Inadequacy of calcium supplements to normalize muscle calcium deficiency in healthy subjects during prolonged hypokinesia
2008
Zorbas, Yan G. | Kakuris, Kostas K. | Deogenov, Viktor A. | Yerullis, Kosmas B.
Objective: We investigated the effect of hypokinesia (diminished movement) on muscle calcium (Ca²⁺) content with and without Ca²⁺ supplementation and Ca²⁺ loss with different muscle Ca²⁺ deficiency; muscle Ca²⁺ content, plasma Ca²⁺ level, and Ca²⁺ loss were measured. Methods: Studies were performed in 40 physically healthy male volunteers during a pre-experimental period of 30 d and an experimental period of 364 d. Subjects in equal numbers were assigned to one of four groups: unsupplemented active control subjects (UACSs), unsupplemented hypokinetic subjects (UHKSs), supplemented active control subjects (SACSs), and supplemented hypokinetic subjects (SHKSs). A daily supplementation of 0.7 mmol of calcium lactate per kilogram of body weight was given to SACSs and SHKSs. Results: Muscle Ca²⁺ content decreased, and plasma Ca²⁺ concentration and Ca²⁺ loss in urine and feces increased (P < 0.05) in the SHKS and UHKS groups compared with their pre-experimental values and the values in their respective active control groups (SACS and UACS). However, muscle Ca²⁺ content decreased more, and plasma Ca²⁺ concentration and Ca²⁺ loss increased more (P < 0.05) in the SHKS group than in the UHKS group. Conclusion: Muscle Ca²⁺ deficiency is more evident when Ca²⁺ intake is higher and Ca²⁺ loss is more exacerbated with higher than with lower muscle Ca²⁺ deficiency, indicating that muscle Ca²⁺ deficiency during prolonged hypokinesia is due to an inability of the body to use Ca²⁺ but not to a Ca²⁺ shortage in the diet.
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