BackgroundThe aim of the study was to verify the association between body composition and physical fitness with bone status in children and adolescents.MethodsA cross-sectional study was conducted with 300 healthy students (148 boys, 152 girls). Weight, height, fat and fat-free mass, and percentage of body fat (%BF) were evaluated, as were physical fitness (abdominal exercise, flexibility, and horizontal jump tests) and maximum oxygen consumption. Bone parameters (amplitude-dependent speed of sound; AD-SoS) and the Ultrasound Bone Profile Index (UBPI) were evaluated using DBM Sonic BP ultrasonography.ResultsIn the study group, girls had higher bone parameter values than boys. A univariate analysis assessed in a stepwise multiple regression model was conducted. It showed that for boys, the %BF and height were significant independent variables for AD-SoS and UBPI, but the horizontal jump test only for AD-SoS (adjusted r2 = 0.274; p < 0.001), and pubertal maturation only for UBPI (adjusted r2 = 0.295; p < 0.001). For girls, age and %BF were identified as significant independent variables for AD-SoS and UBPI (adjusted r2 = 0.093; p < 0.001) but height only for AD-SoS (adjusted r2 = 0.408; p < 0.001).ConclusionsVariables related to growth (age, height, and pubertal maturation) are independent positive predictors for the bone parameters in both boys and girls. %BF is an independent negative predictor. For boys, the horizontal jump test was an independent positive predictor for AD-SoS, indicating that physical fitness related to the neuromotor system can influence the amount of bone present.

The phase angle is used to evaluate nutritional status and is an indicator of cellular health. Cardiorespiratory fitness and body composition are strong indicators of health during adolescence. We aimed to evaluate if body composition and cardiorespiratory fitness have an association with phase angle among adolescents. 203 girls and 220 boys (12.8±1.3 years) were evaluated. Peak height velocity, percentage fat mass, fat-free mass, cardiorespiratory fitness, and phase angle measurements were collected. Linear regression adjusted by peak height velocity was used to verify if predictor variables were associated with phase angle among adolescents. Phase angle showed correlation with fat-free mass (girls: r=0.42 and boys: r=0.37); with percent fat mass (girls: r=0.23); and with cardiorespiratory fitness (boys: r=0.19). Linear regression showed that percentage fat mass (in girls) and cardiorespiratory fitness (in boys) had an effect of 11 and 17% in phase angle, respectively, while fat-free mass had an effect of 22 and 26% in phase angle for girls and boys, respectively. Changes in phase angle seem to be more associated with the percentage fat mass in girls, cardiorespiratory fitness in boys, and fat-free mass in both when controlled by peak height velocity.

BackgroundIt is crucial to know the demands on basketball referees, in different match periods (MPs) and phases of competition, for planning referee training and subsequent successful refereeing.ObjectiveTo measure and evaluate the distance covered by referees in a match by measuring the number of interruptions, percentage of heart rate (%HR), and blood lactate concentration ([lac]) in different phases of competition and in different MPs.MethodWe studied the qualifying (QP), semifinal (SP), and final (FP) phases of a total of 12 matches (four matches in each phase) of the 2009–2010 Brazilian Basketball League. Distance covered, number of match interruptions, and referees’ %HR and [lac] were analyzed. We compared the results between competition phases and between MPs (1st MP, 2nd MP, 3rd MP, and 4th MP).ResultsRegarding the distances covered, we observed significant differences (P < 0.05) in the 1st, 2nd, and 3rd MPs between the FP and the other two phases (SP and QP) throughout the match, between each phase; in the 4th MP, a significant difference was found when comparing the QP and the other two phases. Comparing the periods within each phase, we found that a greater distance was covered in the 4th MP in relation to the 3rd MP during the FP. No significant differences were found among the remaining variables.ConclusionThe distances covered by referees in a basketball match increase throughout competition phases. This information is essential for planning of training and for the subsequent success of a referee.

AimsTo establish normative data for phalangeal quantitative ultrasound (QUS) measures in Brazilian students.MethodsThe sample was composed of 6870 students (3688 females and 3182 males), aged 6 to 17 years. The bone status parameter, Amplitude Dependent Speed of Sound (AD-SoS) was assessed by QUS of the phalanges using DBM Sonic BP (IGEA, Carpi, Italy) equipment. Skin color was obtained by self-evaluation. The LMS method was used to derive smoothed percentiles reference charts for AD-SoS according to sex, age, height and weight and to generate the L, M, and S parameters.ResultsGirls showed higher AD-SoS values than boys in the age groups 7–16 (p<0.001). There were no differences on AD-SoS Z-scores according to skin color. In both sexes, the obese group showed lower values of AD-SoS Z-scores compared with subjects classified as thin or normal weight. Age (r2 = 0.48) and height (r2 = 0.35) were independent predictors of AD-SoS in females and males, respectively.ConclusionAD-SoS values in Brazilian children and adolescents were influenced by sex, age and weight status, but not by skin color. Our normative data could be used for monitoring AD-SoS in children or adolescents aged 6–17 years.

