title: Association between bone stiffness and nutritional biomarkers combined with weight-bearing exercise, physical activity, and sedentary time in preadolescent children. A case-control study.
abstract: Physical activity (PA) and micronutrients such as calcium (Ca), vitamin D (25OHD), and phosphate (PO) are important determinants of skeletal development. This case-control study examined the association of these nutritional biomarkers and different PA behaviours, such as habitual PA, weight-bearing exercise (WBE) and sedentary time (SED) with bone stiffness (SI) in 1819 2-9-year-old children from the IDEFICS study (2007-2008). SI was measured on the calcaneus using quantitative ultrasound. Serum and urine Ca and PO and serum 25OHD were determined. Children's sports activities were reported by parents using a standardised questionnaire. A subsample of 1089 children had accelerometer-based PA data (counts per minute, cpm). Moderate-to-vigorous PA (MVPA) and SED were estimated. Children with poor SI (below the 15th age-/sex-/height-specific percentile) were defined as cases (N=603). Randomly selected controls (N=1216) were matched by age, sex, and country. Odds ratios (OR) for poor SI were calculated by conditional logistic regression for all biomarkers and PA behaviour variables separately and combined (expressed as tertiles and dichotomised variables, respectively). ORs were adjusted for fat-free mass, dairy product consumption, and daylight duration. We observed increased ORs for no sports (OR=1.39, p<0.05), PA levels below 524 cpm (OR=1.85, p<0.05) and MVPA below 4.2% a day (OR=1.69, p<0.05) compared to WBE, high PA levels (<688 cpm) and high MVPA (6.7%), respectively. SED was not associated with SI. ORs were moderately elevated for low serum Ca and 25OHD. However, biomarkers were not statistically significantly associated with SI and did not modify the association between PA behaviours and SI. Although nutritional biomarkers appear to play a minor role compared to the osteogenic effect of PA and WBE, it is noteworthy that the highest risk for poor SI was observed for no sports or low MVPA combined with lower serum Ca (<2.5 mmol/l) or lower 25OHD (<43.0 nmol/l).
authors.affiliation: Department of Epidemiological Methods and Etiologic Research, Leibniz Institute for Prevention Research and Epidemiology - BIPS, Achterstr. 30, 28359 Bremen, Germany. Electronic address: herrmann@bips.uni-bremen.de.
authors.forename: Diana
authors.initials: D
authors.lastname: Herrmann
authors.affiliation: Department of Biometry and Data Management, Leibniz Institute for Prevention Research and Epidemiology - BIPS, Achterstr. 30, 28359 Bremen, Germany. Electronic address: pohlabeln@bips.uni-bremen.de.
authors.forename: Hermann
authors.initials: H
authors.lastname: Pohlabeln
authors.affiliation: Research Centre in Epidemiology and Preventive Medicine - EPIMED, Department of Clinical and Experimental Medicine, University of Insubria, Via O Rossi 9, 21100 Varese, Italy; Department of Epidemiology and Prevention, IRCCS Istituto Neurologico Mediterraneo Neuromed, Via dell'Elettronica, 86077 Pozzilli, Italy. Electronic address: francesco.gianfagna@uninsubria.it.
authors.forename: Francesco
authors.initials: F
authors.lastname: Gianfagna
authors.affiliation: Department of Chronic Diseases, Centre of Behavioural and Health Sciences, National Institute for Health Development, Hiiu St 42, 11619 Tallinn, Estonia. Electronic address: kenn.konstabel@tai.ee.
authors.forename: Kenn
authors.initials: K
authors.lastname: Konstabel
authors.affiliation: Department of Public Health and Community Medicine, University of Gothenburg, Medicinaregatan 16, 40530 Gothenburg, Sweden. Electronic address: lauren.lissner@medfak.gu.se.
authors.forename: Lauren
authors.initials: L
authors.lastname: Lissner
authors.affiliation: Department of Paediatrics, Queen Silvia Children's Hospital, University of Gothenburg, Rondvägen 10, SE 41686 Gothenburg, Sweden. Electronic address: staffan.marild@pediat.gu.se.
authors.forename: Staffan
authors.initials: S
authors.lastname: Mårild
authors.affiliation: Department of Pediatrics, University of Pécs, József A. u. 7, 7623 Pécs, Hungary. Electronic address: molnar.denes@pte.hu.
authors.forename: Dénes
authors.initials: D
authors.lastname: Molnar
authors.affiliation: GENUD (Growth, Exercise, Nutrition and Development) Research Group, University School of Health Sciences, University of Zaragoza, C/Domingo Miral s/n, 50009 Zaragoza, Spain. Electronic address: lmoreno@unizar.es.
authors.forename: Luis A
authors.initials: LA
authors.lastname: Moreno
authors.affiliation: Institute of Food Sciences, National Research Council, Via Roma 64, 83100 Avellino, Italy. Electronic address: asiani@isa.cnr.it.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Siani
authors.affiliation: Department of Public Health, Ghent University, UZ 2 Blok A De Pintelaan 185, 9000 Ghent, Belgium. Electronic address: Isabelle.Sioen@UGent.be.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Sioen
authors.affiliation: Department of Chronic Diseases, Centre of Behavioural and Health Sciences, National Institute for Health Development, Hiiu St 42, 11619 Tallinn, Estonia. Electronic address: toomas.veidebaum@tai.ee.
authors.forename: Toomas
authors.initials: T
authors.lastname: Veidebaum
authors.affiliation: Department of Epidemiological Methods and Etiologic Research, Leibniz Institute for Prevention Research and Epidemiology - BIPS, Achterstr. 30, 28359 Bremen, Germany; Faculty of Mathematics and Computer Science, Bremen University, Bibliothekstr. 1, 28359 Bremen, Germany. Electronic address: ahrens@bips.uni-bremen.de.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Ahrens
mesh_terms: D061725:Accelerometry; D015415:Biomarkers / Q000378:metabolism*; D001842:Bone and Bones / Q000473:pathology*; D016022:Case-Control Studies; D002648:Child; D053198:Child Nutrition Sciences; D002675:Child, Preschool; D005060:Europe; D015444:Exercise; D005260:Female; D006801:Humans; D008019:Life Style; D008297:Male; D009043:Motor Activity; D009752:Nutritional Status; D016017:Odds Ratio; D012044:Regression Analysis; D057185:Sedentary Behavior; D013997:Time Factors; D016474:Weight-Bearing
chemical_list: D015415:Biomarkers
keywords: Bone health; Bone stiffness; Case–control study; Epidemiology; Quantitative ultrasound; Weight-bearing exercise