Measurements in calcium-supplemented athletes during and after hypokineticand ambulatory conditions

Study objective: Hypokinesia (diminished movement) induces significant calc ium (Ca) changes, however, little is known about Ca deficiency during hypok inesia (HK). By using Ca supplements during and after HK, the aim of this s tudy was to establish whether HK could contribute to Ca deficiency. Design and methods: Studies were done during the pre-HK period of 30 days, HK period of 364 days and post-HK period of 30 days. Forty male trained ath letes aged, 25.0 +/- 7.7 yr were chosen as subjects. They were equally divi ded into four groups: unsupplemented ambulatory control subjects (UACS), un supplemented hypokinetic subjects (UHKS), supplemented ambulatory control s ubjects (SACS), and supplemented hypokinetic subjects (SHKS). The SHKS and SAGS groups took daily 55.0 mg elemental Ga per kg body weight. Hypokinetic subjects were limited to an average walking distance of 0.7 km/day, while the control subjects were running 11.6 km/day. Results: Fecal Ca, urinary Ca, and urinary phosphate (P) excretion, serum i onized calcium (Ca-1), P and total Ca levels, intact parathyroid hormone (i PIH), 1,25 dihydroxyvitamin D (1,25 (OH)(2) D-3), fluid and food intakes, p eak oxygen uptake, and physical characteristics were measured. During HK fe cal Ca, urinary Ca, and urinary P excretion and serum P, Ca-1, and Ca level increased significantly (p less than or equal to 0.01), whereas during the initial days of post-HK decreased significantly (p less than or equal to 0 .01) in the SHKS and unsupplemented hypokinetic subjects groups when compar ed with the SAGS and UACS groups, respectively. During HK serum 1,25 (OH)(2 ) D-3, iPTH levels, food and fluid intakes, body weight, body fat, and peak oxygen uptake decreased significantly (p less than or equal to 0.01), whil e during the initial days of post-HK remained significantly (p less than or equal to 0.01) depressed and fluid intakes increased significantly (p less than or equal to 0.01) in the SHKS and unsupplemented hypokinetic subjects groups when compared with SAGS and UACS groups, respectively. Serum, urina ry and fecal Ca changed much more in the SHKS than UHKS. Serum, fecal, and urinary minerals, iPTH, 1,25 (OH)(2) D-3 levels, food and fluid intakes, bo dy weight, body fat, and peak oxygen uptake did not change markedly in the SAGS and UACS groups when compared with their baseline values. Conclusion: It was shown that serum Ca concentration, urinary, and fecal Ca excretion increased during HK and decreased significantly during post-HK. Oral Ca supplementation did not significantly affect serum Ca levels or uri nary and fecal Ca loss. It was concluded that decreased urinary and fecal C a loss during post-HK, may suggest the presence of Ga deficiency during pro longed HK. Copyright (C) 2000 The Canadian Society of Clinical Chemists.