BackgroundApplied research using the phase angle (PhA) in children and adolescents has increased notably. Using multilevel modeling in a fully Bayesian framework, we examined the relationships between PhA, age, sex, biological maturity status, and body size in 10–16-year-old adolescents.MethodsThe sample comprised 519 adolescents (women, n = 241; men, n = 278) from Campinas, São Paulo, Brazil. Biological maturity status was assessed with self-examination of pubertal development for sexual maturity and maturity offset protocol to estimate age at peak height velocity (PHV) for somatic maturity status. Stature and body mass were measured by anthropometry. Phase angle was calculated based on raw resistance and reactance values (50 kHz frequency) obtained by bioelectrical impedance with the foot-to-hand technology.ResultsThe multilevel regression analysis revealed that boys had significantly higher values of phase angle than girls, adjusting for age group and sexual maturity status. Overall, older and more mature adolescents had higher values of phase angle. When considering aligning variation in the phase angle by distance to estimated PHV (maturity offset), there was a higher association between the phase angle and time before and after predicted age at PHV for boys (r = 0.31, 90% CI: 0.23 to 0.39) than girls (r = 0.2, 90% CI: 0.11 to 0.28). When including body mass in the multilevel models, corresponding changes in the overall body mass mediate most of the influence of the maturity status and age group on the phase angle.ConclusionThe present study demonstrated that the variability in phase angle is related to inter-individual variation in sex, age, and maturity status, as well as differences in body size. Research with adolescents considering phase angle should use multilevel modeling with standardized parameters as default to adjust for the concurrent influence of sex, age, maturity status, and body size.

Objective: To identify the prevalence of physical inactivity in adolescent students in the city of Porto Velho, RO, Northern Brazil, and its associated factors.Methods: School-based study, conducted with 2,694 adolescents. The self-reported variable for outcome was physical inactivity. Factors associated with inactive behavior were verified by multiple logistic regression. The independent variables were inserted into the model in hierarchical blocks.Results: The overall prevalence of inactive behavior was 39.5%. Females showed a higher prevalence of physical inactivity (46.2%) than males (31.4%). Adolescents in private schools and with reports of negative health perception had a high prevalence of physical inactivity. Regarding associated factors, the female sex showed a magnitude of association of 1.84 with physical inactivity. Being in a private school was associated with a 2.54 times greater chance of physical inactivity compared to public school students. Going to school by bus, car or motorcycle was associated with a 1.29 and 1.63 higher chance of physical inactivity respectively. Adolescents who reported having a negative health perception had 1.29 higher chance of physical inactivity, while having excess body fat showed magnitude of association of 1.36 in adolescents.Conclusions: There was a high prevalence of physical inactivity in the studied adolescents. Considering that the behavior of physical inactivity adopted during adolescence may continue in adulthood, the promotion of actions that can change this behavior may improve health in the future as well as quality of life.

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La aptitud física es uno de los marcadores de salud importantes como predictor de morbilidad y mortalidad de enfermedades cardiovasculares. Objetivos: Evaluar la relación entre masa grasa con indicadores antropométricos y comparar el desempeño de la aptitud física entre niños y adolescentes categorizados con adecuado y exceso de masa grasa. Sujetos y Método: estudio transversal descriptivo en 863 escolares entre 6 a 17,9 años. Se midió el peso, estatura, circunferencia de cintura. Se evaluó la aptitud física (velocidad, agilidad y salto horizontal). Se calculó la masa grasa por ecuación antropométrica, se calculó el índice de masa corporal, índice ponderal, e índice cintura estatura. Se agruparon los datos por edad en 6 grupos. Resultados: Los niños de ambos sexos categorizados con adecuados niveles de masa grasa presentaron valores inferiores de índice de masa corporal, índice ponderal e índice cintura estatura en relación a los niños con elevados niveles de masa grasa. En la aptitud física, los niños con masa grasa adecuada fueron mejores que sus contrapartes con masa grasa elevada. En las niñas con masa grasa adecuada, se observó mejores resultados en el salto horizonty agilidad durante la adolescencia. No hubo diferencias en la prueba de velocidad. Conclusión: La masa grasa puede ser considerada como una herramienta valiosa para determinar el exceso de grasa corporal y categorizar a niños y adolescentes con adecuado y exceso de masa grasa. Además, presentar niveles aceptables de masa grasa puede contribuir a una mejor forma física en los niños en el salto horizontal, agilidad y velocidad y en las niñas únicamente en el salto horizontal y agilidad