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Andersen N.E.,U.S. Army | Karl J.P.,U.S. Army | Cable S.J.,Experimentation and Analysis Element | Williams K.W.,Experimentation and Analysis Element | And 4 more authors.
Journal of the International Society of Sports Nutrition | Year: 2010

Vitamin D is an essential nutrient for maintaining bone health. Recent data suggest that vitamin D and calcium supplementation might affect stress fracture incidence in military personnel. Although stress fracture is a health risk for military personnel during training, no study has investigated changes in vitamin D status in Soldiers during United States (US) Army basic combat training (BCT). This longitudinal study aimed to determine the effects of BCT on 25-hydroxyvitamin D (25(OH)D) and parathyroid hormone (PTH) levels in female Soldiers. Serum 25(OH)D and PTH were assessed in 74 fasted Soldier volunteers before and after an 8-week BCT course conducted between August and October in Columbia, South Carolina. In the total study population, 25(OH)D levels decreased (mean ± SD) from 72.9 ± 30.0 to 63.3 ± 19.8 nmol/L (P < 0.05) and PTH levels increased from 36.2 ± 15.8 to 47.5 ± 21.2 pg/mL (P < 0.05) during BCT. Ethnicity affected changes in vitamin D status (ethnicity-by-time interaction, P < 0.05); 25(OH)D decreased (P < 0.05) in both Hispanic and non-Hispanic whites, but did not change in non-Hispanic blacks. Ethnicity did not affect BCT-induced changes in PTH. These data indicate that vitamin D status in female Soldiers may decline during military training in the late summer and early autumn months in the Southeastern US. Future studies should strive to determine the impact of military clothing and seasonality on vitamin D status, as well as the functional impact of declining vitamin D status on bone health.© 2010 Andersen et al; licensee BioMed Central Ltd.

Margolis L.M.,U.S. Army | Pasiakos S.M.,U.S. Army | Philip Karl J.,U.S. Army | Rood J.C.,Louisiana State University | And 4 more authors.
Nutrients | Year: 2012

Fat-free mass (FFM) adaptations to physical training may differ between sexes based on disparities in fitness level, dietary intake, and levels of plasma amino acids (AA). This investigation aimed to determine FFM and plasma AA responses to military training, examine whether adaptations differ between male and female recruits, and explore potential associations between FFM and AA responses to training. Body composition and plasma AA levels were assessed in US Army recruits (n = 209, 118 males, 91 females) before (baseline) and every three weeks during basic combat training (BCT), a 10-week military training course. Body weight decreased in men but remained stable in women during BCT (sex-by-time interaction, P < 0.05). Fifty-eight percent of recruits gained FFM during BCT, with more (P < 0.05) females (88%) gaining FFM than males (36%). Total plasma AA increased (P < 0.05) during BCT, with greater (P < 0.05) increases observed in females (17%) then in males (4%). Essential amino acids (EAA) and branched-chain amino acids (BCAA) were increased (P < 0.05) in females but did not change in males (sex-by-time interaction, P < 0.05). Independent of sex, changes in EAA (r = 0.34) and BCAA (r = 0.27) from baseline were associated with changes in FFM (P < 0.05); greater (P < 0.05) increases in AA concentrations were observed for those who gained FFM. Increases in FFM and plasma AA suggest that BCT elicits a more pronounced anabolic response in women compared to men, which may reflect sex-specific differences in the relative intensity of the combined training and physiological stimulus associated with BCT. © 2012 by the authors; licensee MDPI, Basel, Switzerland.

Karl J.P.,U.S. Army | Lieberman H.R.,U.S. Army | Cable S.J.,Experimentation and Analysis Element | Williams K.W.,Experimentation and Analysis Element | And 2 more authors.
American Journal of Clinical Nutrition | Year: 2010

Background: Iron status degrades in female soldiers during military training. Inflammation-mediated up-regulation of hepcidin, a key mediator of iron homeostasis, may be a contributing factor. Objective: We measured the efficacy of an iron-fortified food product for maintaining iron status in female soldiers during basic combat training (BCT) and examined relations between iron status, serum hepcidin concentrations, and inflammation. Design: A randomized, double-blind, placebo-controlled trial was conducted. Volunteers received an iron-fortified food product (total dose = 56 mg Fe/d) or a placebo twice daily during the 9-wk BCT course. Iron-status indicators, serum hepcidin concentrations, and markers of inflammation were measured pre- and post-BCT. Results: BCT affected iron status; serum ferritin concentrations decreased (P ≤ 0.05), and concentrations of soluble transferrin receptor (sTfR) and hemoglobin and the red cell distribution width increased (P ≤ 0.05). Consumption of the iron-fortified food product attenuated declines in iron status in iron-deficient anemic soldiers; a group-by-time interaction was observed for hemoglobin and sTfR concentrations (P ≤ 0.05). Serum hepcidin concentrations were not affected by BCT; however, hepcidin concentrations were lower in iron-deficient anemic soldiers than in those with normal iron status (P ≤ 0.05) and were positively associated with serum ferritin (P ≤ 0.05) and C-reactive protein (P ≤ 0.05) concentrations pre- and post-BCT. Conclusions: Twice-daily consumption of an iron-fortified food product improved iron status in iron-deficient anemic soldiers but not in iron-normal or iron-deficient nonanemic soldiers. Serum hepcidin concentrations were not affected by training but were associated with iron status and inflammation pre- and post-BCT. This trial was registered at as NCT01100905. © 2010 American Society for Nutrition.

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