytes; however, urinary
and plasma electrolyte changes appeared much faster and were much greater in the ABRS group than the RBRS group. It was concluded
that the more abruptly motor activity is ended, the faster and the greater the urinary and plasma electrolyte change. |
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Keywords: | Sodium potassium calcium magnesium phosphate renin aldosterone food water body weight peak oxygen uptake |
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