Cross-sectional and longitudinal associations between physical activity, sedentary behaviour and bone stiffness index across weight status in European children and adolescents.

BACKGROUND: The associations between physical activity (PA), sedentary behaviour (SB) and bone health may be differentially affected by weight status during growth. This study aims to assess the cross-sectional and longitudinal associations between PA, SB and bone stiffness index (SI) in European children and adolescents, taking the weight status into consideration. METHODS: Calcaneus SI was first measured by quantitative ultrasound among children aged 2-9 years old in 2007/08. It was measured again after 2 years in the IDEFICS study and after 6 years in the I. Family study. A sample of 2008 participants with time spent at sports clubs, watching TV and playing computer/games self-reported by questionnaire, and a subsample of 1037 participants with SB, light PA (LPA) and moderate-to-vigorous PA (MVPA) objectively measured using Actigraph accelerometers were included in the analyses. Weight status was defined as thin/normal and overweight/obese according to the extended International Obesity Task Force criteria. Linear mixed-effects models were used to estimate the cross-sectional and longitudinal associations between PA, SB and SI percentiles, stratified by weight status. RESULTS: The cross-sectional association between weekly duration of watching TV and SI percentiles was negative in thin/normal weight group (ß = - 0.35, p = 0.008). However, baseline weekly duration of watching TV (ß = - 0.63, p = 0.021) and change after 2 years (ß = - 0.63, p = 0.022) as well as the change in weekly duration of playing computer/games after 6 years (ß = - 0.75, p = 0.019) were inversely associated with corresponding changes in SI percentiles in overweight/obese group. Change in time spent at sports clubs was positively associated with change in SI percentiles after 2 years (ß = 1.28, p = 0.001), with comparable effect sizes across weight status. In the subsample with accelerometer data, we found a positive cross-sectional association between MVPA and SI percentiles in thin/normal weight group. Baseline MVPA predicted changes in SI percentiles after 2 and 6 years in all groups. CONCLUSIONS: Our results suggested the beneficial effect of PA on SI. However, the increasing durations of screen-based SB might be risk factors for SI development, especially in overweight/obese children and adolescents.

Sex differences in the longitudinal associations between body composition and bone stiffness index in European children and adolescents.

Fat mass (FM) and fat free mass (FFM) may influence bone health differentially. However, existing evidences on associations between FM, FFM and bone health are inconsistent and vary according to sex and maturity. The present study aims to evaluate longitudinal associations between FM, FFM and bone stiffness index (SI) among European children and adolescents with 6 years follow-up. A sample of 2468 children from the IDEFICS/I.Family was included, with repeated measurements of SI using calcaneal quantitative ultrasound, body composition using skinfold thickness, sedentary behaviors and physical activity using self-administrated questionnaires. Regression coefficients (ß) and 99%-confidence intervals (99% CI) were calculated by sex-specified generalized linear mixed effects models to analyze the longitudinal associations between FM and FFM z-scores (zFM and zFFM) and SI percentiles, and to explore the possible interactions between zFM, zFFM and maturity. Baseline zFFM was observed to predict the change in SI percentiles in both boys (ß = 4.57, 99% CI: 1.36, 7.78) and girls (ß = 3.42, 99% CI: 0.05, 6.79) after 2 years. Moreover, baseline zFFM (ß = 8.72, 99% CI: 3.18, 14.27 in boys and ß = 5.89, 99% CI: 0.34, 11.44 in girls) and the change in zFFM (ß = 6.58, 99% CI: 0.83, 12.34 in boys and ß = 4.81, 99% CI: -0.41, 10.02 in girls) were positively associated with the change in SI percentiles after 6 years. In contrast, a negative association was observed between the change in zFM and SI percentiles in boys after 6 years (ß = -3.70, 99% CI: -6.99, -0.42). Besides, an interaction was observed between the change in zFM and menarche on the change in SI percentiles in girls at 6 years follow-up (p = .009), suggesting a negative association before menarche while a positive association after menarche. Our findings support the existing evidences for a positive relationship between FFM and SI during growth. Furthermore, long-term FM gain was inversely associated with SI in boys, whereas opposing associations were observed across menarche in girls.

Association between variants of neuromedin U gene and taste thresholds and food preferences in European children: Results from the IDEFICS study.

