This study explored the proportion of European youth who are sufficiently active according to physical activity (PA) recommendations, based exclusively on objective assessment through accelerometers. A systematic electronic search of studies published up to March 2012 was conducted. PubMed was used to identify accelerometry-assessed PA studies that involved European youth. Within the 131 European studies, only 35 clearly reported the proportion of youth meeting the PA recommendations. Different thresholds lying between 1000 and 4000 counts/min (cpm) were used to define moderate-to-vigorous PA (MVPA). Overall, up to 100% of youth may be sufficiently active when using a threshold of approximately >1000-1500 cpm. With the most cited cut-off point (i.e. >2000 cpm), up to 87% of European youth might be considered physically active with reference to the current recommendations. Alternatively, with a cut-off point >3000 cpm, no more than 3-5% of them appeared to achieve these recommendations. The large discrepancy in outcomes released by accelerometer data is mainly due to the variety of cut-off points for MVPA among youth, hindering the definition of a clear goal towards PA promotion in Europe. Standardization of methods is urgently required.

This study aims to compare three body mass index (BMI)-based classification systems of childhood obesity: the French, the International Obesity Task Force (IOTF) and the World Health Organization (WHO) references. The study involved 1382 schoolchildren, recruited from the Lille Academic District in France in May 2009 aged 8.4±1.7 years (4.0-12.0 years). Their mean height and body mass were 131.5±10.9cm and 30.7±9.2kg, respectively, resulting in a BMI of 17.4±3.2kg/m(2). The weight status was defined according to the three systems considered in this study. The agreement between these references was tested using the Cohen's kappa coefficient. The prevalence of overweight was higher with the WHO references (20.0%) in comparison with the French references (13.8%; P<0.0001) and the IOTF (16.2%; P≤0.01). A similar result was found with obesity (WHO: 11.6% vs. IOTF: 6.7%; or French references: 6.7%; P<0.0001). Agreement between the three references ranged from "moderate" to "perfect" (0.43≤κ≤1.00; P<0.0001). Kappa coefficients were higher when the three references were used to classify children as obese (0.63≤κ≤1.00; P<0.0001) as compared to classification in the overweight (obesity excluded) category (0.43≤κ≤0.94; P<0.0001). When sex and age categories (4-6 years vs. 7-12 years) were considered to define the overweight status, the lowest kappa coefficient was found between the French and WHO references in boys aged 7-12 years (κ=0.28; P<0.0001), and the highest one in girls aged 7-12 years between the French references and IOTF (κ=0.97; P<0.0001). As for obesity, agreement between the three references ranged from 0.60 to 1.00 (P<0.0001), with the lowest values obtained in the comparison of the WHO references against French references or IOTF among boys aged 7-12 years (κ=0.60; P<0.0001). Overall, the WHO references yield an overestimation in overweight and/or obesity within this sample of schoolchildren as compared to the French references and the IOTF. The magnitude of agreement coefficients between the three references depends on of both sex and age categories. The French references seem to be in rather close agreement with the IOTF in defining overweight, especially in 7-12-year-old children.

This study is aimed at updating the relationships between physical activity (PA) and the metabolic syndrome (MetS) and/or insulin resistance (IR) in youth. Cross-sectional, prospective cohort and intervention studies, which examined the effect of PA on MetS, its components and IR in children and adolescents (150 references. Of these, 37 studies were included. Twenty-six studies (70%) were cross-sectional observation studies, and two studies (8%) were prospective cohort studies. The remaining eight studies (22%) were interventions, of which three (<10% of all included studies) were randomized controlled trials. Commonly, higher PA levels were consistently associated with an improved metabolic profile and a reduced risk for MetS and/or IR in these populations. The impact of PA on MetS and/or IR appeared to be either independent of other factors, or alternatively or simultaneously mediated by the physical fitness and adiposity of youth. However, more-robustly designed interventions (i.e., some mega-randomized controlled trials based on lifestyle interventions) and additional cohort studies are required to make definitive inference about the magnitude and role of PA as a single genuine preventive and treatment strategy for the metabolic and cardiovascular risk of youth in the current obesogenic context.

