BackgroundStrong evidence indicates that moderate-vigorous physical activity (MVPA) is positively associated with fitness in youth, independent of total sedentary-time. Sedentary-time appears negatively associated with fitness only when it replaces MVPA. However, whether different sedentary-patterns affect health-related fitness is unknown.MethodsThe associations between MVPA and sedentary-patterns with physical fitness were examined in 2698 youths (1262 boys) aged 13.4 ± 2.28 years. Sedentary-time (counts · minute−1 < 100) and PA were objectively measured by accelerometry. Each break (≥100 counts · min−1 < 2295) in sedentary-time and the frequency of daily bouts in non-prolonged (<30 min) and prolonged (≥30 min) sedentary-time were determined. The FITNESSGRAM® test battery was used to assess fitness. A standardized fitness composite-score (z-score) was calculated by summing the individual z-scores of the five tests adjusted to age and sex.ResultsPositive associations between MVPA and fitness were observed in both boys (β = 0.013, 95% CI: 0.005; 0.021) and girls (β = 0.014, 95% CI: 0.006; 0.022), independent of sedentary-patterns. Modest associations were found for the breaks in sedentary-time with fitness (β = 0.026, 95% CI: 0.009; 0.042), independent of total sedentary-time and MVPA in boys. In girls, non-prolonged sedentary bouts were positively associated with fitness (β = 0.014, 95% CI: 0.003; 0.024), independent of total sedentary-time and MVPA.ConclusionsThese results reinforce that, independent of the time and patterns of sedentary behavior, MVPA is consistently associated with fitness in youth. Modest and inconsistent associations were found for sedentary behaviors. Breaking-up sedentary-time in boys and non-prolonged sedentary bouts in girls were positively associated with fitness, independent of total sedentary-time and MVPA. In order to enhance youth’s fitness, public health recommendations should primarily target MVPA, still, suggestion to reduce and break-up sedentary-time may also be considered.

Interventions in the school environment seem to have a positive effect on CRF among adolescents, but there is high heterogeneity between studies. Some intervention characteristics can explain better effects on CRF (e.g. exercise sessions in addition to physical education classes; primary focus on this outcome; combination of aerobic and resistance exercises; classes lasting ≥60 min; frequency of three times weekly; and intensity control).

The aim of this study was to develop instructions for using accelerometers to measure physical activity in Brazil. This manuscript is a review and synthesis of scientific papers that have used accelerometers for objective physical activity assessment in different age groups as well as studies providing directions for using activity monitors in large-scale studies. In this study, we present instructions for the pre-data collection (selection of monitor; unit calibration, firmware update, pilot study, protocol definition), data collection (monitor distribution, contacting participants, monitor return) and post-data collection (data processing, transformation and interpretation) phases. We describe procedures for facilitating decision making related to using accelerometers, as well as for obtaining valid and reliable accelerometer physical activity data. This set of instructions is an initiative of a group of physical activity researchers with the purpose of contributing to methodologically advance the field of objective physical activity measurement in Brazil. The current set of instructions intend to facilitate the standardization of procedures for collecting physical activity data with accelerometers in Brazil and, thus, for ascertaining future comparability of data collected in different studies.

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The aim of this study was to identify the morphological configuration of youth athletes from professional soccer clubs and to verify their differences according to the tactical position on the field. Overall, 67 male players aged 15 to 17 years were evaluated. The examined anthropometric measurements included body mass, body height, skinfolds (triceps, subscapular, supraspinal and medial calf), girths (flexed and tensed arm and calf) and breadths (humerus and femur). For statistical purposes, analysis of variance and post hoc Bonferroni and Kruskal-Wallis tests were used. We concluded that goalkeepers were heavier and taller than center backs (p = 0.015 and p = 0.001), midfielders (p = 0.005 and p <0.001) and center forward players (p = 0.024 and p <0.001). The average somatotype for defense, forward and goalkeeper positions was a balanced mesomorph. Midfield players showed ectomorphic-mesomorph characteristics. It was concluded that goalkeepers were characterized as being taller and heavier and that somatotype features of athletes were similar between positions, except for midfield players.