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A positive correlation was found between self-reported physical activity, leptin level, and Tanner stage 2 in children aged 10 to 12 years. However, several methodological considerations on the accuracy for assessing physical activity, misclassification of physical activity levels and weight status, the inclusion of possible confounds, and interpretation of the current findings should be examined to clarify the final interpretation.

Background & Aims: Failure to attain fat balance may contribute to obesity development even without excessive energy intake. The objective of this study was to examine the associations of dietary macronutrient distribution with abdominal adiposity in adolescents and to evaluate whether these relationships were attenuated by physical activity., Methods: A total of 224 Spanish adolescents (51% females, 14.9 ± 1.2 years) were included in the study. Abdominal adiposity in three regions, truncal and total body fat mass (FM) and lean mass (LM) were measured by dual-energy X-ray absorptiometry and thereafter FM index (FMI = FM/height(2)) and FMI/LMI ratio were calculated. The energy derived from fat intake was assessed by two non-consecutive 24 h recalls. Total physical activity (PA) and time spent in moderate-to-vigorous PA (MVPA) and vigorous PA were objectively measured by accelerometry., Results: We observed that the percent of energy derived from fat intake was significantly associated with FMI and FMI/LMI ratio (Ps = 0.001) and greater amounts of truncal (P = 0.001) and abdominal adiposity in the three regions regardless of age, sex and height (all P ≤ 0.005). The strength of the relationships was not substantially altered by further adjustment for PA, vigorous PA or moderate-to-vigorous PA (Ps ≤ 0.005)., Conclusions: The percent of energy derived from dietary fat intake is strongly and linearly associated with total, truncal and abdominal adiposity independently of PA in adolescents. These observations implicate the amount of dietary fat intake as a specific risk factor in the excess of abdominal adiposity in adolescence., (Copyright © 2013 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)

Background: Muscular fitness, cardiorespiratory fitness (CRF) and fatness are mutually related with chronic inflammation., Purpose: To examine the independent association of muscular fitness with inflammatory biomarkers in adolescents from nine European countries., Methods: A total of 639 adolescents (296 boys) aged from 12.5 to 17.5 year were included in this report. Data collection took place in 2006-2007 and analyses in 2012. A muscular fitness score was computed from handgrip strength and standing long jump. CRF was measured using the 20 m shuttle run test. Z-scores of C-reactive protein, complement factors C3 and C4, leptin and white blood cell counts were summed to create a cluster of inflammatory biomarkers. Sex, age, pubertal stage and centre were used as main confounders. Additional models were further adjusted for insulin resistance (HOMA-IR) and sum of four skinfolds., Results: Muscular fitness was negatively associated with single and clustered inflammatory biomarkers (standardized β from -0.399 to -0.100, all P-values < 0.05). Additional adjustments for CRF and HOMA-IR weakened the associations, but they still remained significant. The association was no longer significant when adjusting for skinfolds. Decreasing values of inflammatory score were observed across incremental levels of muscular fitness in both non-overweight and overweight adolescents (P ≤ 0.05)., Conclusions: Adolescents with higher levels of muscular fitness present a lower chronic inflammation, and this seems to be explained by lower levels of fatness. Yet, overweight and obese adolescents may exhibit a less adverse profile if they maintain appropriate levels of muscular fitness., (© 2013 The Authors. Pediatric Obesity © 2013 International Association for the Study of Obesity.)

To analyze the effects of an intervention focused on increasing the time and intensity of Physical Education (PE), on adolescents' cognitive performance and academic achievement. A 4-month group-randomized controlled trial was conducted in 67 adolescents from South-East Spain, 2007. Three classes were randomly allocated into control group (CG), experimental group 1 (EG1) and experimental group 2 (EG2). CG received usual PE (two sessions/week), EG1 received four PE sessions/week and EG2 received four PE sessions/week of high intensity. Cognitive performance (non-verbal and verbal ability, abstract reasoning, spatial ability, verbal reasoning and numerical ability) was assessed by the Spanish Overall and Factorial Intelligence Test, and academic achievement by school grades. All the cognitive performance variables, except verbal reasoning, increased more in EG2 than in CG (all P < 0.05). Average school grades (e.g., mathematics) increased more in EG2 than in CG. Overall, EG2 improved more than EG1, without differences between EG1 and CG. Increased PE can benefit cognitive performance and academic achievement. This study contributes to the current knowledge by suggesting that the intensity of PE sessions might play a role in the positive effect of physical activity on cognition and academic success. Future studies involving larger sample sizes should confirm or contrast these preliminary findings., (© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: The relevance of physical activity (PA) for combating cardiovascular disease (CVD) risk in children has been highlighted, but to date there has been no large-scale study analyzing that association in children aged ≤9 years of age. This study sought to evaluate the associations between objectively-measured PA and clustered CVD risk factors in a large sample of European children, and to provide evidence for gender-specific recommendations of PA., Methods: Cross-sectional data from a longitudinal study in 16,224 children aged 2 to 9 were collected. Of these, 3,120 (1,016 between 2 to 6 years, 2,104 between 6 to 9 years) had sufficient data for inclusion in the current analyses. Two different age-specific and gender-specific clustered CVD risk scores associated with PA were determined. First, a CVD risk factor (CRF) continuous score was computed using the following variables: systolic blood pressure (SBP), total triglycerides (TG), total cholesterol (TC)/high-density lipoprotein cholesterol (HDL-c) ratio, homeostasis model assessment of insulin resistance (HOMA-IR), and sum of two skinfolds (score CRFs). Secondly, another CVD risk score was obtained for older children containing the score CRFs + the cardiorespiratory fitness variable (termed score CRFs + fit). Data used in the current analysis were derived from the IDEFICS ('Identification and prevention of Dietary- and lifestyle-induced health EFfects In Children and infantS') study., Results: In boys <6 years, the odds ratios (OR) for CVD risk were elevated in the least active quintile of PA (OR: 2.58) compared with the most active quintile as well as the second quintile for vigorous PA (OR: 2.91). Compared with the most active quintile, older children in the first, second and third quintiles had OR for CVD risk score CRFs + fit ranging from OR 2.69 to 5.40 in boys, and from OR 2.85 to 7.05 in girls., Conclusions: PA is important to protect against clustering of CVD risk factors in young children, being more consistent in those older than 6 years. Healthcare professionals should recommend around 60 and 85 min/day of moderate-to-vigorous PA, including 20 min/day of vigorous PA.