Aim To evaluate the association between maternal physical activity and infant’s birth weight or risk of inappropriate weight for gestational age (GA), and whether this association differs by infant’s sex, maternal body mass index (BMI) or pregnancy complications in a prospective cohort study. Methods 1913 pregnant women from the 3D Birth Cohort (Québec, Canada) completed the Pregnancy Physical Activity Questionnaire at each trimester. Energy expenditure (metabolic equivalent of task (MET)*hours/week) for total activity, sports and exercise and vigorous intensity activities was calculated. The associations with birth weight and risk of inappropriate weight for GA were evaluated by regression modelling. Interactions were tested with infant’s sex, maternal prepregnancy BMI, gestational diabetes, hypertensive disorders and prematurity. Results Each 1 MET/hours/week increase in sports and exercise in the first trimester was associated with a 2.5 g reduction in infant’s birth weight (95% CI −4.8 to −0.3) but was not associated with the risk of small weight for GA. In contrast, although not significant, a 17% reduction in the risk of large weight for GA was observed with increasing sports and exercise. Furthermore, in women with subsequent pre-eclampsia (but not normotensive or hypertensive women), each 1 MET/hours/week increment spent in any vigorous exercise in the first trimester reduced the infant’s birth weight by 19.8 g (95% CI −35.2 to −4.3). Conclusions Pregnant women with higher sports and exercise levels in the first trimester delivered infants with a lower birth weight. The risk of reducing infant’s birth weight with vigorous exercise in women who develop pre-eclampsia later in pregnancy requires evaluation.

Paediatric research analysing the relationship between the easy-to-use anthropometric measures for adiposity and cardiometabolic risk factors remains highly controversial in youth. Several studies suggest that only body mass index (BMI), a measure of relative weight, constitutes an accurate predictor, whereas others highlight the potential role of waist-to-hip ratio (WHR), waist circumference (Waist C), and waist-to-height ratio (WHtR). In this study, we examined the effectiveness of adding anthropometric measures of body fat distribution (Waist C Z Score, WHR Z Score and/or WHtR) to BMI Z Score to predict cardiometabolic risk factors in overweight and obese youth. We also examined the consistency of these associations with the “total fat mass + trunk/legs fat mass” and/or the “total fat mass + trunk fat mass” combinations, as assessed by dual energy X-ray absorptiometry (DXA), the gold standard measurement of body composition. Anthropometric and DXA measurements of total and regional adiposity, as well as a comprehensive assessment of cardiometabolic, inflammatory and adipokines profiles were performed in 203 overweight and obese 7–17 year-old youths from the Paediatrics Clinic, Centre Hospitalier de Luxembourg. Adding only one anthropometric surrogate of regional fat to BMI Z Score improved the prediction of insulin resistance (WHR Z Score, R2: 45.9 %. Waist C Z Score, R2: 45.5 %), HDL-cholesterol (WHR Z Score, R2: 9.6 %. Waist C Z Score, R2: 10.8 %. WHtR, R2: 6.5 %), triglycerides (WHR Z Score, R2: 11.7 %. Waist C Z Score, R2: 12.2 %), adiponectin (WHR Z Score, R2: 14.3 %. Waist C Z Score, R2: 17.7 %), CRP (WHR Z Score, R2: 18.2 %. WHtR, R2: 23.3 %), systolic (WHtR, R2: 22.4 %), diastolic blood pressure (WHtR, R2: 20 %) and fibrinogen (WHtR, R2: 21.8 %). Moreover, WHR Z Score, Waist C Z Score and/or WHtR showed an independent significant contribution according to these models. These results were in line with the DXA findings. Adding anthropometric measures of regional adiposity to BMI Z Score improves the prediction of cardiometabolic, inflammatory and adipokines profiles in youth.