AIM: The neuropeptide neuromedin U (NMU) known for its role in appetite, feeding and energy balance could be involved in the control of food choice and taste sensitivity. We examined the association between NMU polymorphisms/haplotypes and taste thresholds and food preferences in a population of European children. METHODS: A total of 578 subjects from the IDEFICS study (mean age 7.5 ±â€¯0.8 SD, boys 53.6%) with NMU genotype data and food preference (salty, fatty, sweet, flavour and umami food) and taste threshold (salt, fat, sweet, umami) tests available were analysed. Three single nucleotide polymorphisms (SNPs; rs6827359, T:C; rs12500837, T:C; rs9999653, C:T) of NMU gene were analyzed and five major haplotypes were inferred. The associations between genotypes and food preferences or taste thresholds were investigated (odds ratios -OR, adjusted for age, sex and country). A p < 0.05 after false discovery rate adjustment (pFDR) was considered statistically significant. RESULTS: The association between NMU genotypes and food preference showed two NMU SNPs associated with preference for food containing sodium glutamate (umami taste; rs6827359C, OR = 1.61, 95% confidence interval (CI):1.20-2.17; rs9999653T, OR = 1.59, 95%CI:1.18-2.13). In the haplotype analysis, the CTT haplotype showed an OR of 1.70 (95%CI:1.16-2.5) for the umami food preference, while CCT haplotype showed an OR of 1.63 (95%CI:1.11-2.40), compared to the most frequent haplotype (TTC). Carriers of CCT/CCT vs subjects with no CCT haplotype showed an OR of 4.78 (95%CI:1.86-12.30). Umami food preference was associated with low values of BMI z-score, arm circumferences, skinfolds and fat mass (pFDR<0.05). No association between NMU genetic variants and taste thresholds was found. CONCLUSIONS: This study shows for the first time in children an association between preference for umami food and a NMU haplotype, previously found associated with low BMI values.

Social vulnerability as a predictor of physical activity and screen time in European children.

OBJECTIVES: To examine associations between social vulnerabilities and meeting physical activity (PA) and screen time (ST) recommendations during a 2-year follow-up. METHODS: 13,891 children aged 2.0 to  < 9.9 from eight European countries were assessed at baseline and 8482 children at follow-up. Children's sports club membership, PA and ST were collected via parental questionnaires. Moderate-to-vigorous physical activity (MVPA) was objectively assessed with accelerometers. Performing at least 1 h of MVPA daily and spending less than 2 h of ST defined physically active and non-sedentary children, respectively. Vulnerable groups were defined at baseline as children whose parents had minimal social networks, from non-traditional families, with migrant origin or with unemployed parents. Logistic mixed-effects analyses were performed adjusting for classical socioeconomic indicators. RESULTS: Children whose parents had minimal social networks had a higher risk of non-compliance with PA recommendations (subjectively assessed) at baseline. Migrants and children with unemployed parents had longer ST. All vulnerable groups were less likely to be sports club members. CONCLUSIONS: Migrants and children with unemployed parents are at risk for excessive ST and all vulnerable groups have lower odds of being sports club members.

Prevalence of overweight and obesity among 11-year-old children in Cyprus, 1997-2003.

OBJECTIVES: To report 5-year changes in the prevalence of overweight and obesity in 11-year-old children in Cyprus. METHODS: This was a school-based study performed in Cyprus. A total of 14,090 11-year-old children (males: 51.2%), who had been examined in the 1997-8 and 2002-3 school years, were included in the study. The International Obesity Task Force (IOTF) cut-offs were used to define overweight and obese subjects, and logistic regression models were used to estimate 5-year trends. RESULTS: The overall prevalence of overweight children was slightly higher in the second period but this change was not statistically significant. There was only a significant increase in overweight boys in rural areas; odds ratio (OR) (95% confidence interval [CI]) for the 5-year period was 1.33 (1.10, 1.62; p = 0.004). The overall relative increase in obesity was 17.9% and the OR (95% CI) was 1.22 (1.07, 1.38; p = 0.003). Although the prevalence of obesity was higher in males in both periods, the relative increase was substantially higher in females, 29.6% vs. 11.4%. The relative increase was also higher in rural (35.9%) compared with urban areas (8.7%); ORs (95% CI) 1.46 (1.17, 1.81) vs. 1.10 (0.94, 1.29), respectively. CONCLUSIONS: This is the first report documenting increasing rates of obesity among school-aged children in Cyprus. Females and children living in rural areas experienced the most striking increases. The prevalence of overweight increased only in males living in rural areas.

Association of adipose tissue arachidonic acid content with BMI and overweight status in children from Cyprus and Crete.

The relationships between n-3 and n-6 fatty acids in subcutaneous fat, BMI and overweight status were investigated in eighty-eight children from Crete and Cyprus. Overweight status, BMI and serum lipid levels were similar in children at both locations, but Cretan children had higher levels of total MUFA than Cypriot children (62.2 (sd 2.8) v. 52.2 (sd 2.8) % area, respectively, P<0.001) and consequently Cypriot children had higher levels of total saturated, polyunsaturated, trans, n-3 and n-6 fatty acids. Cypriot children had also higher levels of individual n-3 and n-6 fatty acids, specifically linoleic, alpha-linolenic and dihomo-gamma-linolenic acids. The variance of BMI was better explained (38.2 %) by adipose tissue arachidonic acid content than any other n-3 and n-6 fatty acids. Mean levels of arachidonic acid, dihomo-gamma-linolenic acid and docosahexaenoic acid were higher in overweight and obese subjects. All obese subjects fell in the 4th quartile of arachidonic acid levels, whereas 88.9 % of overweight subjects fell in the 3rd and 4th quartile of arachidonic acid. These results indicate positive associations between adipose tissue arachidonic acid and BMI and overweight status. Further research could clarify whether this association is causal.