Associations of fitness and physical activity with specific abdominal fat depots in children with overweight/obesity.

OBJECTIVES: To examine the relationship between physical fitness and physical activity (PA) with specific abdominal fat depots and their potential implications for cardiometabolic risk and insulin resistance (IR) in children with overweight/obesity. MATERIALS AND METHODS: A total of 116 children with overweight/obesity (10.7 ± 1.1 year, 54% girls) participated in the study. Abdominal visceral (VAT), subcutaneous (ASAT), and intermuscular abdominal adipose tissue (IMAAT) were assessed by magnetic resonance imaging. The cardiometabolic risk (MetS) score and the insulin resistance homeostasis model assessment (HOMA-IR) were calculated. Health-related physical fitness components (treadmill test, and 20 m shuttle run, handgrip, standing broad jump and 4 × 10 m tests) were evaluated, and PA was measured (accelerometry). Children were categorized as fit or unfit for each specific fitness test, and as active or inactive. RESULTS: Higher VAT, ASAT, and IMAAT were associated with higher MetS score and HOMA-IR (all p < 0.02). A better performance in all fitness tests and total and vigorous PA were strongly associated with lower VAT (all p < 0.04), ASAT (all p < 0.005), and IMAAT (all p < 0.005). Fit or active children had lower VAT, ASAT, and IMAAT (all p < 0.03) than their unfit or inactive counterparts. CONCLUSION: These results reinforce the importance of having adequate fitness and PA levels to reduce abdominal fat accumulation in children. Given that VAT, ASAT, and IMAAT are associated with higher risk of developing cardiovascular diseases and type 2 diabetes, the improvement of physical fitness by the promotion of PA should be goals of lifestyle interventions for improving health in children with overweight/obesity.

Impact of the choice of threshold on physical activity patterns in free living conditions among adolescents measured using a uniaxial accelerometer: the HELENA study.

The aim of this study was to assess the impact of the choice of threshold on physical activity patterns measured in adolescents under free living conditions (FLC) using a uniaxial accelerometer. The study comprised 2043 adolescents (12.5-17.5 years) participating in the HELENA Study. Participants wore a uniaxial accelerometer for 7 days. The PA patterns were assessed using thresholds determined from six different studies. For each of the thresholds used, the number of adolescents fulfilling the recommendation of 60 min of moderate to vigorous PA (MVPA) per day was also calculated. A significant difference was found between thresholds regardless of the activity level: differences of 38%, 207%, 136%, and 2780% for sedentary, light, moderate, and vigorous intensity PA, respectively (P < 0.001). Time of MVPA varied between methods from 25.3 to 55.2 min · day(-1). The number of adolescents fulfilling the recommendation varied from 5.9% to 37% according to the thresholds used. The kappa coefficient for concordance in the assessment of the number of adolescents achieving the PA recommendations was generally low. The definition of the threshold for PA intensity may considerably affect the PA patterns in FLC when assessed using a uniaxial accelerometer and the number of participants fulfilling the recommendations.

Interrater reliability and time measurement validity of speed-agility field tests in adolescents.

The aim of this study was to examine the interrater reliability (trained vs. untrained raters) and criterion-related validity (manual vs. automatic timing) of the 4 × 10-m shuttle run and 30-m running speed tests (times measured). The study comprised 85 adolescents (38 girls) aged 13.0-16.9 years from the Healthy Lifestyle in Europe by Nutrition in Adolescence study. The time required to complete the 4 × 10-m shuttle run and 30-m running tests was simultaneously measured (a) manually with a stopwatch by both trained and untrained raters (for interrater reliability analysis), and (b) by using photoelectric cells (for validity analysis). Systematic error, random error, and heteroscedasticity were studied with repeated-measured analysis of variance and Bland-Altman plots. The systematic error for untrained vs. trained raters and the untrained raters vs. photoelectric cells were in all cases ∼0.1 seconds (p < 0.01), that is, untrained raters recorded higher times. No systematic error was found between trained raters and photoelectric cells (p > 0.05). No heteroscedasticity was shown in any case (p > 0.05). The findings indicate that manual measurements by a trained rater, using a stopwatch, seem to be a valid method to assess speed and agility fitness testing in adolescents. Researchers must be trained to minimize the measurement error.

Self-reported physical activity in European adolescents: results from the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) study.

OBJECTIVE: To describe self-reported physical activity (PA) patterns in the various domains (school, home, transport, leisure time) and intensity categories (walking, moderate PA, vigorous PA) in European adolescents. Furthermore, self-reported PA patterns were evaluated in relation to gender, age category, weight status category and socio-economic status (SES). DESIGN: Cross-sectional study. SETTING: Ten European cities. SUBJECTS: In total, 3051 adolescents (47·6 % boys, mean age 14·8 (sd 1·2) years) completed an adolescent-adapted version of the validated International Physical Activity Questionnaire. RESULTS: The total sample reported most PA during leisure time (485 min/week) and least PA at home (140 min/week). Boys reported significantly more school-based PA (P < 0·001), leisure-time PA (P = 0·003), vigorous PA (P < 0·001) and total PA (P = 0·002) than girls, while girls reported more home-based PA (P < 0·001) and walking (P = 0·002) than boys. Self-reported PA at school (P < 0·001), moderate PA (P < 0·001), vigorous PA (P < 0·001) and total PA (P < 0·001) were significantly higher in younger age groups than in older groups. Groups based on weight status differed significantly only in leisure-time PA (P = 0·004) and total PA (P = 0·003), while groups based on SES differed in all PA domains and intensities except transport-related PA and total PA. CONCLUSIONS: The total sample of adolescents reported different scores for the different PA domains and intensity categories. Furthermore, patterns were different according the adolescents' gender, age, weight status and SES.