Background: Physical activity (PA) is suggested to contribute to fat loss not only through increasing energy expenditure "per se" but also increasing muscle mass; therefore, it would be interesting to better understand the specific associations of PA with the different body's components such as fat mass and muscle mass. The aim of the present study was to examine the association between objectively measured PA and indices of fat mass and muscle components independently of each other giving, at the same time, gender-specific information in a wide cohort of European adolescents., Methods: A cross-sectional study in a school setting was conducted in 2200 (1016 males) adolescents (14.7 ± 1.2 years). Weight, height, skinfold thickness, bioimpedance and PA (accelerometry) were measured. Indices of fat mass (body mass index, % fat mass, sum of skinfolds) and muscular component (assessed as fat-free mass) were calculated. Multiple regression analyses were performed adjusting for several confounders including fat-free mass and fat mass when possible., Results: Vigorous PA was positively associated with height (p<0.05) in males, whilst, vigorous PA, moderate-vigorous PA and average PA were negatively associated with all the indices of fat mass (all p<0.01) in both genders, except for average PA in relation with body mass index in females. Regarding muscular components, vigorous PA showed positive associations with fat-free mass and muscle mass (all p<0.05) in both genders. Average PA was positively associated with fat-free mass (both p<0.05) in males and females., Conclusion: The present study suggests that PA, especially vigorous PA, is negatively associated with indices of fat mass and positively associated with markers of muscle mass, after adjusting for several confounders (including indices of fat mass and muscle mass when possible). Future studies should focus not only on the classical relationship between PA and fat mass, but also on PA and muscular components, analyzing the independent role of both with the different PA intensities.

Objective: To analyze the association between objectively assessed physical activity (PA) and markers of insulin resistance (IR) in European adolescents and to examine whether the association of objectively assessed PA and markers of IR is modified by cardiorespiratory fitness (CRF)., Methods: A cross-sectional study at school setting was conducted in 1053 (554 girls) adolescents (12.5-17.5 yr). Weight, height, waist circumference, total body fat, PA (accelerometry), and CRF (20-m shuttle run test) were measured. Fasting insulin and glucose concentrations were measured, and homeostasis model assessment as well as quantitative insulin sensitivity check index were computed., Results: In males, vigorous PA (VPA) was negatively associated with markers of IR after adjusting for confounders including waist circumference (all p < 0.05). In females, moderate PA, moderate to vigorous PA, and average PA were negatively associated with markers of IR after adjusting for confounders (all p < 0.05). Moreover, when the sample was segmented by CRF levels all the PA intensities were significantly associated with the markers of IR in females with low CRF but not in those with middle-high CRF after adjusting for confounders., Conclusions: The findings suggest that PA is negatively associated with markers of IR after adjusting for confounders including total and central body fat in both sexes, but this relationship is modified by the CRF levels being especially important in those females with low CRF. Preventive strategies should focus not only on increasing the volume of PA but also on enhancing CRF through VPA., (© 2013 John Wiley & Sons A/S.)

Hereby we summarize the work developed by the ALPHA (Assessing Levels of Physical Activity) Study and describe the tests included in the ALPHA health-related fitness test battery for children and adolescents. The evidence-based ALPHA-Fitness test battery include the following tests: 1) the 20 m shuttle run test to assess cardiorespiratory fitness; 2) the handgrip strength and 3) standing broad jump to assess musculoskeletal fitness, and 4) body mass index, 5) waist circumference; and 6) skinfold thickness (triceps and subscapular) to assess body composition. Furthermore, we include two versions: 1) the high priority ALPHA health-related fitness test battery, which comprises all the evidence-based fitness tests except the measurement of the skinfold thickness; and 2) the extended ALPHA health-related fitness tests battery for children and adolescents, which includes all the evidence-based fitness tests plus the 4 x 10 m shuttle run test to assess motor fitness.